JikesRVM

Page edited by Robin Garner OverviewThe MMTk harness is a debugging tool. It allows you to run MMTk with a simple client - a simple Java-like scripting language - which ... [More] can explicitly allocate objects, create and delete references, etc. This allows MMTk to be run and debugged stand-alone, without the entire VM, greatly simplifying initial debugging and reducing the edit-debug turnaround time. This is all accessible through the command line or an IDE such as eclipse.Running the test harnessThe harness can be run standalone or via Eclipse (or other IDE).Standalone ant mmtk-harness java -jar target/mmtk/mmtk-harness.jar <script-file> [options...] There is a collection of sample scripts in the MMTk/harness/test-scripts directory.  There is a simple wrapper script that runs all the available scripts against all the collectors, bin/test-mmtk [options...]  This script prints a PASS/FAIL line as it goes, and puts detailed output in results/mmtk.In Eclipse bin/buildit localhost --mmtk-eclipse Or in versions before 3.1.1 ant mmtk-harness && ant mmtk-harness-eclipse-project Refresh the project (or import it into eclipse), and then run 'Project > Clean'.Define a new run configuration with main class org.mmtk.harness.Main.Click Run (actually the down-arrow next to the the green button), choose 'Run Configurations...'  Select "Java Application" from the left-hand panel, and click the "new" icon (top left).Fill out the Main tab as below  Fill out the Arguments tab as below The harness makes extensive use of the java 'assert' keyword, so you should run the harness with '-ea' in the VM options.Click 'Apply' and then 'Run' to test the configuration.  Eclipse will prompt for a value for the 'script' variable - enter the name of one of the available test scripts, such as 'Lists', and click OK.  The scripts provided with MMTk are in the directory MMTk/harness/test-scripts.You can configure eclipse to display vmmagic values (Address/ObjectReference/etc) using their toString method through the Eclipse -> Preferences... -> Java -> Debug -> Detail Formatters menu. The simplest option is to check the box to use toString 'As the label for all variables'.Test harness optionsOptions are passed to the test harness as 'keyword=value' pairs.  The standard MMTk options that are available through JikesRVM are accepted (leave off the "-X:gc:"), as well as the following harness-specific options:OptionMeaningplanThe MMTk plan class.  Defaults to org.mmtk.plan.marksweep.MScollectorsThe number of concurrent collector threads (default: 1)initHeapInitial heap size.  It is also a good idea to use 'variableSizeHeap=false', since the heap growth manager uses elapsed time to make its decisions, and time is seriously dilated by the MMTk Harness.maxHeapMaximum heap size (default: 64 pages)traceDebugging messages from the MMTk Harness.  Useful trace options includeALLOC - trace object allocationAVBYTE - Mutations of the 'available byte' in each object headerCOLLECT - Detailed information during GCHASH - Hash code operationsMEMORY - page-level memory operations (map, unmap, zero)OBJECT - trace object mutation events REFERENCES - Reference type processingREMSET - Remembered set processingSANITY - Gives detailed information during Harness sanity checkingTRACEOBJECT - Traces every call to traceObject during GC (requires MMTk support) See the class org.mmtk.harness.lang.Trace for more details and trace options - most of the remaining options are only of interest to maintainers of the Harness itself.watchAddressSet a watchpoint on a given address or comma-separated list of addresses.  The harness will display every load and store to that address.watchObjectWatch modifications to a given object or comma-separated list of objects, identified by object ID (sequence number).gcEveryForce frequent GCs.  Options areALLOC - GC after every object allocation SAFEPOINT - GC at every GC safepointschedulerOptionally use the deterministic scheduler.  Options areJAVA (default) - Threads in the script are Java threads, scheduled by the host JVMDETERMINISTIC - Threads are scheduled deterministically, with yield points at every memory access.schedulerPolicySelect from several scheduling policies,FIXED - Threads yield every 'nth' yield pointRANDOM - Threads yield according to a pseudo-random policyNEVER - Threads only yield at mandatory yieldpointsyieldIntervalFor the FIXED scheduling policy, the yield frequency.randomPolicyLength randomPolicySeed randomPolicyMin randomPolicyMaxParameters for the RANDOM scheduler policy.  Whenever a thread is created, the scheduler fixes a yield pattern of 'length' integers between 'min' and 'max'.  These numbers are used as yield intervals in a circular manner.policyStatsDump statistics for the deterministic scheduler's yield policy.bits=32|64Select between 32 and 64-bit memory models.dumpPcodeDump the pseudo-code generated by the harness interpretertimeoutAbort collection if a GC takes longer than this value (seconds).  Defaults to 30. ScriptsThe MMTk/harness/test-scripts directory contains several test scripts.ScriptPurposeDescriptionAlignmentTest allocator alignment behaviourTests alignment by creating a list of objects aligned to a mixture of 4-byte and 8-byte boundaries.CyclicGarbageTest cycle detector in Reference Counting collectorsCreates large amounts of cyclic garbage in the form of circular linked lists.FixedLiveGeneral collection testHarness version of the FixedLive GC micro-benchmark.  Creates a binary tree, then allocates short-lived objects to force garbage collections.HashCodeHash code test.Creates objects and verifies that their hashcode is unchanged after a GC.LargeObjectLarge object allocator testCreates objects with sizes ranging from 2 to 32 pages (8k to 128k bytes).ListsGenerational collector stress testCreates a set of lists of varying lengths, and then allocates to force collections.  Ensures that there are Mature->Nursery, Nursery->Mature and Stack->Nursery and Stack->Mature pointers at every GC.  Remsets get a serious workout.OutOfMemoryTests out-of-memory handling.Allocates a linked list that grows until the heap fills up.QuicksortGeneral collection testImplements a list-based quicksort. ReferenceTypesReference type testCreates Weak references, forces collections and ensures that they are correctly handled.SpawnConcurrency testCreates lots of threads which allocate objects.SpreadAllocFree-list allocator testCreates large numbers of objects with random size distributions, keeping a fraction of the objects alive.SpreadAlloc16Concurrent free-list allocator testA multithreaded version of SpreadAlloc.Scripting languageBasicsThe language has three types: integer, object and user-defined. The object type behaves essentially like a double array of pointers and integers (odd, I know, but the scripting language is basically concerned with filling up the heap with objects of a certain size and reachability).  User-defined types are like Java objects without methods, 'C' structs, Pascal record types etc.Objects and user-defined types are allocated with the 'alloc' statement: alloc(p,n,align) allocates an object with 'p' pointers, 'n' integers and the given alignment; alloc(type) allocates an object of the given type.  Variables are declared 'c' style, and are optionally initialized at declaration. User-defined types are declared as follows: type list {   int value;   list next; } and fields are accessed using java-style "dot" notation, eg   list l = alloc(list);   l.value = 0;   l.next = null; At this stage, fields can only be dereferenced to one level, eg 'l.next.next' is not valid syntax - you need to introduce a temporary variable to achieve this.Object fields are referenced using syntax like "tmp.int[5]" or "tmp.object[i*3]", ie like a struct of arrays of the appropriate types.Syntax  script ::= (method|type)... method ::= ident "(" { type ident { "," type ident}... ")" ( "{" statement... "}" | "intrinsic" "class" name "method" name "signature" "(" java-class {, java class} ")" type ::= "type" ident "{" field... "}" field ::= type ident ";" statement ::= "if" "(" expr ")" block { "elif" "(" expr ")" block } [ "else" block ] | "while "(" expr ")" block | [ [ type ] ident "=" ] "alloc" "(" expr "," expr [ "," expr ] ")" ";" | [ ident "=" ] "hash" "(" expr ")" ";" | "gc" "(" ")" | "spawn" "(" ident [ "," expr ]... ")" ";" | type ident [ "=" expr ] ";" | lvalue "=" expr ";" lvalue ::= ident "=" expr ";" | ident "." type "[" expr "]" type ::= "int" | "object" | ident expr ::= expr binop expr | unop expr | "(" expr ")" | ident | ident "." type "[" expr "]" | ident "." ident | int-const | intrinsic intrinsic ::= "alloc" ( "(" expr "," expr ["," expr] ") | type ) | "(" expr ")" | "gc " "(" ")" binop ::= "+" | "-" | "*" | "/" | "%" | "&&" | "||" | "==" | "!=" unop ::= "!" | "-" MMTk Unit TestsThere is a small set of unit tests available for MMTk, using the harness as scaffolding.  These tests can be run in the standard test infrastructure using the 'mmtk-unit-tests' test set, or the shell script 'bin/unit-test-mmtk'.  Possibly more usefully, they can be run from Eclipse.To run the unit tests in Eclipse, build the mmtk harness project (see above), and add the directory testing/tests/mmtk/src to your build path (navigate to the directory in the package explorer pane in eclipse, right-click>build-path>Use as Source Folder).  Either open one of the test classes, or highlight it in the package explorer and press the 'run' button. 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Page edited by Erik Brangs - "add link for releases page" The following are the steps required to make a release of the Jikes RVM.Leading up to a release, here ... [More] are the steps to take.  All commits are to tip (default branch).Update the release number in build.xml (will continue to have +hg suffix) and commit changeExport the userguide from confluence.  Update html and pdf versions of userguide and commit.Update JIRA version management to indicate that version has been released.Generate text release notes from JIRA and put them in NEWS.txt.  Commit.Generate javadoc (apidoc target).  If needed, fix errors and commit changes.Upload javadoc to static webspace on sourceforge (htdocs/apidocs/version).  Switch "latest" symlink to point to version.In a clean hg repository (no incoming/outgoing changesets). Perform the following stepsSwitch to the release branch (hg update release)Merge tip to the release branch (hg merge default; hg commit)Edit build.xml to remove the +hg from the release number and set the hg.version field.  CommitTag the release (hg tag <version>; hg push)Clone a new .hg repository and create the release tar ballshg clone http://hg.code.sourceforge.net/p/jikesrvm/code -b release jikesrvm-versionrm -rf jikesrvm/.hgtar cjf jikesrvm-version.tar.bz2 jikesrvm-version;  tar czf jikesrvm-version.tar.gz jikesrvm-version;Extract the portion of NEWS.txt relevant to this release into README.txt (will be used for ReleaseNotes on SF file download).Publish and announce the releaseUpload release tar balls and README.txt to sourceforge; set it as default download using Files GUI.Update the confluence Releases page to link to the new download versionSend out mail announcements to jikesrvm-announce and jikesrvm-researchersAlso post announcement in SF news and Confluence news. View Online · View Changes Online [Less]

