/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Garbage-collecting memory allocator.
*/
#include "Dalvik.h"
#include "alloc/HeapBitmap.h"
#include "alloc/Verify.h"
#include "alloc/HeapTable.h"
#include "alloc/Heap.h"
#include "alloc/HeapInternal.h"
#include "alloc/DdmHeap.h"
#include "alloc/HeapSource.h"
#include "alloc/MarkSweep.h"
#include "alloc/Visit.h"
#include "utils/threads.h" // need Android thread priorities
#define kInvalidPriority 10000
#include <cutils/sched_policy.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <limits.h>
#include <errno.h>
static const char* GcReasonStr[] = {
[GC_FOR_MALLOC] = "GC_FOR_MALLOC",
[GC_CONCURRENT] = "GC_CONCURRENT",
[GC_EXPLICIT] = "GC_EXPLICIT",
[GC_EXTERNAL_ALLOC] = "GC_EXTERNAL_ALLOC",
[GC_HPROF_DUMP_HEAP] = "GC_HPROF_DUMP_HEAP"
};
/*
* Initialize the GC heap.
*
* Returns true if successful, false otherwise.
*/
bool dvmHeapStartup()
{
GcHeap *gcHeap;
#if defined(WITH_ALLOC_LIMITS)
gDvm.checkAllocLimits = false;
gDvm.allocationLimit = -1;
#endif
gcHeap = dvmHeapSourceStartup(gDvm.heapSizeStart, gDvm.heapSizeMax);
if (gcHeap == NULL) {
return false;
}
gcHeap->heapWorkerCurrentObject = NULL;
gcHeap->heapWorkerCurrentMethod = NULL;
gcHeap->heapWorkerInterpStartTime = 0LL;
gcHeap->ddmHpifWhen = 0;
gcHeap->ddmHpsgWhen = 0;
gcHeap->ddmHpsgWhat = 0;
gcHeap->ddmNhsgWhen = 0;
gcHeap->ddmNhsgWhat = 0;
#if WITH_HPROF
gcHeap->hprofDumpOnGc = false;
gcHeap->hprofContext = NULL;
#endif
gDvm.gcHeap = gcHeap;
/* Set up the lists and lock we'll use for finalizable
* and reference objects.
*/
dvmInitMutex(&gDvm.heapWorkerListLock);
gcHeap->finalizableRefs = NULL;
gcHeap->pendingFinalizationRefs = NULL;
gcHeap->referenceOperations = NULL;
if (!dvmCardTableStartup()) {
LOGE_HEAP("card table startup failed.");
return false;
}
/* Initialize the HeapWorker locks and other state
* that the GC uses.
*/
dvmInitializeHeapWorkerState();
return true;
}
bool dvmHeapStartupAfterZygote(void)
{
return dvmHeapSourceStartupAfterZygote();
}
void dvmHeapShutdown()
{
//TODO: make sure we're locked
if (gDvm.gcHeap != NULL) {
dvmCardTableShutdown();
/* Tables are allocated on the native heap; they need to be
* cleaned up explicitly. The process may stick around, so we
* don't want to leak any native memory.
*/
dvmHeapFreeLargeTable(gDvm.gcHeap->finalizableRefs);
gDvm.gcHeap->finalizableRefs = NULL;
dvmHeapFreeLargeTable(gDvm.gcHeap->pendingFinalizationRefs);
gDvm.gcHeap->pendingFinalizationRefs = NULL;
dvmHeapFreeLargeTable(gDvm.gcHeap->referenceOperations);
gDvm.gcHeap->referenceOperations = NULL;
/* Destroy the heap. Any outstanding pointers will point to
* unmapped memory (unless/until someone else maps it). This
* frees gDvm.gcHeap as a side-effect.
*/
dvmHeapSourceShutdown(&gDvm.gcHeap);
}
}
/*
* Shutdown any threads internal to the heap.
*/
void dvmHeapThreadShutdown(void)
{
dvmHeapSourceThreadShutdown();
}
/*
* We've been asked to allocate something we can't, e.g. an array so
* large that (length * elementWidth) is larger than 2^31.
