org.mmtk.plan.semispace.gcspy

Class SSGCspy

java.lang.Object

org.mmtk.plan.Plan

org.mmtk.plan.Simple

org.mmtk.plan.StopTheWorld

org.mmtk.plan.semispace.SS

org.mmtk.plan.semispace.gcspy.SSGCspy

All Implemented Interfaces:

GCspyPlan

public class SSGCspy
extends SS
implements GCspyPlan

This class extends a simple semi-space collector to instrument it for GCspy.

See the Jones & Lins GC book, section 2.2 for an overview of the basic algorithm. This implementation also includes a large object space (LOS), and an uncollected "immortal" space.

All plans make a clear distinction between global and thread-local activities. Global activities must be synchronized, whereas no synchronization is required for thread-local activities. Instances of Plan map 1:1 to "kernel threads" (aka CPUs). Thus instance methods allow fast, unsychronized access to Plan utilities such as allocation and collection. Each instance rests on static resources (such as memory and virtual memory resources) which are "global" and therefore "static" members of Plan. This mapping of threads to instances is crucial to understanding the correctness and performance proprties of this plan.

FIXME This seems to have changed The order of phases and GCspy actions is important here. It is:

   PREPARE phase
      SSGCspyMutator.gcspyGatherData(SSGCspy.BEFORE_COLLECTION); // safepoint
      SSMutator.PREPARE // FIXME DOES NOT ss.rebind(SS.toSpace());

   PREPARE phase
      SS.PREPARE // flip semispaces
      gcspySpace.prepare();
      SSGCspyCollector.gcspyGatherData(SSGCspy.BEFORE_COLLECTION);
      SSCollector.PREPARE // ss.rebind(SS.toSpace());


   FORWARD_FINALIZABLE phase
      SSCollector.FORWARD_FINALIZABLE
      SSGCspyCollector.gcspyGatherData(SSGCspy.SEMISPACE_COPIED);

   RELEASE phase
      SSGCspyMutator.gcspyGatherData(SSGCspy.SEMISPACE_COPIED); // safepoint
      SSMutator.RELEASE // FIXME ss.rebind(SS.toSpace());
      SSGCspyMutator.gcspyGatherData(SSGCspy.AFTER_COLLECTION);

   RELEASE phase
      SSCollector.RELEASE
      SSGCspyCollector.gcspyGatherData(SSGCspy.AFTER_COLLECTION);
      SS.RELEASE
      gcspySpace.release();
      SSGCspy.gcspyGatherData(); // safepoint

Note that SSMutator has changed the point at which it rebinds toSpace from PREPARE (2.4.6) to after RELEASE (3.x.x).

 --Phase Collector.initiate
 --Phase Mutator.initiate-mutator
 --Phase Mutator.prepare-mutator
     SSGCspyMutator.gcspyGatherData, event=0
 --Phase Plan.prepare
 --Phase Collector.prepare
     SSGCspyCollector.gcspyGatherData, event=0
 --Phase Collector.bootimage-root
 --Phase Collector.root
 --Phase Plan.root
 --Phase Collector.start-closure
 --Phase Collector.soft-ref
 --Phase Collector.complete-closure
 --Phase Collector.weak-ref
 --Phase Collector.finalize
 --Phase Collector.complete-closure
 --Phase Collector.phantom-ref
 --Phase Collector.forward-ref
 --Phase Collector.forward-finalize
     SSGCspyCollector.gcspyGatherData, event=1
 --Phase Mutator.release-mutator
     SSGCspyMutator.gcspyGatherData, event=1
     SSGCspyMutator.gcspyGatherData, event=2
 --Phase Collector.release
     SSGCspyCollector.gcspyGatherData, event=2
 --Phase Plan.release
     SSGCspy.gcspyGatherData, event=2
 --Phase Collector.complete
 --Phase Plan.complete
 

Field Summary

Fields

Modifier and Type	Field and Description
(package private) static int	AFTER_COLLECTION The collection is complete, i.e. immediately after SS.collectionPhase(SS.RELEASE,..).
(package private) static int	BEFORE_COLLECTION Before a collection has started, i.e. before SS.collectionPhase(SS.PREPARE,..).
private static boolean	DEBUG
(package private) static int	gcspyEvent_
(package private) static ImmortalSpaceDriver	immortalDriver
(package private) static TreadmillDriver	losDriver
(package private) static TreadmillDriver	losNurseryDriver
(package private) static TreadmillDriver	plosDriver
(package private) static TreadmillDriver	plosNurseryDriver
(package private) static int	SEMISPACE_COPIED After the semispace has been copied and the large object space has been traced At this time the Large Object Space has not been swept.
(package private) static LinearSpaceDriver	ss0Driver
(package private) static LinearSpaceDriver	ss1Driver