Page edited by Erik Brangs - "update to 3.1.3" Releases of Jikes RVM are available from the Sourceforge download page.The most recent release of Jikes RVM is ... [More] 3.1.3. View Online · View Changes Online [Less]

Page edited by Erik Brangs - "update page to reflect that JIRA signup is currently impossible" Thank you for coming to this page. We are sorry if you are ... [More] experiencing difficulties with the Jikes RVM. While we do our best to test and debug Jikes RVM, with so much variety of hardware and configurations it may be that we've missed something. This is where you can make a contribution to Jikes RVM by just telling us what isn't working.Reporting bugs is important to us! When we know something isn't working we can look into fixing it and schedule the fix in our release road map. This is also true if you are experiencing problems with a Jikes RVM that you have modified for your own development; knowing how people modify Jikes RVM will help us to make it more flexible and robust in the future.How to report bugsThe Jikes RVM Bug Tracker is managed using a system called JIRA, which is really friendly to use. To avoid spam, JIRA does require a user account when reporting or commenting on issues. But signing up is easy.Important update: Signup for JIRA is currently broken but Codehaus is working on fixing the issue. In the meantime, you can either signup using Xircles, which provides both a Wiki and a JIRA account, orreport your bug on the researchers mailing listCheck that your issue has not been reported yetFirst, please take some time to search or browse the list of issues to see if your problem has been reported before. If it has, you can let us know that this issue is important to you by voting to have it fixed. Moreover, you can also select to watch the issue; this way, JIRA will notify you of any updates to it.Even if your issue has been reported yet, you may be able to provide us with some further information about the circumstances causing the problem. If this is the case, please comment on the existing issue.Create a bug reportOnce you have checked that your issue has not been reported before, create a new issue by following the instructions in JIRA and completing the following checklist:Give a clear but succinct summary, as this is the title JIRA will assign to your issue.If possible, state which components of Jikes RVM exhibit the problem, e.g., if you problem is specific to one particular garbage collector or compiler.Clearly identify the environment the problem occurs in:The version of Jikes RVM which exhibits the problem (If you select the hg tip as a version, please also copy & paste the output of hg identify into the Environment field.)The build/target host (ia32-linux, x86_64-osx, etc.) and configuration (production, prototype-opt, etc.) you have used when building the RVMThe operating system/distribution and kernel version (Copy & paste the output of uname -a into the Environment field.)Describe both the problem and the circumstances under which the problem occurs.Please provide enough information that we can reproduce the error. At the very least, give the exact command line used to run the RVM. If you are running a workload which does not stem from a well-known benchmarks suite (the DaCapo benchmarks, SPECjvm, etc.), please provide us with a download URI for your workload, so that we can run it ourselves.Also, please note that the code of Jikes RVM uses assertions extensively. If your problem shows up in one of the production configurations, for testing purposes configure the RVM such that assertions are enabled (development rather than production). Often, a failed assertion provides a good indication of what went wrong, so please include the stack trace from the failed assertion in your bug report.NB. This page is the landing pad for when an abnormal condition has terminated Jikes RVM. View Online · View Changes Online [Less]

Page edited by Erik Brangs - "updated page to reflect that we won't take part in GSoC 2013" As in previous years, Jikes RVM has applied to Google Summer of ... [More] Code. We were not accepted as mentoring organization for GSoC in 2013.Hints for studentsYou can still take part in GSoC and work for another mentoring organization. Students interested in GSoC should read at least the GSoC FAQ and Google's advice for students. There's also a lot of helpful information about GSoC that's provided by mentoring organizations and previous GSoC students (use your favorite search engine to find it).We will likely apply for GSoC again next year.Archived stuff that's no longer relevant for GSoC 2013Hints for students specific to Jikes RVMIf the Jikes RVM project sounds like it could be a good fit for you, you can already start to get familiar with Jikes RVM. Checkout the source code and read the user guide. Build the Jikes RVM, run some tests and take a look at the codebase. You should have your development environment already set up before applying. Don't hesitate to ask on the mailing lists if you need help.If/when we've been accepted as a mentoring organization, students can take a look at our guidelines on making an application. We expect that students get familiar with the Jikes RVM and the Jikes RVM community before applying.What's in it for me?All mentors get a smart Google t-shirt. The project gets some new contributors, and the students get substantial amounts of cash and experience in open source development. The Jikes RVM project has seen substantial benefits from GSoC in previous years, including a new native threading model and additions to the core team of developers.Adding new project suggestionsPlease add your ideas to the wiki below, ideally using the template shown below. You can also contribute an idea if you don't have a wiki account: just describe it on the researchers mailing list. Project TitlefooRVM area{compiler, classlib, MMTk, infrastructure...}outlineparagraph description of project ideareferenceslinks to related projects, academic papers, etcneeded skillsskills that the student should have and/or needs to acquire during the projectdifficultya difficulty estimate for the project, e.g. easy, medium, difficultinterested mentoryour name and a contact link or "TBD" if you can't mentorProject suggestions (aka ideas list) Project TitleImplement the Java Management extensions (JMX) APIRVM areaclasslib, MMTk, threading, compileroutlineThe Java Management Extensions provide a way to monitor and manage Java Virtual machines. The Jikes RVM can collect significantly more profiling data and runtime statistics than an average JVM as a result of it being focussed on research activities. These statistics would ideally be exported using JMX and could potentially provide a standard mechanism for monitoring the performance and health of the virtual machine and its components.As a first step, students should focus on laying groundwork for a suitable implementation of the API:Update the JMX code from GSoC 2007 (written by Andrew John Hughes) to work with the current Jikes RVMImplement all the parts of the API that are requiredWrite automated tests that can be integrated into our test frameworksAfter that has happened, students should implement the optional parts of the API and Jikes RVM-specific features. The exact set of features will need to be discussed with the community at the appropriate time.referencesBlog post about JMX with links to further documentationOur bugtracker entry for JMXWeb view of the JMX branch in the historic svn repository (use "svn checkout svn://svn.code.sf.net/p/jikesrvm/svn/rvmroot/branches/RVM-127-JMX" to checkout the code)needed skillsJavadifficultyeasyinterested mentorTony Hosking, Steve Blackburn  Project TitleImplement the JVM Tool Interface (JVMTI)RVM areathreading, JNIoutlineThe JVM Tool interface is part of the Java Platform Debugger Architecture that JVMs can implement to provide debugging capabilities. We would like to have a full JMVTI implementation to allow debugging of Java applications that are running on Jikes RVM. Another benefit of JVMTI is that it allows low-level access to JVM internals. This can be used for instrumenting and monitoring the Jikes RVM using low-level code.There is already a partial JMVTI implementation that was written by James Bornholt for GSoC 2011. His implementation should be used as a basis for this project.referencesWriteup of James Bornholt on the GSoC 2011 pageWeb view of previous GSoC 2011 JVMTI workneeded skillsC, C++, Java, willingness to deal with low-level detailsdifficultymediuminterested mentorEliot Moss  Project TitleImprove (or rethink) CatTrackRVM areainfrastructureoutlineThe Jikes RVM project currently uses the Ruby-on-Rails application CatTrack to track test results. CatTrack is also responsible for sending regression mails.This project would consist of upgrading CatTrack to use a more recent version of Ruby-on-Rails instead of the ancient Ruby-on-Rails 1.2.6. Potential candidates must have experience in Ruby-on-Rails to be able to take on this project: we don't have the necessary expertise to provide adequate mentoring to RoR beginners. The exact version numbers and the upgrade process need to be coordinated with our contacts at the Australian National University (where the servers are located). New features can be added to CatTrack after the upgrade is complete.An alternative approach would be to get rid of CatTrack completely and move to a more general open-source solution. Note that this would be a much more disruptive change. A student proposal that