sharedHeap.cpp revision 3008
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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#include "precompiled.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "code/codeCache.hpp"
#include "gc_interface/collectedHeap.inline.hpp"
#include "memory/sharedHeap.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/fprofiler.hpp"
#include "runtime/java.hpp"
#include "services/management.hpp"
#include "utilities/copy.hpp"
#include "utilities/workgroup.hpp"
SharedHeap* SharedHeap::_sh;
// The set of potentially parallel tasks in strong root scanning.
enum SH_process_strong_roots_tasks {
SH_PS_Universe_oops_do,
SH_PS_JNIHandles_oops_do,
SH_PS_ObjectSynchronizer_oops_do,
SH_PS_FlatProfiler_oops_do,
SH_PS_Management_oops_do,
SH_PS_SystemDictionary_oops_do,
SH_PS_jvmti_oops_do,
SH_PS_StringTable_oops_do,
SH_PS_CodeCache_oops_do,
// Leave this one last.
SH_PS_NumElements
};
SharedHeap::SharedHeap(CollectorPolicy* policy_) :
CollectedHeap(),
_collector_policy(policy_),
_perm_gen(NULL), _rem_set(NULL),
_strong_roots_parity(0),
_process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
_workers(NULL)
{
if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
vm_exit_during_initialization("Failed necessary allocation.");
}
_sh = this; // ch is static, should be set only once.
if ((UseParNewGC ||
(UseConcMarkSweepGC && CMSParallelRemarkEnabled) ||
UseG1GC) &&
ParallelGCThreads > 0) {
_workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
/* are_GC_task_threads */true,
/* are_ConcurrentGC_threads */false);
if (_workers == NULL) {
vm_exit_during_initialization("Failed necessary allocation.");
} else {
_workers->initialize_workers();
}
}
}
int SharedHeap::n_termination() {
return _process_strong_tasks->n_threads();
}
void SharedHeap::set_n_termination(int t) {
_process_strong_tasks->set_n_threads(t);
}
bool SharedHeap::heap_lock_held_for_gc() {
Thread* t = Thread::current();
return Heap_lock->owned_by_self()
|| ( (t->is_GC_task_thread() || t->is_VM_thread())
&& _thread_holds_heap_lock_for_gc);
}
void SharedHeap::set_par_threads(uint t) {
assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
_n_par_threads = t;
_process_strong_tasks->set_n_threads(t);
}
class AssertIsPermClosure: public OopClosure {
public:
virtual void do_oop(oop* p) {
assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
}
virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
};
static AssertIsPermClosure assert_is_perm_closure;
#ifdef ASSERT
class AssertNonScavengableClosure: public OopClosure {
public:
virtual void do_oop(oop* p) {
assert(!Universe::heap()->is_in_partial_collection(*p),
"Referent should not be scavengable."); }
virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
};
static AssertNonScavengableClosure assert_is_non_scavengable_closure;
#endif
void SharedHeap::change_strong_roots_parity() {
// Also set the new collection parity.
assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
"Not in range.");
_strong_roots_parity++;
if (_strong_roots_parity == 3) _strong_roots_parity = 1;
assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
"Not in range.");
}
SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
: MarkScope(activate)
{
if (_active) {
outer->change_strong_roots_parity();
}
}
SharedHeap::StrongRootsScope::~StrongRootsScope() {
// nothing particular
}
void SharedHeap::process_strong_roots(bool activate_scope,
bool collecting_perm_gen,
ScanningOption so,
OopClosure* roots,
CodeBlobClosure* code_roots,
OopsInGenClosure* perm_blk) {
StrongRootsScope srs(this, activate_scope);
// General strong roots.
assert(_strong_roots_parity != 0, "must have called prologue code");
// _n_termination for _process_strong_tasks should be set up stream
// in a method not running in a GC worker. Otherwise the GC worker
// could be trying to change the termination condition while the task
// is executing in another GC worker.
if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
Universe::oops_do(roots);
// Consider perm-gen discovered lists to be strong.
perm_gen()->ref_processor()->weak_oops_do(roots);
}
// Global (strong) JNI handles
if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
JNIHandles::oops_do(roots);
// All threads execute this; the individual threads are task groups.