Fields inherited from class org.mmtk.plan.semispace.SS

ALLOC_SS, copySpace0, copySpace1, hi, SCAN_SS, SS0, SS1, ssTrace

Fields inherited from class org.mmtk.plan.StopTheWorld

postSanityPhase, preSanityPhase

Fields inherited from class org.mmtk.plan.Simple

CLOSURE, collection, collectionAttempt, COMPLETE, completeClosurePhase, FINALIZABLE, finishPhase, FORWARD, FORWARD_FINALIZABLE, FORWARD_REFS, forwardPhase, INITIATE, initPhase, PHANTOM_REFS, POST_SANITY_PLACEHOLDER, PRE_SANITY_PLACEHOLDER, PREPARE, PREPARE_STACKS, prepareStacks, refTypeClosurePhase, RELEASE, rootClosurePhase, ROOTS, SANITY_BUILD_TABLE, SANITY_CHECK_TABLE, SANITY_COPY_ROOTS, SANITY_PREPARE, SANITY_RELEASE, SANITY_ROOTS, SANITY_SET_POSTGC, SANITY_SET_PREGC, sanityBuildPhase, sanityCheckPhase, SET_COLLECTION_KIND, SOFT_REFS, STACK_ROOTS, WEAK_REFS, WEAK_TRACK_REFS

Fields inherited from class org.mmtk.plan.Plan

ALLOC_CODE, ALLOC_COLD_CODE, ALLOC_DEFAULT, ALLOC_GCSPY, ALLOC_HOT_CODE, ALLOC_IMMORTAL, ALLOC_LARGE_CODE, ALLOC_LOS, ALLOC_NON_MOVING, ALLOC_NON_REFERENCE, ALLOC_PRIMITIVE_LOS, ALLOC_STACK, allocationSiteCount, ALLOCATORS, concurrentWorkers, controlCollectorContext, DEFAULT_MAX_NURSERY, DEFAULT_MIN_NURSERY, DEFAULT_SITE, defaultCollectorContext, emergencyCollection, GATHER_WRITE_BARRIER_STATS, GC_PREPARE, GC_PROPER, IMMORTAL, immortalSpace, insideHarness, internalTriggeredCollection, LARGE_CODE, largeCodeSpace, lastInternalTriggeredCollection, LOS, loSpace, MAX_NON_LOS_COPY_BYTES, MAX_NON_LOS_DEFAULT_ALLOC_BYTES, MAX_NON_LOS_NONMOVING_ALLOC_BYTES, META, metaDataSpace, NEEDS_LOG_BIT_IN_HEADER, NON_MOVING, NON_PARTICIPANT, nonMovingSpace, NOT_IN_GC, parallelWorkers, pretenureThreshold, SANITY, sanityChecker, sanitySpace, SCAN_BOOT_IMAGE, SMALL_CODE, smallCodeSpace, stacksPrepared, totalTime, USE_CODE_SPACE, userTriggeredCollection, VM_SPACE, vmSpace

Fields inherited from interface org.mmtk.plan.GCspyPlan

GCSPY, gcspySpace

Constructor Summary

Constructors

Constructor and Description
SSGCspy()

Method Summary

Modifier and Type	Method and Description
void	collectionPhase(short phaseId) Perform a (global) collection phase.
private void	gcspyGatherData(int event) Gather data for GCspy for the semispaces, the immortal space and the large object space.
int	getPagesUsed() Return the number of pages reserved for use given the pending allocation.
private LinearSpaceDriver	newLinearSpaceDriver(String name, CopySpace space, boolean mainSpace) Create a new LinearSpaceDriver TODO is this the best name or should we call it LargeObjectSpaceDriver?
private TreadmillDriver	newTreadmillDriver(String name, LargeObjectSpace space) Create a new TreadmillDriver TODO is this the best name or should we call it LargeObjectSpaceDriver?
protected void	registerSpecializedMethods() Registers specialized methods.
(package private) static void	reportSpaces() Report information on the semispaces
void	startGCspyServer(int port, boolean wait) Start the server and wait if necessary.

Methods inherited from class org.mmtk.plan.semispace.SS

fromSpace, getCollectionReserve, getPagesAvail, toSpace, willNeverMove

Methods inherited from class org.mmtk.plan.StopTheWorld

processOptions

Methods inherited from class org.mmtk.plan.Simple

replacePhase, replacePlaceholderPhase, switchNurseryZeroingApproach

Methods inherited from class org.mmtk.plan.Plan

availableMemory, bootTimeWriteBarrier, collectionRequired, concurrentCollectionRequired, determineThreadCount, enableAllocation, enableCollection, forceFullHeapCollection, freeMemory, fullyBooted, gcInProgress, gcInProgressProper, getAllocationSite, getPagesReserved, getSpecializedScanClass, getTotalPages, handleUserCollectionRequest, harnessBegin, harnessEnd, insertPhaseAfter, isCurrentGCNursery, isEmergencyCollection, isInitialized, isInternalTriggeredCollection, isUserTriggeredCollection, lastCollectionFullHeap, lastCollectionWasExhaustive, loadObjectReference, logPoll, notifyExit, poll, preCollectorSpawn, printDetailedTiming, printPostStats, printPreStats, printUsedPages, reservedMemory, resetCollectionTrigger, sanityExpectedRC, sanityLinearScan, setBuildTimeGCByte, setGCStatus, spawnCollectorThreads, stacksPrepared, storeObjectReference, stressTestGCRequired, totalMemory, triggerInternalCollectionRequest, usedMemory