*
* _The Java Programming Language_, 4th edition, says, "you can be sure
* that all SoftReferences to softly reachable objects will be cleared
* before an OutOfMemoryError is thrown."
*
* It's unclear whether that holds for all situations where an OOM can
* be thrown, or just in the context of an allocation that fails due
* to lack of heap space. For simplicity we just throw the exception.
*
* (OOM due to actually running out of space is handled elsewhere.)
*/
void dvmThrowBadAllocException(const char* msg)
{
dvmThrowException("Ljava/lang/OutOfMemoryError;", msg);
}
/*
* Grab the lock, but put ourselves into THREAD_VMWAIT if it looks like
* we're going to have to wait on the mutex.
*/
bool dvmLockHeap()
{
if (dvmTryLockMutex(&gDvm.gcHeapLock) != 0) {
Thread *self;
ThreadStatus oldStatus;
self = dvmThreadSelf();
oldStatus = dvmChangeStatus(self, THREAD_VMWAIT);
dvmLockMutex(&gDvm.gcHeapLock);
dvmChangeStatus(self, oldStatus);
}
return true;
}
void dvmUnlockHeap()
{
dvmUnlockMutex(&gDvm.gcHeapLock);
}
/* Pop an object from the list of pending finalizations and
* reference clears/enqueues, and return the object.
* The caller must call dvmReleaseTrackedAlloc()
* on the object when finished.
*
* Typically only called by the heap worker thread.
*/
Object *dvmGetNextHeapWorkerObject(HeapWorkerOperation *op)
{
Object *obj;
GcHeap *gcHeap = gDvm.gcHeap;
assert(op != NULL);
dvmLockMutex(&gDvm.heapWorkerListLock);
obj = dvmHeapGetNextObjectFromLargeTable(&gcHeap->referenceOperations);
if (obj != NULL) {
*op = WORKER_ENQUEUE;
} else {
obj = dvmHeapGetNextObjectFromLargeTable(
&gcHeap->pendingFinalizationRefs);
if (obj != NULL) {
*op = WORKER_FINALIZE;
}
}
if (obj != NULL) {
/* Don't let the GC collect the object until the
* worker thread is done with it.
*/
dvmAddTrackedAlloc(obj, NULL);
}
dvmUnlockMutex(&gDvm.heapWorkerListLock);
return obj;
}
/* Do a full garbage collection, which may grow the
* heap as a side-effect if the live set is large.
*/
static void gcForMalloc(bool collectSoftReferences)
{
if (gDvm.allocProf.enabled) {
Thread* self = dvmThreadSelf();
gDvm.allocProf.gcCount++;
if (self != NULL) {
self->allocProf.gcCount++;
}
}
/* This may adjust the soft limit as a side-effect.
*/
LOGD_HEAP("dvmMalloc initiating GC%s\n",
collectSoftReferences ? "(collect SoftReferences)" : "");
dvmCollectGarbageInternal(collectSoftReferences, GC_FOR_MALLOC);
}
/* Try as hard as possible to allocate some memory.
*/
static void *tryMalloc(size_t size)
{
void *ptr;
/* Don't try too hard if there's no way the allocation is
* going to succeed. We have to collect SoftReferences before
* throwing an OOME, though.
*/
if (size >= gDvm.heapSizeMax) {
LOGW_HEAP("dvmMalloc(%zu/0x%08zx): "
"someone's allocating a huge buffer\n", size, size);
ptr = NULL;
goto collect_soft_refs;
}
//TODO: figure out better heuristics
// There will be a lot of churn if someone allocates a bunch of
// big objects in a row, and we hit the frag case each time.
// A full GC for each.
// Maybe we grow the heap in bigger leaps
// Maybe we skip the GC if the size is large and we did one recently
// (number of allocations ago) (watch for thread effects)
// DeflateTest allocs a bunch of ~128k buffers w/in 0-5 allocs of each other
// (or, at least, there are only 0-5 objects swept each time)
ptr = dvmHeapSourceAlloc(size);
if (ptr != NULL) {
return ptr;
}
/*
* The allocation failed. If the GC is running, block until it
* completes and retry.
*/
if (gDvm.gcHeap->gcRunning) {
/*
* The GC is concurrently tracing the heap. Release the heap
* lock, wait for the GC to complete, and retrying allocating.