suggests this approach must be very convincing to be considered. Another constraint for proposals of this kind is that we want to avoid using yet another language in our build infrastructure (see RVM-85 ). It might be acceptable to replace Ruby with another language but this must be discussed before such a proposal is submitted.The X10 language project also uses CatTrack for their regression mails. Candidates should be prepared to coordinate with somebody from the X10 team to ensure that an upgraded version of CatTrack (or a replacement) is also a viable solution for them.referencesWeb view of the CatTrack repositoryneeded skillsprior Ruby-on-Rails experience, XML, basic knowledge about databasesdifficultydifficultinterested mentorSteve Blackburn  Project TitleImprove testing situation for JIkes RVMRVM areainfrastructure, (additional subsystems as chosen by the student)outlineAn infrastructure for unit tests and some initial unit tests were added to the Jikes RVM in GSoC 2012 by João Reys Santos. However, there is still a lot of work to do before we can consider the codebase to be reasonably well tested. We need more unit tests as well as more black-box tests.Students should pick an area of interest (e.g. compilers, JNI, MMTk, classloading, threading, ...) and/or motivating use cases (e.g. get benchmark X or application Y running on Jikes RVM), identify and fix the corresponding problems and introduce adequate (unit) tests.Note that extra effort will be required if students want to use mocking. Mockito does not work with GNU Classpath-based JVMs and our OpenJDK-port is not yet ready.referencesbook: Michael Feathers, Working effectively with legacy code, Pearson Education, 2004book: Andreas Zeller, Why programs fail: A guide to systematic debugging, Morgan Kaufmann, 2009needed skillsJava, Ant, debugging without a debuggerdifficultyeasy to difficult (depends on the chosen tasks and areas)interested mentorTony Hosking  Project TitleBytecode verifierRVM areaclassloading, compilersoutlineJikes RVM currently does not implement a bytecode verifier. We would like to have a bytecode verifier that can verify classfiles at least up until Java 6 (we don't support Java 7 yet). The verifier needs to work with the baseline compiler as well as the optimizing compiler. Ideally, it should be possible to use the verifier from the command line without actually running the bytecode that is supposed to be checked. This could be done in a similar way to the OptTestHarness which enables users to control the compilers.The verifier should be designed to support custom verification constraints. Some examples for possible constraints are listed in the JIRA issue linked below.referencesJIRA issue for the bytecode verifierJasmin assembler (useful for creating test cases that trigger verifier errors)Chapter 4 of the JVM Specificationneeded skillsJava, reading papers and specifications, implementing algorithms from specifications and papersdifficultymediuminterested mentorEliot Moss  Project TitleGCspyRVM areaMMTkoutlineThe GCspy framework for garbage collector visualization has become out-of-date and needs improving [RVM-388]. GCSpy 2.0 should update the framework to work properly with the latest version of Jikes RVM. In particular, it should support discontiguous spaces and provide drivers for more of MMTk's GC algorithms. In addition, the rewrite might improve modularity, and possibly integrate with the Eclipse Rich Client Platform.referencesGCspy: an adaptable heap visualisation frameworkneeded skillsJava, C++, willingness to deal with low-level details, some understanding of garbage collectiondifficultyfairly straightforwardinterested mentorRichard Jones  Project TitleImplement the Compressor garbage collectorRVM areaMMTkoutlineA Stop-The-World variant of the Compressor garbage collector was implemented for Jikes RVM in  GSoC 2010 by Michael Gendelman. The goal of this project is to improve the stability of Michael Gendelman's implementation so that it can be merged to mainline. Performance tuning may also be needed.Students that are interested in this project should be familiar with garbage collection and MMTk.Hint for very ambitious students: You can work on more complex variants of the Compressor (e.g. a concurrent version) once the the Stop-The-World variant has been merged and the project has determined that its quality is suitable.referencespaper: Haim Kermanya and Erez Petrank, The Compressor: concurrent, incremental, and parallel compaction (ACM link)JIRA issue for the compressor (includes a link to the paper)Michael Gendelman's work on the Compressor (includes a design document on the wiki)needed skillsJava, willingness to deal with low-level details, familiarity with garbage collectiondifficultydifficultinterested mentorRichard Jones or Steve Blackburn  Project TitlePort Jikes RVM compilers to ARMRVM areacompilersoutlineJikes RVM currently supports 32-bit Intel, and 32- and 64-bit Power PC architectures. This project involves porting Jikes RVM (initially the baseline compiler) to the 32-bit ARM architecture. Ambitious students could consider the optimizing compiler too, as a second step. Lots of preparatory work has been done in this area. I had an undergraduate student project at Glasgow University this year. He has done excellent refactoring work and we should be able to build on this to get a fully functional baseline compiler.referencesWhen my student's project is marked, I will put a PDF document up here. In the mean time, here is an out of date thesis about an earlier porting effort to ARM.needed skillsJava, willingness to deal with low-level details, familiarity with ARM instruction setdifficultymoderate to difficultinterested mentorJeremy Singer, also support available from colleagues at ARM directly. Please get in touch to discuss details!  Project TitleImplement new Quick compilerRVM areacompilersoutlineA Quick Compiler that does simple optimization and some use of registers, possibly modeled after existing dynamic code generation systems such as that of QEMU or valgrind. The point of such a compiler is to exploit "low hanging fruit". Previous work (10 years ago) took a somewhat different approach, but suggested that a compiler that applied a simple approach to register allocation and some simple optimizations reduced total execution over the current Baseline or Baseline+Opt compilation systems.referencesQEMU and valgrind are good starting points for developing the compilation / optimization strategy.needed skillscompiler expertise (analyses and optimizations)difficultymoderate to difficultinterested mentorEliot Moss  Project TitleReengineer Command Line Flag parsing in Jikes RVMRVM areainfrastructureoutlineJikes RVM has lots of command-line flags, as you can see from the command line help. Researchers add new flags all the time, when they are working on experimental features. The current techniques for adding new flags, parsing flags, etc is quite complex. This project is about refactoring the code to make command line flag handling more straightforward. Possibilities (negotiable) include autocomplete for flags, suggestions for unrecognised flags, etc.referencesMaybe look at Google commandline flags library, and at bash completion for some ideas.needed skillsJavadifficultyeasy to moderateinterested mentorJeremy Singer Please get in touch to discuss details! View Online · View Changes Online [Less]

Page edited by Erik Brangs - "changed JavaDoc requirements to say that comments should not be copied" Regrettably, some code in the current system does not ... [More] follow any consistent coding style. This is an unfortunate residuum of the system's evolution.  To alleviate this problem, we present this style guide for new Java™ code; it's just a small tweak of Sun®'s style guide.  We also use checkstyle to support a gradually expanding subset of these conventions.  The current set of enforced checkstyle rules are defined by $RVM_ROOT/build/checkstyle/rvm-checks.xml and are verified as part of the pre-commit test run. To check for violations of the coding style without running the tests, use buildit or run "ant checkstyle" from the command line.File HeadersEvery file needs to have the license header.A Java example of the notices follows./* * This file is part of the Jikes RVM project (http://jikesrvm.org). * * This file is licensed to You under the Eclipse Public License (EPL); * You may not use this file except in compliance with the License. You * may obtain a copy of the License at * * http://www.opensource.org/licenses/eclipse-1.0.php * * See the COPYRIGHT.txt file distributed with this work for information * regarding copyright ownership. */package org.jikesrvm;import org.jikesrvm.classloader.ClassLoader; // FILL ME IN/** * TODO Substitute a brief description of what this program or library does. */Coding style descriptionThe Jikes™ RVM coding style guidelines are defined with reference to the Sun® Microsystems "Code Conventions for the Java™ Programming Language", with a few exceptions listed below. Most of the style guide is intuitive; however, please read through the document (or at least look at its sample code).We have adopted four modifications to the Sun code conventions:Two-space indenting The Sun coding convention suggests 4 space indenting; however with 80-column lines and four-space indenting, there is very little room left for code. Thus, we recommend using 2 space indenting. There are to be no tabs in the source files or trailing white space on any line.132 column lines in exceptional cases The Sun coding convention is that lines be no longer than 80 columns. Several Jikes RVM contributors have found this constraining. Therefore, we allow 132 column lines for exceptional cases, such as to avoid bad line breaks.if (VM.VerifyAssertions) As a special case, the condition if (VM.VerifyAssertions) is usually immediately followed by the call to VM._assert(), with a single space substituting for the normal newline-and-indentation. There's an example elsewhere in this document.Capitalized fields Under the Sun coding conventions, and as specified in The Java Language Specification, Second Edition, the names of fields begin with a lowercase letter. (The only exception they give is for some final static constants, which have names ALL_IN_CAPITAL_LETTERS, with underscores separating them.) That convention reserves IdentifiersBeginningWithACapitalLetterFollowedByMixedCase for the names of classes and interfaces. However, most of the final fields in the Configuration class and the Properties interface also are in that format. Since the VM class inherits fields from both Properties and Configuration, that's how we get VM.VerifyAssertions, etc.Javadoc requirementsAll files should contain descriptive comments in Javadoc™ form so that documentation can be generated automatically. Of course, additional non-Javadoc source code comments should appear as appropriate.All classes and methods should have a block comment describing them. JavaDoc comments must not be copied from methods that are being overriden. If the comment from the method that you are overriding is sufficient, you do not need to provide JavaDoc for the newly added method - JavaDoc will automatically copy the JavaDoc from the overriden method. If you want to extend the comment from the overriden method with new information, use {@inheritDoc} to copythe comment from the superclass and add your text.All methods contain a short description of their arguments (using @param), the return value (using @return) and the exceptions they may throw (using @throws).Each class should include @see and @link references as appropriate. View Online · View Changes Online [Less]