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BEFORE_COLLECTION

static final int BEFORE_COLLECTION

Before a collection has started, i.e. before SS.collectionPhase(SS.PREPARE,..).

See Also:

Constant Field Values

SEMISPACE_COPIED

static final int SEMISPACE_COPIED

After the semispace has been copied and the large object space has been traced At this time the Large Object Space has not been swept.

See Also:

Constant Field Values

AFTER_COLLECTION

static final int AFTER_COLLECTION

The collection is complete, i.e. immediately after SS.collectionPhase(SS.RELEASE,..). The Large Object Space has been swept.

See Also:

Constant Field Values

gcspyEvent_

static int gcspyEvent_

ss0Driver

static LinearSpaceDriver ss0Driver

ss1Driver

static LinearSpaceDriver ss1Driver

immortalDriver

static ImmortalSpaceDriver immortalDriver

losNurseryDriver

static TreadmillDriver losNurseryDriver

losDriver

static TreadmillDriver losDriver

plosNurseryDriver

static TreadmillDriver plosNurseryDriver

plosDriver

static TreadmillDriver plosDriver

DEBUG

private static final boolean DEBUG

See Also:

Constant Field Values

Constructor Detail

SSGCspy

public SSGCspy()

Method Detail

startGCspyServer

public final void startGCspyServer(int port,
                                   boolean wait)

Start the server and wait if necessary. This method has the following responsibilities.

1. Create and initialise the GCspy server by calling.

   server = ServerInterpreter.init(name, portNumber, verbose);

2. Add each event to the ServerInterpreter

   server.addEvent(eventID, eventName);

3. Set some general information about the server (e.g. name of the collector, build, etc).

   server.setGeneralInfo(info); 

4. Create new drivers for each component to be visualised.

   myDriver = new MyDriver(server, args...);

   Drivers extend AbstractDriver and register their spce with the ServerInterpreter. In addition to the server, drivers will take as arguments the name of the space, the MMTk space, the tilesize, and whether this space is to be the main space in the visualiser.

WARNING: allocates memory.

Overrides:

startGCspyServer in class Plan

Parameters:

wait - Whether to wait

port - The port to talk to the GCspy client (e.g. visualiser)

newLinearSpaceDriver

private LinearSpaceDriver newLinearSpaceDriver(String name,
                                               CopySpace space,
                                               boolean mainSpace)

Create a new LinearSpaceDriver TODO is this the best name or should we call it LargeObjectSpaceDriver?

Parameters:

name - Name of the space

space - The space

mainSpace - whether the space will be the main space

Returns:

A new GCspy driver for this space

newTreadmillDriver

private TreadmillDriver newTreadmillDriver(String name,
                                           LargeObjectSpace space)

Create a new TreadmillDriver TODO is this the best name or should we call it LargeObjectSpaceDriver?

Parameters:

name - Name of the space

space - The space

Returns:

A new GCspy driver for this space

collectionPhase

public void collectionPhase(short phaseId)

Perform a (global) collection phase.

Overrides:

collectionPhase in class SS

Parameters:

phaseId - The unique id of the phase to perform.

gcspyGatherData

private void gcspyGatherData(int event)

Gather data for GCspy for the semispaces, the immortal space and the large object space.

This method sweeps the semispace under consideration to gather data. Alternatively and more efficiently, 'used space' can obviously be discovered in constant time simply by comparing the start and the end addresses of the semispace. However, per-object information can only be gathered by sweeping through the space and we do this here for tutorial purposes.

Parameters:

event - The event, either BEFORE_COLLECTION, SEMISPACE_COPIED or AFTER_COLLECTION

getPagesUsed

public final int getPagesUsed()

Return the number of pages reserved for use given the pending allocation. This is exclusive of space reserved for copying.

Overrides:

getPagesUsed in class SS

Returns:

The number of pages reserved given the pending allocation, excluding space reserved for copying.

reportSpaces

static void reportSpaces()

Report information on the semispaces

registerSpecializedMethods

protected void registerSpecializedMethods()

Description copied from class: Plan

Registers specialized methods.

Overrides:

registerSpecializedMethods in class SS