*/
dvmWaitForConcurrentGcToComplete();
ptr = dvmHeapSourceAlloc(size);
if (ptr != NULL) {
return ptr;
}
}
/*
* Another failure. Our thread was starved or there may be too
* many live objects. Try a foreground GC. This will have no
* effect if the concurrent GC is already running.
*/
gcForMalloc(false);
ptr = dvmHeapSourceAlloc(size);
if (ptr != NULL) {
return ptr;
}
/* Even that didn't work; this is an exceptional state.
* Try harder, growing the heap if necessary.
*/
ptr = dvmHeapSourceAllocAndGrow(size);
if (ptr != NULL) {
size_t newHeapSize;
newHeapSize = dvmHeapSourceGetIdealFootprint();
//TODO: may want to grow a little bit more so that the amount of free
// space is equal to the old free space + the utilization slop for
// the new allocation.
LOGI_HEAP("Grow heap (frag case) to "
"%zu.%03zuMB for %zu-byte allocation\n",
FRACTIONAL_MB(newHeapSize), size);
return ptr;
}
/* Most allocations should have succeeded by now, so the heap
* is really full, really fragmented, or the requested size is
* really big. Do another GC, collecting SoftReferences this
* time. The VM spec requires that all SoftReferences have
* been collected and cleared before throwing an OOME.
*/
//TODO: wait for the finalizers from the previous GC to finish
collect_soft_refs:
LOGI_HEAP("Forcing collection of SoftReferences for %zu-byte allocation\n",
size);
gcForMalloc(true);
ptr = dvmHeapSourceAllocAndGrow(size);
if (ptr != NULL) {
return ptr;
}
//TODO: maybe wait for finalizers and try one last time
LOGE_HEAP("Out of memory on a %zd-byte allocation.\n", size);
//TODO: tell the HeapSource to dump its state
dvmDumpThread(dvmThreadSelf(), false);
return NULL;
}
/* Throw an OutOfMemoryError if there's a thread to attach it to.
* Avoid recursing.
*
* The caller must not be holding the heap lock, or else the allocations
* in dvmThrowException() will deadlock.
*/
static void throwOOME()
{
Thread *self;
if ((self = dvmThreadSelf()) != NULL) {
/* If the current (failing) dvmMalloc() happened as part of thread
* creation/attachment before the thread became part of the root set,
* we can't rely on the thread-local trackedAlloc table, so
* we can't keep track of a real allocated OOME object. But, since
* the thread is in the process of being created, it won't have
* a useful stack anyway, so we may as well make things easier
* by throwing the (stackless) pre-built OOME.
*/
if (dvmIsOnThreadList(self) && !self->throwingOOME) {
/* Let ourselves know that we tried to throw an OOM
* error in the normal way in case we run out of
* memory trying to allocate it inside dvmThrowException().
*/
self->throwingOOME = true;
/* Don't include a description string;
* one fewer allocation.
*/
dvmThrowException("Ljava/lang/OutOfMemoryError;", NULL);
} else {
/*
* This thread has already tried to throw an OutOfMemoryError,
* which probably means that we're running out of memory
* while recursively trying to throw.
*
* To avoid any more allocation attempts, "throw" a pre-built
* OutOfMemoryError object (which won't have a useful stack trace).
*
* Note that since this call can't possibly allocate anything,
* we don't care about the state of self->throwingOOME
* (which will usually already be set).
*/
dvmSetException(self, gDvm.outOfMemoryObj);
}
/* We're done with the possible recursion.
*/
self->throwingOOME = false;
}
}
/*
* Allocate storage on the GC heap. We guarantee 8-byte alignment.
*
* The new storage is zeroed out.
*
* Note that, in rare cases, this could get called while a GC is in
* progress. If a non-VM thread tries to attach itself through JNI,
* it will need to allocate some objects. If this becomes annoying to
* deal with, we can block it at the source, but holding the allocation
* mutex should be enough.
*
* In rare circumstances (JNI AttachCurrentThread) we can be called
* from a non-VM thread.
*
* Use ALLOC_DONT_TRACK when we either don't want to track an allocation
* (because it's being done for the interpreter "new" operation and will
* be part of the root set immediately) or we can't (because this allocation
* is for a brand new thread).