Page edited by Erik Brangs - "fix typo" As in previous years, Jikes RVM will apply to Google Summer of Code for funding for student projects.The GSoC 2013 ... [More] timeline has been published. The next date of importance is: Announcement of accepted mentoring organizations on April 8 2013 - 19:00 UTCOur current task is to collate a set of interesting project proposals and encourage students to apply for GSoC. We can re-use ideas from previous proposals, or come up with totally new ideas.Hints for studentsThe accepted mentoring organizations haven't been announced yet. However, it's not too early to read the Google Summer of Code documentation. Students should read at least the GSoC FAQ and Google's advice for students. There's also a lot of helpful information about GSoC that's provided by mentoring organizations and previous GSoC students (use your favorite search engine to find it).If the Jikes RVM project sounds like it could be a good fit for you, you can already start to get familiar with Jikes RVM. Checkout the source code and read the user guide. Build the Jikes RVM, run some tests and take a look at the codebase. You should have your development environment already set up before applying. Don't hesitate to ask on the mailing lists if you need help.If/when we've been accepted as a mentoring organization, students can take a look at our guidelines on making an application. We expect that students get familiar with the Jikes RVM and the Jikes RVM community before applying.What's in it for me?All mentors get a smart Google t-shirt. The project gets some new contributors, and the students get substantial amounts of cash and experience in open source development. The Jikes RVM project has seen substantial benefits from GSoC in previous years, including a new native threading model and additions to the core team of developers.Adding new project suggestionsPlease add your ideas to the wiki below, ideally using the template shown below. You can also contribute an idea if you don't have a wiki account: just describe it on the researchers mailing list. Project TitlefooRVM area{compiler, classlib, MMTk, infrastructure...}outlineparagraph description of project ideareferenceslinks to related projects, academic papers, etcneeded skillsskills that the student should have and/or needs to acquire during the projectdifficultya difficulty estimate for the project, e.g. easy, medium, difficultinterested mentoryour name and a contact link or "TBD" if you can't mentorProject suggestions (aka ideas list) Project TitleImplement the Java Management extensions (JMX) APIRVM areaclasslib, MMTk, threading, compileroutlineThe Java Management Extensions provide a way to monitor and manage Java Virtual machines. The Jikes RVM can collect significantly more profiling data and runtime statistics than an average JVM as a result of it being focussed on research activities. These statistics would ideally be exported using JMX and could potentially provide a standard mechanism for monitoring the performance and health of the virtual machine and its components.As a first step, students should focus on laying groundwork for a suitable implementation of the API:Update the JMX code from GSoC 2007 (written by Andrew John Hughes) to work with the current Jikes RVMImplement all the parts of the API that are requiredWrite automated tests that can be integrated into our test frameworksAfter that has happened, students should implement the optional parts of the API and Jikes RVM-specific features. The exact set of features will need to be discussed with the community at the appropriate time.referencesBlog post about JMX with links to further documentationOur bugtracker entry for JMXWeb view of the JMX branch in the historic svn repository (use "svn checkout svn://svn.code.sf.net/p/jikesrvm/svn/rvmroot/branches/RVM-127-JMX" to checkout the code)needed skillsJavadifficultyeasyinterested mentorTony Hosking, Steve Blackburn  Project TitleImplement the JVM Tool Interface (JVMTI)RVM areathreading, JNIoutlineThe JVM Tool interface is part of the Java Platform Debugger Architecture that JVMs can implement to provide debugging capabilities. We would like to have a full JMVTI implementation to allow debugging of Java applications that are running on Jikes RVM. Another benefit of JVMTI is that it allows low-level access to JVM internals. This can be used for instrumenting and monitoring the Jikes RVM using low-level code.There is already a partial JMVTI implementation that was written by James Bornholt for GSoC 2011. His implementation should be used as a basis for this project.referencesWriteup of James Bornholt on the GSoC 2011 pageWeb view of previous GSoC 2011 JVMTI workneeded skillsC, C++, Java, willingness to deal with low-level detailsdifficultymediuminterested mentorEliot Moss  Project TitleImprove (or rethink) CatTrackRVM areainfrastructureoutlineThe Jikes RVM project currently uses the Ruby-on-Rails application CatTrack to track test results. CatTrack is also responsible for sending regression mails.This project would consist of upgrading CatTrack to use a more recent version of Ruby-on-Rails instead of the ancient Ruby-on-Rails 1.2.6. Potential candidates must have experience in Ruby-on-Rails to be able to take on this project: we don't have the necessary expertise to provide adequate mentoring to RoR beginners. The exact version numbers and the upgrade process need to be coordinated with our contacts at the Australian National University (where the servers are located). New features can be added to CatTrack after the upgrade is complete.An alternative approach would be to get rid of CatTrack completely and move to a more general open-source solution. Note that this would be a much more disruptive change. A student proposal that suggests this approach must be very convincing to be considered. Another constraint for proposals of this kind is that we want to avoid using yet another language in our build infrastructure (see RVM-85 ). It might be acceptable to replace Ruby with another language but this must be discussed before such a proposal is submitted.The X10 language project also uses CatTrack for their regression mails. Candidates should be prepared to coordinate with somebody from the X10 team to ensure that an upgraded version of CatTrack (or a replacement) is also a viable solution for them.referencesWeb view of the CatTrack repositoryneeded skillsprior Ruby-on-Rails experience, XML, basic knowledge about databasesdifficultydifficultinterested mentorSteve Blackburn  Project TitleImprove testing situation for JIkes RVMRVM areainfrastructure, (additional subsystems as chosen by the student)outlineAn infrastructure for unit tests and some initial unit tests were added to the Jikes RVM in GSoC 2012 by João Reys Santos. However, there is still a lot of work to do before we can consider the codebase to be reasonably well tested. We need more unit tests as well as more black-box tests.Students should pick an area of interest (e.g. compilers, JNI, MMTk, classloading, threading, ...) and/or motivating use cases (e.g. get benchmark X or application Y running on Jikes RVM), identify and fix the corresponding problems and introduce adequate (unit) tests.Note that extra effort will be required if students want to use mocking. Mockito does not work with GNU Classpath-based JVMs and our OpenJDK-port is not yet ready.referencesbook: Michael Feathers, Working effectively with legacy code, Pearson Education, 2004book: Andreas Zeller, Why programs fail: A guide to systematic debugging, Morgan Kaufmann, 2009needed skillsJava, Ant, debugging without a debuggerdifficultyeasy to difficult (depends on the chosen tasks and areas)interested mentorTony Hosking  Project TitleBytecode verifierRVM areaclassloading, compilersoutlineJikes RVM currently does not implement a bytecode verifier. We would like to have a bytecode verifier that can verify classfiles at least up until Java 6 (we don't support Java 7 yet). The verifier needs to work with the baseline compiler as well as the optimizing compiler. Ideally, it should be possible to use the verifier from the command line without actually running the bytecode that is supposed to be checked. This could be done in a similar way to the OptTestHarness which enables users to control the compilers.The verifier should be designed to support custom verification constraints. Some examples for possible constraints are listed in the JIRA issue linked below.referencesJIRA issue for the bytecode verifierJasmin assembler (useful for creating test cases that trigger verifier errors)Chapter 4 of the JVM Specificationneeded skillsJava, reading papers and specifications, implementing algorithms from specifications and papersdifficultymediuminterested mentorEliot Moss  Project TitleGCspyRVM areaMMTkoutlineThe GCspy framework for garbage collector visualization has become out-of-date and needs improving [RVM-388]. GCSpy 2.0 should update the framework to work properly with the latest version of Jikes RVM. In particular, it should support discontiguous spaces and provide drivers for more of MMTk's GC algorithms. In addition, the rewrite might improve modularity, and possibly integrate with