sharedHeap.cpp revision 113
/*
* Copyright 2000-2007 Sun Microsystems, Inc. All Rights Reserved.
* 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
# include "incls/_precompiled.incl"
# include "incls/_sharedHeap.cpp.incl"
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_vmSymbols_oops_do,
SH_PS_SymbolTable_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), _n_par_threads(0)
{
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)) &&
ParallelGCThreads > 0) {
_workers = new WorkGang("Parallel GC Threads", ParallelGCThreads, true);
if (_workers == NULL) {
vm_exit_during_initialization("Failed necessary allocation.");
}
}
}
void SharedHeap::set_par_threads(int t) {
_n_par_threads = t;
_process_strong_tasks->set_par_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;
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.");
}
void SharedHeap::process_strong_roots(bool collecting_perm_gen,
ScanningOption so,
OopClosure* roots,
OopsInGenClosure* perm_blk) {
// General strong roots.
if (n_par_threads() == 0) change_strong_roots_parity();
if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
Universe::oops_do(roots);
ReferenceProcessor::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);
} else {
Threads::oops_do(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_SymbolTable_oops_do)) {
if (so & SO_Symbols) {
SymbolTable::oops_do(roots);
}
// Verify if the symbol table contents are in the perm gen
NOT_PRODUCT(SymbolTable::oops_do(&assert_is_perm_closure));
}
if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
if (so & SO_Strings) {
StringTable::oops_do(roots);
}
// Verify if 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) {
CodeCache::oops_do(roots);
}
// Verify if the code cache contents are in the perm gen
NOT_PRODUCT(CodeCache::oops_do(&assert_is_perm_closure));
}
// Roots that should point only into permanent generation.
{
OopClosure* blk = NULL;
if (collecting_perm_gen) {
blk = roots;
} else {
debug_only(blk = &assert_is_perm_closure);
}
if (blk != NULL) {
if (!_process_strong_tasks->is_task_claimed(SH_PS_vmSymbols_oops_do))
vmSymbols::oops_do(blk);
}
}
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,
OopClosure* non_root_closure) {
// Global (weak) JNI handles
JNIHandles::weak_oops_do(&always_true, root_closure);
CodeCache::oops_do(non_root_closure);
SymbolTable::oops_do(root_closure);
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();
}
void SharedHeap::fill_region_with_object(MemRegion mr) {
// Disable the posting of JVMTI VMObjectAlloc events as we
// don't want the filling of tlabs with filler arrays to be
// reported to the profiler.
NoJvmtiVMObjectAllocMark njm;
// Disable low memory detector because there is no real allocation.
LowMemoryDetectorDisabler lmd_dis;
// It turns out that post_allocation_setup_array takes a handle, so the
// call below contains an implicit conversion. Best to free that handle
// as soon as possible.
HandleMark hm;
size_t word_size = mr.word_size();
size_t aligned_array_header_size =
align_object_size(typeArrayOopDesc::header_size(T_INT));
if (word_size >= aligned_array_header_size) {
const size_t array_length =
pointer_delta(mr.end(), mr.start()) -
typeArrayOopDesc::header_size(T_INT);
const size_t array_length_words =
array_length * (HeapWordSize/sizeof(jint));
post_allocation_setup_array(Universe::intArrayKlassObj(),
mr.start(),
mr.word_size(),
(int)array_length_words);
#ifdef ASSERT
HeapWord* elt_words = (mr.start() + typeArrayOopDesc::header_size(T_INT));
Copy::fill_to_words(elt_words, array_length, 0xDEAFBABE);
#endif
} else {
assert(word_size == (size_t)oopDesc::header_size(), "Unaligned?");
post_allocation_setup_obj(SystemDictionary::object_klass(),
mr.start(),
mr.word_size());
}
}
// Some utilities.
void SharedHeap::print_size_transition(size_t bytes_before,
size_t bytes_after,
size_t capacity) {
tty->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));
}