if (ParallelGCThreads > 0) {
Threads::possibly_parallel_oops_do(roots, code_roots);
} else {
Threads::oops_do(roots, code_roots);
}
if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
ObjectSynchronizer::oops_do(roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
FlatProfiler::oops_do(roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
Management::oops_do(roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
JvmtiExport::oops_do(roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
if (so & SO_AllClasses) {
SystemDictionary::oops_do(roots);
} else if (so & SO_SystemClasses) {
SystemDictionary::always_strong_oops_do(roots);
}
}
if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
if (so & SO_Strings || (!collecting_perm_gen && !JavaObjectsInPerm)) {
StringTable::oops_do(roots);
}
if (JavaObjectsInPerm) {
// Verify the string table contents are in the perm gen
NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
}
}
if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
if (so & SO_CodeCache) {
// (Currently, CMSCollector uses this to do intermediate-strength collections.)
assert(collecting_perm_gen, "scanning all of code cache");
assert(code_roots != NULL, "must supply closure for code cache");
if (code_roots != NULL) {
CodeCache::blobs_do(code_roots);
}
} else if (so & (SO_SystemClasses|SO_AllClasses)) {
if (!collecting_perm_gen) {
// If we are collecting from class statics, but we are not going to
// visit all of the CodeCache, collect from the non-perm roots if any.
// This makes the code cache function temporarily as a source of strong
// roots for oops, until the next major collection.
//
// If collecting_perm_gen is true, we require that this phase will call
// CodeCache::do_unloading. This will kill off nmethods with expired
// weak references, such as stale invokedynamic targets.
CodeCache::scavenge_root_nmethods_do(code_roots);
}
}
// Verify that the code cache contents are not subject to
// movement by a scavenging collection.
DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
}
if (!collecting_perm_gen) {
// All threads perform this; coordination is handled internally.
rem_set()->younger_refs_iterate(perm_gen(), perm_blk);
}
_process_strong_tasks->all_tasks_completed();
}
class AlwaysTrueClosure: public BoolObjectClosure {
public:
void do_object(oop p) { ShouldNotReachHere(); }
bool do_object_b(oop p) { return true; }
};
static AlwaysTrueClosure always_true;
class SkipAdjustingSharedStrings: public OopClosure {
OopClosure* _clo;
public:
SkipAdjustingSharedStrings(OopClosure* clo) : _clo(clo) {}
virtual void do_oop(oop* p) {
oop o = (*p);
if (!o->is_shared_readwrite()) {
_clo->do_oop(p);
}
}
virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
};
// Unmarked shared Strings in the StringTable (which got there due to
// being in the constant pools of as-yet unloaded shared classes) were
// not marked and therefore did not have their mark words preserved.
// These entries are also deliberately not purged from the string
// table during unloading of unmarked strings. If an identity hash
// code was computed for any of these objects, it will not have been
// cleared to zero during the forwarding process or by the
// RecursiveAdjustSharedObjectClosure, and will be confused by the
// adjusting process as a forwarding pointer. We need to skip
// forwarding StringTable entries which contain unmarked shared
// Strings. Actually, since shared strings won't be moving, we can
// just skip adjusting any shared entries in the string table.
void SharedHeap::process_weak_roots(OopClosure* root_closure,
CodeBlobClosure* code_roots,
OopClosure* non_root_closure) {
// Global (weak) JNI handles
JNIHandles::weak_oops_do(&always_true, root_closure);
CodeCache::blobs_do(code_roots);
if (UseSharedSpaces && !DumpSharedSpaces) {
SkipAdjustingSharedStrings skip_closure(root_closure);
StringTable::oops_do(&skip_closure);
} else {
StringTable::oops_do(root_closure);
}
}
void SharedHeap::set_barrier_set(BarrierSet* bs) {
_barrier_set = bs;
// Cached barrier set for fast access in oops
oopDesc::set_bs(bs);
}
void SharedHeap::post_initialize() {
ref_processing_init();
}
void SharedHeap::ref_processing_init() {
perm_gen()->ref_processor_init();
}
// Some utilities.
void SharedHeap::print_size_transition(outputStream* out,
size_t bytes_before,
size_t bytes_after,
size_t capacity) {
out->print(" %d%s->%d%s(%d%s)",
byte_size_in_proper_unit(bytes_before),
proper_unit_for_byte_size(bytes_before),
byte_size_in_proper_unit(bytes_after),
proper_unit_for_byte_size(bytes_after),
byte_size_in_proper_unit(capacity),
proper_unit_for_byte_size(capacity));
}