the Eclipse Rich Client Platform.referencesGCspy: an adaptable heap visualisation frameworkneeded skillsJava, C++, willingness to deal with low-level details, some understanding of garbage collectiondifficultyfairly straightforwardinterested mentorRichard Jones  Project TitleImplement the Compressor garbage collectorRVM areaMMTkoutlineA Stop-The-World variant of the Compressor garbage collector was implemented for Jikes RVM in  GSoC 2010 by Michael Gendelman. The goal of this project is to improve the stability of Michael Gendelman's implementation so that it can be merged to mainline. Performance tuning may also be needed.Students that are interested in this project should be familiar with garbage collection and MMTk.Hint for very ambitious students: You can work on more complex variants of the Compressor (e.g. a concurrent version) once the the Stop-The-World variant has been merged and the project has determined that its quality is suitable.referencespaper: Haim Kermanya and Erez Petrank, The Compressor: concurrent, incremental, and parallel compaction (ACM link)JIRA issue for the compressor (includes a link to the paper)Michael Gendelman's work on the Compressor (includes a design document on the wiki)needed skillsJava, willingness to deal with low-level details, familiarity with garbage collectiondifficultydifficultinterested mentorRichard Jones or Steve Blackburn  Project TitlePort Jikes RVM compilers to ARMRVM areacompilersoutlineJikes RVM currently supports 32-bit Intel, and 32- and 64-bit Power PC architectures. This project involves porting Jikes RVM (initially the baseline compiler) to the 32-bit ARM architecture. Ambitious students could consider the optimizing compiler too, as a second step. Lots of preparatory work has been done in this area. I had an undergraduate student project at Glasgow University this year. He has done excellent refactoring work and we should be able to build on this to get a fully functional baseline compiler.referencesWhen my student's project is marked, I will put a PDF document up here. In the mean time, here is an out of date thesis about an earlier porting effort to ARM.needed skillsJava, willingness to deal with low-level details, familiarity with ARM instruction setdifficultymoderate to difficultinterested mentorJeremy Singer, also support available from colleagues at ARM directly. Please get in touch to discuss details!  Project TitleImplement new Quick compilerRVM areacompilersoutlineA Quick Compiler that does simple optimization and some use of registers, possibly modeled after existing dynamic code generation systems such as that of QEMU or valgrind. The point of such a compiler is to exploit "low hanging fruit". Previous work (10 years ago) took a somewhat different approach, but suggested that a compiler that applied a simple approach to register allocation and some simple optimizations reduced total execution over the current Baseline or Baseline+Opt compilation systems.referencesQEMU and valgrind are good starting points for developing the compilation / optimization strategy.needed skillscompiler expertise (analyses and optimizations)difficultymoderate to difficultinterested mentorEliot Moss  Project TitleReengineer Command Line Flag parsing in Jikes RVMRVM areainfrastructureoutlineJikes RVM has lots of command-line flags, as you can see from the command line help. Researchers add new flags all the time, when they are working on experimental features. The current techniques for adding new flags, parsing flags, etc is quite complex. This project is about refactoring the code to make command line flag handling more straightforward. Possibilities (negotiable) include autocomplete for flags, suggestions for unrecognised flags, etc.referencesMaybe look at Google commandline flags library, and at bash completion for some ideas.needed skillsJavadifficultyeasy to moderateinterested mentorJeremy Singer Please get in touch to discuss details! View Online · View Changes Online [Less]

Page edited by Erik Brangs - "removed superfluous word" As in previous years, Jikes RVM will apply to Google Summer of Code for funding for student ... [More] projects.The GSoC 2013 timeline has been published. The first date of importance is: Organization application deadline on March 29 2013Our current task is to collate a set of interesting project proposals and encourage students to apply for GSoC. We can re-use ideas from previous proposals, or come up with totally new ideas.Hints for studentsThe application for mentoring organizations hasn't been opened yet. However, it's not too early to read the Google Summer of Code documentation. Students should read at least the GSoC FAQ and Google's advice for students. There's also a lot of helpful information about GSoC that's provided by mentoring organizations and previous GSoC students (use your favorite search engine to find it).If the Jikes RVM project sounds like it could be a good fit for you, you can already start to get familiar with Jikes RVM. Checkout the source code and read the user guide. Build the Jikes RVM, run some tests and take a look at the codebase. You should have your development environment already set up before applying. Don't hesitate to ask on the mailing lists if you need help.If/when we've been accepted as a mentoring organization, students can take a look at our guidelines on making an application. We expect that students get familiar with the Jikes RVM and the Jikes RVM community before applying.What's in it for me?All mentors get a smart Google t-shirt. The project gets some new contributors, and the students get substantial amounts of cash and experience in open source development. The Jikes RVM project has seen substantial benefits from GSoC in previous years, including a new native threading model and additions to the core team of developers.Adding new project suggestionsPlease add your ideas to the wiki below, ideally using the template shown below. You can also contribute an idea if you don't have a wiki account: just describe it on on the researchers mailing list. Project TitlefooRVM area{compiler, classlib, MMTk, infrastructure...}outlineparagraph description of project ideareferenceslinks to related projects, academic papers, etcneeded skillsskills that the student should have and/or needs to acquire during the projectdifficultya difficulty estimate for the project, e.g. easy, medium, difficultinterested mentoryour name and a contact link or "TBD" if you can't mentorProject suggestions (aka ideas list) Project TitleImplement the Java Management extensions (JMX) APIRVM areaclasslib, MMTk, threading, compileroutlineThe Java Management Extensions provide a way to monitor and manage Java Virtual machines. The Jikes RVM can collect significantly more profiling data and runtime statistics than an average JVM as a result of it being focussed on research activities. These statistics would ideally be exported using JMX and could potentially provide a standard mechanism for monitoring the performance and health of the virtual machine and its components.As a first step, students should focus on laying groundwork for a suitable implementation of the API:Update the JMX code from GSoC 2007 (written by Andrew John Hughes) to work with the current Jikes RVMImplement all the parts of the API that are requiredWrite automated tests that can be integrated into our test frameworksAfter that has happened, students should implement the optional parts of the API and Jikes RVM-specific features. The exact set of features will need to be discussed with the community at the appropriate time.referencesBlog post about JMX with links to further documentationOur bugtracker entry for JMXWeb view of the JMX branch in the historic svn repository (use "svn checkout svn://svn.code.sf.net/p/jikesrvm/svn/rvmroot/branches/RVM-127-JMX" to checkout the code)needed skillsJavadifficultyeasyinterested mentorTony Hosking, Steve Blackburn  Project TitleImplement the JVM Tool Interface (JVMTI)RVM areathreading, JNIoutlineThe JVM Tool interface is part of the Java Platform Debugger Architecture that JVMs can implement to provide debugging capabilities. We would like to have a full JMVTI implementation to allow debugging of Java applications that are running on Jikes RVM. Another benefit of JVMTI is that it allows low-level access to JVM internals. This can be used for instrumenting and monitoring the Jikes RVM using low-level code.There is already a partial JMVTI implementation that was written by James Bornholt for GSoC 2011. His implementation should be used as a basis for this project.referencesWriteup of James Bornholt on the GSoC 2011 pageWeb view of previous GSoC 2011 JVMTI workneeded skillsC, C++, Java, willingness to deal with low-level detailsdifficultymediuminterested mentorEliot Moss  Project TitleImprove (or rethink) CatTrackRVM areainfrastructureoutlineThe Jikes RVM project currently uses the Ruby-on-Rails application CatTrack to track test results. CatTrack is also responsible for sending regression mails.This project would consist of upgrading CatTrack to use a more recent version of Ruby-on-Rails instead of the ancient Ruby-on-Rails 1.2.6. Potential candidates must have experience in Ruby-on-Rails to be able to take on this project: we don't have the necessary expertise to provide adequate mentoring to RoR beginners. The exact version numbers and the upgrade process need to be coordinated with our contacts at the Australian National University (where the servers are located). New features can be added to CatTrack after the upgrade is complete.An alternative approach would be to get rid of CatTrack completely and move to a more general open-source solution. Note that this would be a much more disruptive change. A student proposal that suggests this approach must be very convincing to be considered. Another constraint for proposals of this kind is that we want to avoid using yet another language in our build infrastructure (see RVM-85 ). It might be acceptable to replace Ruby with another language but this must be discussed before such a proposal is submitted.The X10 language project also uses CatTrack for their regression mails. Candidates should be prepared to coordinate with somebody from the X10 team to ensure that an upgraded version of CatTrack (or a replacement) is also a viable solution for them.referencesWeb view of the CatTrack repositoryneeded skillsprior Ruby-on-Rails experience, XML, basic knowledge