*
* Returns NULL and throws an exception on failure.
*
* TODO: don't do a GC if the debugger thinks all threads are suspended
*/
void* dvmMalloc(size_t size, int flags)
{
GcHeap *gcHeap = gDvm.gcHeap;
void *ptr;
#if defined(WITH_ALLOC_LIMITS)
/*
* See if they've exceeded the allocation limit for this thread.
*
* A limit value of -1 means "no limit".
*
* This is enabled at compile time because it requires us to do a
* TLS lookup for the Thread pointer. This has enough of a performance
* impact that we don't want to do it if we don't have to. (Now that
* we're using gDvm.checkAllocLimits we may want to reconsider this,
* but it's probably still best to just compile the check out of
* production code -- one less thing to hit on every allocation.)
*/
if (gDvm.checkAllocLimits) {
Thread* self = dvmThreadSelf();
if (self != NULL) {
int count = self->allocLimit;
if (count > 0) {
self->allocLimit--;
} else if (count == 0) {
/* fail! */
assert(!gDvm.initializing);
self->allocLimit = -1;
dvmThrowException("Ldalvik/system/AllocationLimitError;",
"thread allocation limit exceeded");
return NULL;
}
}
}
if (gDvm.allocationLimit >= 0) {
assert(!gDvm.initializing);
gDvm.allocationLimit = -1;
dvmThrowException("Ldalvik/system/AllocationLimitError;",
"global allocation limit exceeded");
return NULL;
}
#endif
dvmLockHeap();
/* Try as hard as possible to allocate some memory.
*/
ptr = tryMalloc(size);
if (ptr != NULL) {
/* We've got the memory.
*/
if ((flags & ALLOC_FINALIZABLE) != 0) {
/* This object is an instance of a class that
* overrides finalize(). Add it to the finalizable list.
*/
if (!dvmHeapAddRefToLargeTable(&gcHeap->finalizableRefs,
(Object *)ptr))
{
LOGE_HEAP("dvmMalloc(): no room for any more "
"finalizable objects\n");
dvmAbort();
}
}
if (gDvm.allocProf.enabled) {
Thread* self = dvmThreadSelf();
gDvm.allocProf.allocCount++;
gDvm.allocProf.allocSize += size;
if (self != NULL) {
self->allocProf.allocCount++;
self->allocProf.allocSize += size;
}
}
} else {
/* The allocation failed.
*/
if (gDvm.allocProf.enabled) {
Thread* self = dvmThreadSelf();
gDvm.allocProf.failedAllocCount++;
gDvm.allocProf.failedAllocSize += size;
if (self != NULL) {
self->allocProf.failedAllocCount++;
self->allocProf.failedAllocSize += size;
}
}
}
dvmUnlockHeap();
if (ptr != NULL) {
/*
* If caller hasn't asked us not to track it, add it to the
* internal tracking list.
*/
if ((flags & ALLOC_DONT_TRACK) == 0) {
dvmAddTrackedAlloc(ptr, NULL);
}
} else {
/*
* The allocation failed; throw an OutOfMemoryError.
*/
throwOOME();
}
return ptr;
}
/*
* Returns true iff <obj> points to a valid allocated object.
*/
bool dvmIsValidObject(const Object* obj)
{
/* Don't bother if it's NULL or not 8-byte aligned.
*/
if (obj != NULL && ((uintptr_t)obj & (8-1)) == 0) {
/* Even if the heap isn't locked, this shouldn't return
* any false negatives. The only mutation that could
* be happening is allocation, which means that another
* thread could be in the middle of a read-modify-write
* to add a new bit for a new object. However, that
* RMW will have completed by the time any other thread
* could possibly see the new pointer, so there is no
* danger of dvmIsValidObject() being called on a valid
* pointer whose bit isn't set.
*
* Freeing will only happen during the sweep phase, which
* only happens while the heap is locked.
*/
return dvmHeapSourceContains(obj);
}
return false;
}
size_t dvmObjectSizeInHeap(const Object *obj)
{
return dvmHeapSourceChunkSize(obj);
}
static void verifyRootsAndHeap(void)
{
dvmVerifyRoots();
dvmVerifyBitmap(dvmHeapSourceGetLiveBits());
}
/*
* Initiate garbage collection.