about databasesdifficultydifficultinterested mentorSteve Blackburn  Project TitleImprove testing situation for JIkes RVMRVM areainfrastructure, (additional subsystems as chosen by the student)outlineAn infrastructure for unit tests and some initial unit tests were added to the Jikes RVM in GSoC 2012 by João Reys Santos. However, there is still a lot of work to do before we can consider the codebase to be reasonably well tested. We need more unit tests as well as more black-box tests.Students should pick an area of interest (e.g. compilers, JNI, MMTk, classloading, threading, ...) and/or motivating use cases (e.g. get benchmark X or application Y running on Jikes RVM), identify and fix the corresponding problems and introduce adequate (unit) tests.Note that extra effort will be required if students want to use mocking. Mockito does not work with GNU Classpath-based JVMs and our OpenJDK-port is not yet ready.referencesbook: Michael Feathers, Working effectively with legacy code, Pearson Education, 2004book: Andreas Zeller, Why programs fail: A guide to systematic debugging, Morgan Kaufmann, 2009needed skillsJava, Ant, debugging without a debuggerdifficultyeasy to difficult (depends on the chosen tasks and areas)interested mentorTony Hosking  Project TitleBytecode verifierRVM areaclassloading, compilersoutlineJikes RVM currently does not implement a bytecode verifier. We would like to have a bytecode verifier that can verify classfiles at least up until Java 6 (we don't support Java 7 yet). The verifier needs to work with the baseline compiler as well as the optimizing compiler. Ideally, it should be possible to use the verifier from the command line without actually running the bytecode that is supposed to be checked. This could be done in a similar way to the OptTestHarness which enables users to control the compilers.The verifier should be designed to support custom verification constraints. Some examples for possible constraints are listed in the JIRA issue linked below.referencesJIRA issue for the bytecode verifierJasmin assembler (useful for creating test cases that trigger verifier errors)Chapter 4 of the JVM Specificationneeded skillsJava, reading papers and specifications, implementing algorithms from specifications and papersdifficultymediuminterested mentorEliot Moss  Project TitleGCspyRVM areaMMTkoutlineThe GCspy framework for garbage collector visualization has become out-of-date and needs improving [RVM-388]. GCSpy 2.0 should update the framework to work properly with the latest version of Jikes RVM. In particular, it should support discontiguous spaces and provide drivers for more of MMTk's GC algorithms. In addition, the rewrite might improve modularity, and possibly integrate with the Eclipse Rich Client Platform.referencesGCspy: an adaptable heap visualisation frameworkneeded skillsJava, C++, willingness to deal with low-level details, some understanding of garbage collectiondifficultyfairly straightforwardinterested mentorRichard Jones  Project TitleImplement the Compressor garbage collectorRVM areaMMTkoutlineA Stop-The-World variant of the Compressor garbage collector was implemented for Jikes RVM in  GSoC 2010 by Michael Gendelman. The goal of this project is to improve the stability of Michael Gendelman's implementation so that it can be merged to mainline. Performance tuning may also be needed.Students that are interested in this project should be familiar with garbage collection and MMTk.Hint for very ambitious students: You can work on more complex variants of the Compressor (e.g. a concurrent version) once the the Stop-The-World variant has been merged and the project has determined that its quality is suitable.referencespaper: Haim Kermanya and Erez Petrank, The Compressor: concurrent, incremental, and parallel compaction (ACM link)JIRA issue for the compressor (includes a link to the paper)Michael Gendelman's work on the Compressor (includes a design document on the wiki)needed skillsJava, willingness to deal with low-level details, familiarity with garbage collectiondifficultydifficultinterested mentorRichard Jones or Steve Blackburn  Project TitlePort Jikes RVM compilers to ARMRVM areacompilersoutlineJikes RVM currently supports 32-bit Intel, and 32- and 64-bit Power PC architectures. This project involves porting Jikes RVM (initially the baseline compiler) to the 32-bit ARM architecture. Ambitious students could consider the optimizing compiler too, as a second step. Lots of preparatory work has been done in this area. I had an undergraduate student project at Glasgow University this year. He has done excellent refactoring work and we should be able to build on this to get a fully functional baseline compiler.referencesWhen my student's project is marked, I will put a PDF document up here. In the mean time, here is an out of date thesis about an earlier porting effort to ARM.needed skillsJava, willingness to deal with low-level details, familiarity with ARM instruction setdifficultymoderate to difficultinterested mentorJeremy Singer, also support available from colleagues at ARM directly. Please get in touch to discuss details!  Project TitleImplement new Quick compilerRVM areacompilersoutlineA Quick Compiler that does simple optimization and some use of registers, possibly modeled after existing dynamic code generation systems such as that of QEMU or valgrind. The point of such a compiler is to exploit "low hanging fruit". Previous work (10 years ago) took a somewhat different approach, but suggested that a compiler that applied a simple approach to register allocation and some simple optimizations reduced total execution over the current Baseline or Baseline+Opt compilation systems.referencesQEMU and valgrind are good starting points for developing the compilation / optimization strategy.needed skillscompiler expertise (analyses and optimizations)difficultymoderate to difficultinterested mentorEliot Moss  Project TitleReengineer Command Line Flag parsing in Jikes RVMRVM areainfrastructureoutlineJikes RVM has lots of command-line flags, as you can see from the command line help. Researchers add new flags all the time, when they are working on experimental features. The current techniques for adding new flags, parsing flags, etc is quite complex. This project is about refactoring the code to make command line flag handling more straightforward. Possibilities (negotiable) include autocomplete for flags, suggestions for unrecognised flags, etc.referencesMaybe look at Google commandline flags library, and at bash completion for some ideas.needed skillsJavadifficultyeasy to moderateinterested mentorJeremy Singer Please get in touch to discuss details! View Online · View Changes Online [Less]

Page edited by Jeremy Singer - "assigning projects to mentors" As in previous years, Jikes RVM will apply to Google Summer of Code for funding for student ... [More] projects.The GSoC 2013 timeline has been published. The first date of importance is: Organization application deadline on March 29 2013Our current task is to collate a set of interesting project proposals and encourage students to apply for GSoC. We can re-use ideas from previous proposals, or come up with totally new ideas.Hints for studentsThe application for mentoring organizations hasn't been opened yet. However, it's not too early to read the Google Summer of Code documentation. Students should read at least the GSoC FAQ and Google's advice for students. There's also a lot of helpful information about GSoC that's provided by mentoring organizations and previous GSoC students (use your favorite search engine to find it).If the Jikes RVM project sounds like it could be a good fit for you, you can already start to get familiar with Jikes RVM. Checkout the source code and read the user guide. Build the Jikes RVM, run some tests and take a look at the codebase. You should have your development environment already set up before applying. Don't hesitate to ask on the mailing lists if you need help.If/when we've been accepted as a mentoring organization, students can take a look at our guidelines on making an application. We expect that students get familiar with the Jikes RVM and the Jikes RVM community before applying.What's in it for me?All mentors get a smart Google t-shirt. The project gets some new contributors, and the students get substantial amounts of cash and experience in open source development. The Jikes RVM project has seen substantial benefits from GSoC in previous years, including a new native threading model and additions to the core team of developers.Adding new project suggestionsPlease add your ideas to the wiki below, ideally using the template shown below. You can also contribute an idea if you don't have a wiki account: just describe it on on the researchers mailing list. Project TitlefooRVM area{compiler, classlib, MMTk, infrastructure...}outlineparagraph description of project ideareferenceslinks to related projects, academic papers, etcneeded skillsskills that the student should have and/or needs to acquire during the projectdifficultya difficulty estimate for the project, e.g. easy, medium, difficultinterested mentoryour name and a contact link or "TBD" if you can't mentorProject suggestions (aka idea list) Project TitleImplement the Java Management extensions (JMX) APIRVM areaclasslib, MMTk, threading, compileroutlineThe Java Management Extensions provide a way to monitor and manage Java Virtual machines. The Jikes RVM can collect significantly more profiling data and runtime statistics than an average JVM as a result of it being focussed on research activities. These statistics would ideally be exported using JMX and could potentially provide a standard mechanism for monitoring the performance and health of the virtual machine and its components.As a first step, students should focus on laying groundwork for a suitable implementation of the API:Update the JMX code from GSoC 2007 (written by Andrew John Hughes) to work with the current Jikes RVMImplement all the parts of the API that are requiredWrite automated tests that can be integrated into our test frameworksAfter that has happened, students should implement the optional parts of the API and Jikes RVM-specific features. The exact set of features will need to be discussed with the community at the appropriate time.referencesBlog post about JMX with links to further documentationOur bugtracker entry for JMXWeb view of the JMX branch in the historic svn repository (use "svn checkout svn://svn.code.sf.net/p/jikesrvm/svn/rvmroot/branches/RVM-127-JMX" to checkout the code)needed skillsJavadifficultyeasyinterested mentorTBD  Project TitleImplement the JVM Tool Interface (JVMTI)RVM areathreading, JNIoutlineThe JVM Tool interface is part of the Java Platform Debugger Architecture that JVMs can implement to provide debugging capabilities. We would like to have a full JMVTI implementation to allow debugging of Java applications that are running on Jikes RVM. Another benefit of JVMTI is that it allows low-level access to JVM internals. This can be used for instrumenting and monitoring the Jikes RVM using low-level code.There is already a partial JMVTI implementation that was written by James Bornholt for GSoC 2011. His implementation should be used as a basis for this project.referencesWriteup of James Bornholt on the GSoC 2011 pageWeb view of previous GSoC 2011 JVMTI workneeded skillsC, C++, Java, willingness to deal with low-level detailsdifficultymediuminterested mentorEliot Moss  Project TitleImprove (or rethink) CatTrackRVM areainfrastructureoutlineThe Jikes RVM project currently uses the Ruby-on-Rails application CatTrack to track test results. CatTrack is also responsible for sending regression mails.This project would consist of upgrading CatTrack to use a more recent version of Ruby-on-Rails instead of the ancient Ruby-on-Rails 1.2.6. Potential candidates must have experience in Ruby-on-Rails to be able to take on this project: we don't have the necessary expertise to provide adequate mentoring to RoR beginners. The exact version numbers and the upgrade process need to be coordinated with our contacts at the Australian National University (where the servers are located). New features can be added to CatTrack after the upgrade is complete.An alternative approach would be to get rid of CatTrack completely and move to a more general open-source solution. Note that this would be a much more disruptive change. A student proposal that suggests this approach must be very convincing to be considered. Another constraint for proposals of this kind is that we want to avoid using yet another language in our build infrastructure (see RVM-85 ). It might be acceptable to replace Ruby with another language but this must be discussed before such a proposal is submitted.The X10 language project also uses CatTrack for their regression mails. Candidates should be prepared to coordinate with somebody from the X10 team to ensure that an upgraded version of CatTrack (or a replacement) is also a viable solution for them.referencesWeb view of the CatTrack repositoryneeded skillsprior Ruby-on-Rails experience, XML, basic knowledge about databasesdifficultydifficultinterested mentorTBD  Project TitleImprove testing situation for JIkes RVMRVM areainfrastructure, (additional subsystems as chosen by the student)outlineAn infrastructure for unit tests and some initial unit tests were added to the Jikes RVM in GSoC 2012 by João Reys Santos. However, there is still a lot of work to do before we can consider the codebase to be reasonably well tested. We need more unit tests as well as more black-box tests.Students should pick an area of interest (e.g. compilers, JNI, MMTk, classloading, threading, ...) and/or motivating use cases (e.g. get benchmark X or application Y running on Jikes RVM), identify and fix the corresponding problems and introduce adequate (unit) tests.Note that extra effort will be required if students want to use mocking. Mockito does not work with GNU Classpath-based JVMs and our OpenJDK-port is not yet ready.referencesbook: Michael Feathers, Working effectively with legacy code, Pearson Education, 2004book: Andreas Zeller, Why programs fail: A guide to systematic debugging, Morgan Kaufmann, 2009needed skillsJava, Ant, debugging without a debuggerdifficultyeasy to difficult (depends on the chosen tasks and areas)interested mentorTBD  Project TitleBytecode verifierRVM areaclassloading, compilersoutlineJikes RVM currently does not implement a bytecode verifier. We would like to have a bytecode verifier that can verify classfiles at least up until Java 6 (we don't support Java 7 yet). The verifier needs to work with the baseline compiler as well as the optimizing compiler. Ideally, it should be possible to use the verifier from the command line without actually running the bytecode that is supposed to be checked. This could be done in a similar way to the OptTestHarness which enables users to control the compilers.The verifier should be designed to support custom verification constraints. Some examples for possible constraints are listed in the JIRA issue linked below.referencesJIRA issue for the bytecode verifierJasmin assembler (useful for creating test cases that trigger verifier errors)Chapter 4 of the JVM Specificationneeded skillsJava, reading papers and specifications, implementing algorithms from specifications and papersdifficultymediuminterested mentorEliot Moss  Project TitleGCspyRVM areaMMTkoutlineThe GCspy framework for garbage collector visualization has become out-of-date and needs improving [RVM-388]. GCSpy 2.0 should update the framework to work properly with the latest version of Jikes RVM. In particular, it should support discontiguous spaces and provide drivers for more of MMTk's GC algorithms. In addition, the rewrite might improve modularity, and possibly integrate with the Eclipse Rich Client Platform.referencesGCspy: an adaptable heap visualisation frameworkneeded skillsJava, C++, willingness to deal with low-level details, some understanding of garbage collectiondifficultyfairly straightforwardinterested mentorRichard Jones  Project TitleImplement the Compressor garbage collectorRVM areaMMTkoutlineA Stop-The-World variant of the Compressor garbage collector was implemented for Jikes RVM in  GSoC 2010 by Michael Gendelman. The goal of this project is to improve the stability of Michael Gendelman's implementation so that it can be merged to mainline. Performance tuning may also be needed.Students that are interested in this project should be familiar with garbage collection and MMTk.Hint for very ambitious students: You can work on more complex variants of the Compressor (e.g. a concurrent version) once the the Stop-The-World variant has been merged and the project has determined that its quality is suitable.referencespaper: Haim Kermanya and Erez Petrank, The Compressor: concurrent, incremental, and parallel compaction (ACM link)JIRA issue for the compressor (includes a link to the paper)Michael Gendelman's work on the Compressor (includes a design document on the wiki)needed skillsJava, willingness to deal with low-level details, familiarity with garbage collectiondifficultydifficultinterested mentorTBD  Project TitlePort Jikes RVM compilers to ARMRVM areacompilersoutlineJikes RVM currently supports 32-bit Intel, and 32- and 64-bit Power PC architectures. This project involves porting Jikes RVM (initially the baseline compiler) to the 32-bit ARM architecture. Ambitious students could consider the optimizing compiler too, as a second step. Lots of preparatory work has been done in this area. I had an undergraduate student project at Glasgow University this year. He has done excellent refactoring work and we should be able to build on this to get a fully functional baseline compiler.referencesWhen my student's project is marked, I will put a PDF document up here. In the mean time, here is an out of date thesis about an earlier porting effort to ARM.needed skillsJava, willingness to deal with low-level details, familiarity with ARM instruction setdifficultymoderate to difficultinterested mentorJeremy Singer, also support available from colleagues at ARM directly. Please get in touch to discuss details!  Project TitleReengineer Command Line Flag parsing in Jikes RVMRVM areainfrastructureoutlineJikes RVM has lots of command-line flags, as you can see from the command line help. Researchers add new flags all the time, when they are working on experimental features. The current techniques for adding new flags, parsing flags, etc is quite complex. This project is about refactoring the code to make command line flag handling more straightforward. Possibilities (negotiable) include autocomplete for flags, suggestions for unrecognised flags, etc.referencesMaybe look at Google commandline flags library, and at bash completion for some ideas.needed skillsJavadifficultyeasy to moderateinterested mentorJeremy Singer Please get in touch to discuss details! View Online · View Changes Online [Less]

Page edited by Jeremy Singer - "refined project description" As in previous years, Jikes RVM will apply to Google Summer of Code for funding for student ... [More] projects.The GSoC 2013 timeline has been published. The first date of importance is: Organization application deadline on March 29 2013Our current task is to collate a set of interesting project proposals and encourage students to apply for GSoC. We can re-use ideas from previous proposals, or come up with totally new ideas.Hints for studentsThe application for mentoring organizations hasn't been opened yet. However, it's not too early to read the Google Summer of Code documentation. Students should read at least the GSoC FAQ and Google's advice for students. There's also a lot of helpful information about GSoC that's provided by mentoring organizations and previous GSoC students (use your favorite search engine to find it).If the Jikes RVM project sounds like it could be a good fit for you, you can already start to get familiar with Jikes RVM. Checkout the source code and read the user guide. Build the Jikes RVM, run some tests and take a look at the codebase. You should have your development environment already set up before applying. Don't hesitate to ask on the mailing lists if you need help.If/when we've been accepted as a mentoring organization, students can take a look at our guidelines on making an application. We expect that students get familiar with the Jikes RVM and the Jikes RVM community before applying.What's in it for me?All mentors get a smart Google t-shirt. The project gets some new contributors, and the students get substantial amounts of cash and experience in open source development. The Jikes RVM project has seen substantial benefits from GSoC in previous years, including a new native threading model and additions to the core team of developers.Adding new project suggestionsPlease add your ideas to the wiki below, ideally using the template shown below. You can also contribute an idea if you don't have a wiki account: just describe it on on the researchers mailing list. Project TitlefooRVM area{compiler, classlib, MMTk, infrastructure...