*
* NOTES:
* - If we don't hold gDvm.threadListLock, it's possible for a thread to
* be added to the thread list while we work. The thread should NOT
* start executing, so this is only interesting when we start chasing
* thread stacks. (Before we do so, grab the lock.)
*
* We are not allowed to GC when the debugger has suspended the VM, which
* is awkward because debugger requests can cause allocations. The easiest
* way to enforce this is to refuse to GC on an allocation made by the
* JDWP thread -- we have to expand the heap or fail.
*/
void dvmCollectGarbageInternal(bool clearSoftRefs, GcReason reason)
{
GcHeap *gcHeap = gDvm.gcHeap;
u4 rootSuspend, rootSuspendTime, rootStart, rootEnd;
u4 dirtySuspend, dirtyStart, dirtyEnd;
u4 totalTime;
size_t numObjectsFreed, numBytesFreed;
size_t currAllocated, currFootprint;
size_t extAllocated, extLimit;
size_t percentFree;
GcMode gcMode;
int oldThreadPriority = kInvalidPriority;
/* The heap lock must be held.
*/
if (gcHeap->gcRunning) {
LOGW_HEAP("Attempted recursive GC\n");
return;
}
gcMode = (reason == GC_FOR_MALLOC) ? GC_PARTIAL : GC_FULL;
gcHeap->gcRunning = true;
rootSuspend = dvmGetRelativeTimeMsec();
dvmSuspendAllThreads(SUSPEND_FOR_GC);
rootStart = dvmGetRelativeTimeMsec();
rootSuspendTime = rootStart - rootSuspend;
/*
* If we are not marking concurrently raise the priority of the
* thread performing the garbage collection.
*/
if (reason != GC_CONCURRENT) {
/* Get the priority (the "nice" value) of the current thread. The
* getpriority() call can legitimately return -1, so we have to
* explicitly test errno.
*/
errno = 0;
int priorityResult = getpriority(PRIO_PROCESS, 0);
if (errno != 0) {
LOGI_HEAP("getpriority(self) failed: %s\n", strerror(errno));
} else if (priorityResult > ANDROID_PRIORITY_NORMAL) {
/* Current value is numerically greater than "normal", which
* in backward UNIX terms means lower priority.
*/
if (priorityResult >= ANDROID_PRIORITY_BACKGROUND) {
set_sched_policy(dvmGetSysThreadId(), SP_FOREGROUND);
}
if (setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_NORMAL) != 0) {
LOGI_HEAP("Unable to elevate priority from %d to %d\n",
priorityResult, ANDROID_PRIORITY_NORMAL);
} else {
/* priority elevated; save value so we can restore it later */
LOGD_HEAP("Elevating priority from %d to %d\n",
priorityResult, ANDROID_PRIORITY_NORMAL);
oldThreadPriority = priorityResult;
}
}
}
/* Wait for the HeapWorker thread to block.
* (It may also already be suspended in interp code,
* in which case it's not holding heapWorkerLock.)
*/
dvmLockMutex(&gDvm.heapWorkerLock);
/* Make sure that the HeapWorker thread hasn't become
* wedged inside interp code. If it has, this call will
* print a message and abort the VM.
*/
dvmAssertHeapWorkerThreadRunning();
/* Lock the pendingFinalizationRefs list.
*
* Acquire the lock after suspending so the finalizer
* thread can't block in the RUNNING state while
* we try to suspend.
*/
dvmLockMutex(&gDvm.heapWorkerListLock);
if (gDvm.preVerify) {
LOGV_HEAP("Verifying roots and heap before GC");
verifyRootsAndHeap();
}
dvmMethodTraceGCBegin();
#if WITH_HPROF
/* Set DUMP_HEAP_ON_DDMS_UPDATE to 1 to enable heap dumps
* whenever DDMS requests a heap update (HPIF chunk).
* The output files will appear in /data/misc, which must
* already exist.
* You must define "WITH_HPROF := true" in your buildspec.mk
* and recompile libdvm for this to work.
*
* To enable stack traces for each allocation, define
* "WITH_HPROF_STACK := true" in buildspec.mk. This option slows down
* allocations and also requires 8 additional bytes per object on the
* GC heap.
*/
#define DUMP_HEAP_ON_DDMS_UPDATE 0
#if DUMP_HEAP_ON_DDMS_UPDATE
gcHeap->hprofDumpOnGc |= (gcHeap->ddmHpifWhen != 0);
#endif
if (gcHeap->hprofDumpOnGc) {
char nameBuf[128];
gcHeap->hprofResult = -1;
if (gcHeap->hprofFileName == NULL) {
/* no filename was provided; invent one */
sprintf(nameBuf, "/data/misc/heap-dump-tm%d-pid%d.hprof",
(int) time(NULL), (int) getpid());
gcHeap->hprofFileName = nameBuf;
}
gcHeap->hprofContext = hprofStartup(gcHeap->hprofFileName,
gcHeap->hprofFd, gcHeap->hprofDirectToDdms);
if (gcHeap->hprofContext != NULL) {
hprofStartHeapDump(gcHeap->hprofContext);
}
gcHeap->hprofDumpOnGc = false;
gcHeap->hprofFileName = NULL;
}
#endif
/* Set up the marking context.
*/
if (!dvmHeapBeginMarkStep(gcMode)) {
LOGE_HEAP("dvmHeapBeginMarkStep failed; aborting\n");
dvmAbort();
}
/* Mark the set of objects that are strongly reachable from the roots.
*/
LOGD_HEAP("Marking...");
dvmHeapMarkRootSet();
/* dvmHeapScanMarkedObjects() will build the lists of known
* instances of the Reference classes.
*/
gcHeap->softReferences = NULL;
gcHeap->weakReferences = NULL;
gcHeap->phantomReferences = NULL;
if (reason == GC_CONCURRENT) {
/*
* Resume threads while tracing from the roots. We unlock the
* heap to allow mutator threads to allocate from free space.
*/
rootEnd = dvmGetRelativeTimeMsec();
dvmClearCardTable();
dvmUnlockHeap();
dvmResumeAllThreads(SUSPEND_FOR_GC);
}
/* Recursively mark any objects that marked objects point to strongly.
* If we're not collecting soft references, soft-reachable
* objects will also be marked.
*/
LOGD_HEAP("Recursing...");
dvmHeapScanMarkedObjects();
if (reason == GC_CONCURRENT) {
/*
* Re-acquire the heap lock and perform the final thread
* suspension.
*/
dvmLockHeap();
dirtySuspend = dvmGetRelativeTimeMsec();
dvmSuspendAllThreads(SUSPEND_FOR_GC);
dirtyStart = dvmGetRelativeTimeMsec();
/*
* As no barrier intercepts root updates, we conservatively
* assume all roots may be gray and re-mark them.
*/
dvmHeapReMarkRootSet();
/*
* With the exception of reference objects and weak interned
* strings, all gray objects should now be on dirty cards.
*/
if (gDvm.verifyCardTable) {
dvmVerifyCardTable();
}
/*
* Recursively mark gray objects pointed to by the roots or by
* heap objects dirtied during the concurrent mark.
*/
dvmHeapReScanMarkedObjects();
}
/* All strongly-reachable objects have now been marked.
*/
LOGD_HEAP("Handling soft references...");
if (!clearSoftRefs) {
dvmHandleSoftRefs(&gcHeap->softReferences);
}
dvmClearWhiteRefs(&gcHeap->softReferences);
LOGD_HEAP("Handling weak references...");
dvmClearWhiteRefs(&gcHeap->weakReferences);
/* Once all weak-reachable objects have been taken
* care of, any remaining unmarked objects can be finalized.
*/
LOGD_HEAP("Finding finalizations...");
dvmHeapScheduleFinalizations();
LOGD_HEAP("Handling f-reachable soft references...");
dvmClearWhiteRefs(&gcHeap->softReferences);
LOGD_HEAP("Handling f-reachable weak references...");
dvmClearWhiteRefs(&gcHeap->weakReferences);
/* Any remaining objects that are not pending finalization
* could be phantom-reachable. This will mark any phantom-reachable
* objects, as well as enqueue their references.