}outlineparagraph description of project ideareferenceslinks to related projects, academic papers, etcneeded skillsskills that the student should have and/or needs to acquire during the projectdifficultya difficulty estimate for the project, e.g. easy, medium, difficultinterested mentoryour name and a contact link or "TBD" if you can't mentorProject suggestions (aka idea list) Project TitleImplement the Java Management extensions (JMX) APIRVM areaclasslib, MMTk, threading, compileroutlineThe Java Management Extensions provide a way to monitor and manage Java Virtual machines. The Jikes RVM can collect significantly more profiling data and runtime statistics than an average JVM as a result of it being focussed on research activities. These statistics would ideally be exported using JMX and could potentially provide a standard mechanism for monitoring the performance and health of the virtual machine and its components.As a first step, students should focus on laying groundwork for a suitable implementation of the API:Update the JMX code from GSoC 2007 (written by Andrew John Hughes) to work with the current Jikes RVMImplement all the parts of the API that are requiredWrite automated tests that can be integrated into our test frameworksAfter that has happened, students should implement the optional parts of the API and Jikes RVM-specific features. The exact set of features will need to be discussed with the community at the appropriate time.referencesBlog post about JMX with links to further documentationOur bugtracker entry for JMXWeb view of the JMX branch in the historic svn repository (use "svn checkout svn://svn.code.sf.net/p/jikesrvm/svn/rvmroot/branches/RVM-127-JMX" to checkout the code)needed skillsJavadifficultyeasyinterested mentorTBD  Project TitleImplement the JVM Tool Interface (JVMTI)RVM areathreading, JNIoutlineThe JVM Tool interface is part of the Java Platform Debugger Architecture that JVMs can implement to provide debugging capabilities. We would like to have a full JMVTI implementation to allow debugging of Java applications that are running on Jikes RVM. Another benefit of JVMTI is that it allows low-level access to JVM internals. This can be used for instrumenting and monitoring the Jikes RVM using low-level code.There is already a partial JMVTI implementation that was written by James Bornholt for GSoC 2011. His implementation should be used as a basis for this project.referencesWriteup of James Bornholt on the GSoC 2011 pageWeb view of previous GSoC 2011 JVMTI workneeded skillsC, C++, Java, willingness to deal with low-level detailsdifficultymediuminterested mentorTBD  Project TitleImprove (or rethink) CatTrackRVM areainfrastructureoutlineThe Jikes RVM project currently uses the Ruby-on-Rails application CatTrack to track test results. CatTrack is also responsible for sending regression mails.This project would consist of upgrading CatTrack to use a more recent version of Ruby-on-Rails instead of the ancient Ruby-on-Rails 1.2.6. Potential candidates must have experience in Ruby-on-Rails to be able to take on this project: we don't have the necessary expertise to provide adequate mentoring to RoR beginners. The exact version numbers and the upgrade process need to be coordinated with our contacts at the Australian National University (where the servers are located). New features can be added to CatTrack after the upgrade is complete.An alternative approach would be to get rid of CatTrack completely and move to a more general open-source solution. Note that this would be a much more disruptive change. A student proposal that suggests this approach must be very convincing to be considered. Another constraint for proposals of this kind is that we want to avoid using yet another language in our build infrastructure (see RVM-85 ). It might be acceptable to replace Ruby with another language but this must be discussed before such a proposal is submitted.The X10 language project also uses CatTrack for their regression mails. Candidates should be prepared to coordinate with somebody from the X10 team to ensure that an upgraded version of CatTrack (or a replacement) is also a viable solution for them.referencesWeb view of the CatTrack repositoryneeded skillsprior Ruby-on-Rails experience, XML, basic knowledge about databasesdifficultydifficultinterested mentorTBD  Project TitleImprove testing situation for JIkes RVMRVM areainfrastructure, (additional subsystems as chosen by the student)outlineAn infrastructure for unit tests and some initial unit tests were added to the Jikes RVM in GSoC 2012 by João Reys Santos. However, there is still a lot of work to do before we can consider the codebase to be reasonably well tested. We need more unit tests as well as more black-box tests.Students should pick an area of interest (e.g. compilers, JNI, MMTk, classloading, threading, ...) and/or motivating use cases (e.g. get benchmark X or application Y running on Jikes RVM), identify and fix the corresponding problems and introduce adequate (unit) tests.Note that extra effort will be required if students want to use mocking. Mockito does not work with GNU Classpath-based JVMs and our OpenJDK-port is not yet ready.referencesbook: Michael Feathers, Working effectively with legacy code, Pearson Education, 2004book: Andreas Zeller, Why programs fail: A guide to systematic debugging, Morgan Kaufmann, 2009needed skillsJava, Ant, debugging without a debuggerdifficultyeasy to difficult (depends on the chosen tasks and areas)interested mentorTBD  Project TitleBytecode verifierRVM areaclassloading, compilersoutlineJikes RVM currently does not implement a bytecode verifier. We would like to have a bytecode verifier that can verify classfiles at least up until Java 6 (we don't support Java 7 yet). The verifier needs to work with the baseline compiler as well as the optimizing compiler. Ideally, it should be possible to use the verifier from the command line without actually running the bytecode that is supposed to be checked. This could be done in a similar way to the OptTestHarness which enables users to control the compilers.The verifier should be designed to support custom verification constraints. Some examples for possible constraints are listed in the JIRA issue linked below.referencesJIRA issue for the bytecode verifierJasmin assembler (useful for creating test cases that trigger verifier errors)Chapter 4 of the JVM Specificationneeded skillsJava, reading papers and specifications, implementing algorithms from specifications and papersdifficultymediuminterested mentorTBD  Project TitleGCspyRVM areaMMTkoutlineThe GCspy framework for garbage collector visualization has become out-of-date and needs improving [RVM-388]. GCSpy 2.0 should update the framework to work properly with the latest version of Jikes RVM. In particular, it should support discontiguous spaces and provide drivers for more of MMTk's GC algorithms. In addition, the rewrite might improve modularity, and possibly integrate with the Eclipse Rich Client Platform.referencesGCspy: an adaptable heap visualisation frameworkneeded skillsJava, C++, willingness to deal with low-level details, some understanding of garbage collectiondifficultyfairly straightforwardinterested mentorRichard Jones  Project TitleImplement the Compressor garbage collectorRVM areaMMTkoutlineA Stop-The-World variant of the Compressor garbage collector was implemented for Jikes RVM in  GSoC 2010 by Michael Gendelman. The goal of this project is to improve the stability of Michael Gendelman's implementation so that it can be merged to mainline. Performance tuning may also be needed.Students that are interested in this project should be familiar with garbage collection and MMTk.Hint for very ambitious students: You can work on more complex variants of the Compressor (e.g. a concurrent version) once the the Stop-The-World variant has been merged and the project has determined that its quality is suitable.referencespaper: Haim Kermanya and Erez Petrank, The Compressor: concurrent, incremental, and parallel compaction (ACM link)JIRA issue for the compressor (includes a link to the paper)Michael Gendelman's work on the Compressor (includes a design document on the wiki)needed skillsJava, willingness to deal with low-level details, familiarity with garbage collectiondifficultydifficultinterested mentorTBD  Project TitlePort Jikes RVM compilers to ARMRVM areacompilersoutlineJikes RVM currently supports 32-bit Intel, and 32- and 64-bit Power PC architectures. This project involves porting Jikes RVM (initially the baseline compiler) to the 32-bit ARM architecture. Ambitious students could consider the optimizing compiler too, as a second step. Lots of preparatory work has been done in this area. I had an undergraduate student project at Glasgow University this year. He has done excellent refactoring work and we should be able to build on this to get a fully functional baseline compiler.referencesWhen my student's project is marked, I will put a PDF document up here. In the mean time, here is an out of date thesis about an earlier porting effort to ARM.needed skillsJava, willingness to deal with low-level details, familiarity with ARM instruction setdifficultymoderate to difficultinterested mentorJeremy Singer, also support available from colleagues at ARM directly. Please get in touch to discuss details!  Project TitleReengineer Command Line Flag parsing in Jikes RVMRVM areainfrastructureoutlineJikes RVM has lots of command-line flags, as you can see from the command line help. Researchers add new flags all the time, when they are working on experimental features. The current techniques for adding new flags, parsing flags, etc is quite complex. This project is about refactoring the code to make command line flag handling more straightforward. Possibilities (negotiable) include autocomplete for flags, suggestions for unrecognised flags, etc.referencesMaybe look at Google commandline flags library, and at bash completion for some ideas.needed skillsJavadifficultyeasy to moderateinterested mentorJeremy Singer Please get in touch to discuss details! View Online · View Changes Online [Less]