*/
LOGD_HEAP("Handling phantom references...");
dvmClearWhiteRefs(&gcHeap->phantomReferences);
#if defined(WITH_JIT)
/*
* Patching a chaining cell is very cheap as it only updates 4 words. It's
* the overhead of stopping all threads and synchronizing the I/D cache
* that makes it expensive.
*
* Therefore we batch those work orders in a queue and go through them
* when threads are suspended for GC.
*/
dvmCompilerPerformSafePointChecks();
#endif
LOGD_HEAP("Sweeping...");
dvmHeapSweepSystemWeaks();
/*
* Live objects have a bit set in the mark bitmap, swap the mark
* and live bitmaps. The sweep can proceed concurrently viewing
* the new live bitmap as the old mark bitmap, and vice versa.
*/
dvmHeapSourceSwapBitmaps();
if (gDvm.postVerify) {
LOGV_HEAP("Verifying roots and heap after GC");
verifyRootsAndHeap();
}
if (reason == GC_CONCURRENT) {
dirtyEnd = dvmGetRelativeTimeMsec();
dvmUnlockHeap();
dvmResumeAllThreads(SUSPEND_FOR_GC);
}
dvmHeapSweepUnmarkedObjects(gcMode, reason == GC_CONCURRENT,
&numObjectsFreed, &numBytesFreed);
LOGD_HEAP("Cleaning up...");
dvmHeapFinishMarkStep();
if (reason == GC_CONCURRENT) {
dvmLockHeap();
}
LOGD_HEAP("Done.");
/* Now's a good time to adjust the heap size, since
* we know what our utilization is.
*
* This doesn't actually resize any memory;
* it just lets the heap grow more when necessary.
*/
if (reason != GC_EXTERNAL_ALLOC) {
dvmHeapSourceGrowForUtilization();
}
currAllocated = dvmHeapSourceGetValue(HS_BYTES_ALLOCATED, NULL, 0);
currFootprint = dvmHeapSourceGetValue(HS_FOOTPRINT, NULL, 0);
#if WITH_HPROF
if (gcHeap->hprofContext != NULL) {
hprofFinishHeapDump(gcHeap->hprofContext);
//TODO: write a HEAP_SUMMARY record
if (hprofShutdown(gcHeap->hprofContext))
gcHeap->hprofResult = 0; /* indicate success */
gcHeap->hprofContext = NULL;
}
#endif
/* Now that we've freed up the GC heap, return any large
* free chunks back to the system. They'll get paged back
* in the next time they're used. Don't do it immediately,
* though; if the process is still allocating a bunch of
* memory, we'll be taking a ton of page faults that we don't
* necessarily need to.
*
* Cancel any old scheduled trims, and schedule a new one.
*/
dvmScheduleHeapSourceTrim(5); // in seconds
dvmMethodTraceGCEnd();
LOGV_HEAP("GC finished");
gcHeap->gcRunning = false;
LOGV_HEAP("Resuming threads");
dvmUnlockMutex(&gDvm.heapWorkerListLock);
dvmUnlockMutex(&gDvm.heapWorkerLock);
if (reason == GC_CONCURRENT) {
/*
* Wake-up any threads that blocked after a failed allocation
* request.
*/
dvmBroadcastCond(&gDvm.gcHeapCond);
}
if (reason != GC_CONCURRENT) {
dirtyEnd = dvmGetRelativeTimeMsec();
dvmResumeAllThreads(SUSPEND_FOR_GC);
if (oldThreadPriority != kInvalidPriority) {
if (setpriority(PRIO_PROCESS, 0, oldThreadPriority) != 0) {
LOGW_HEAP("Unable to reset priority to %d: %s\n",
oldThreadPriority, strerror(errno));
} else {
LOGD_HEAP("Reset priority to %d\n", oldThreadPriority);
}
if (oldThreadPriority >= ANDROID_PRIORITY_BACKGROUND) {
set_sched_policy(dvmGetSysThreadId(), SP_BACKGROUND);
}
}
}
extAllocated = dvmHeapSourceGetValue(HS_EXTERNAL_BYTES_ALLOCATED, NULL, 0);
extLimit = dvmHeapSourceGetValue(HS_EXTERNAL_LIMIT, NULL, 0);
percentFree = 100 - (size_t)(100.0f * (float)currAllocated / currFootprint);
if (reason != GC_CONCURRENT) {
u4 markSweepTime = dirtyEnd - rootStart;
bool isSmall = numBytesFreed > 0 && numBytesFreed < 1024;
totalTime = rootSuspendTime + markSweepTime;
LOGD("%s freed %s%zdK, %d%% free %zdK/%zdK, external %zdK/%zdK, "
"paused %ums",
GcReasonStr[reason],
isSmall ? "<" : "",
numBytesFreed ? MAX(numBytesFreed / 1024, 1) : 0,
percentFree,
currAllocated / 1024, currFootprint / 1024,
extAllocated / 1024, extLimit / 1024,
markSweepTime);
} else {
u4 rootTime = rootEnd - rootStart;
u4 dirtySuspendTime = dirtyStart - dirtySuspend;
u4 dirtyTime = dirtyEnd - dirtyStart;
bool isSmall = numBytesFreed > 0 && numBytesFreed < 1024;
totalTime = rootSuspendTime + rootTime + dirtySuspendTime + dirtyTime;
LOGD("%s freed %s%zdK, %d%% free %zdK/%zdK, external %zdK/%zdK, "
"paused %ums+%ums",
GcReasonStr[reason],
isSmall ? "<" : "",
numBytesFreed ? MAX(numBytesFreed / 1024, 1) : 0,
percentFree,
currAllocated / 1024, currFootprint / 1024,
extAllocated / 1024, extLimit / 1024,
rootTime, dirtyTime);
}
dvmLogGcStats(numObjectsFreed, numBytesFreed, totalTime);
if (gcHeap->ddmHpifWhen != 0) {
LOGD_HEAP("Sending VM heap info to DDM\n");
dvmDdmSendHeapInfo(gcHeap->ddmHpifWhen, false);
}
if (gcHeap->ddmHpsgWhen != 0) {
LOGD_HEAP("Dumping VM heap to DDM\n");
dvmDdmSendHeapSegments(false, false);
}
if (gcHeap->ddmNhsgWhen != 0) {
LOGD_HEAP("Dumping native heap to DDM\n");
dvmDdmSendHeapSegments(false, true);
}
}
void dvmWaitForConcurrentGcToComplete(void)
{
Thread *self = dvmThreadSelf();
ThreadStatus oldStatus;
assert(self != NULL);
oldStatus = dvmChangeStatus(self, THREAD_VMWAIT);
dvmWaitCond(&gDvm.gcHeapCond, &gDvm.gcHeapLock);
dvmChangeStatus(self, oldStatus);
}
#if WITH_HPROF
/*
* Perform garbage collection, writing heap information to the specified file.
*
* If "fd" is >= 0, the output will be written to that file descriptor.
* Otherwise, "fileName" is used to create an output file.
*
* If "fileName" is NULL, a suitable name will be generated automatically.
* (TODO: remove this when the SIGUSR1 feature goes away)
*
* If "directToDdms" is set, the other arguments are ignored, and data is
* sent directly to DDMS.
*
* Returns 0 on success, or an error code on failure.
*/
int hprofDumpHeap(const char* fileName, int fd, bool directToDdms)
{
int result;
dvmLockMutex(&gDvm.gcHeapLock);
gDvm.gcHeap->hprofDumpOnGc = true;
gDvm.gcHeap->hprofFileName = fileName;
gDvm.gcHeap->hprofFd = fd;
gDvm.gcHeap->hprofDirectToDdms = directToDdms;
dvmCollectGarbageInternal(false, GC_HPROF_DUMP_HEAP);
result = gDvm.gcHeap->hprofResult;
dvmUnlockMutex(&gDvm.gcHeapLock);
return result;
}
void dvmHeapSetHprofGcScanState(hprof_heap_tag_t state, u4 threadSerialNumber)
{
if (gDvm.gcHeap->hprofContext != NULL) {
hprofSetGcScanState(gDvm.gcHeap->hprofContext, state,
threadSerialNumber);
}
}
#endif