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8049421: G1 Class Unloading after completing a concurrent mark cycle

Browse source 
Co-authored-by: Mikael Gerdin <mikael.gerdin@oracle.com>
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
This commit is contained in:
Stefan Karlsson 2014-07-07 10:12:40 +02:00
parent ef1e9b3c80
commit 1b001a2afd
75 changed files with 2169 additions and 874 deletions
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170
hotspot/src/share/vm/memory/sharedHeap.cpp
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@ -29,6 +29,7 @@
#include "gc_interface/collectedHeap.inline.hpp"
#include "memory/sharedHeap.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/atomic.inline.hpp"
#include "runtime/fprofiler.hpp"
#include "runtime/java.hpp"
#include "services/management.hpp"
@ -39,8 +40,8 @@ PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
SharedHeap* SharedHeap::_sh;
// The set of potentially parallel tasks in strong root scanning.
enum SH_process_strong_roots_tasks {
// The set of potentially parallel tasks in root scanning.
enum SH_process_roots_tasks {
SH_PS_Universe_oops_do,
SH_PS_JNIHandles_oops_do,
SH_PS_ObjectSynchronizer_oops_do,
@ -58,6 +59,7 @@ SharedHeap::SharedHeap(CollectorPolicy* policy_) :
CollectedHeap(),
_collector_policy(policy_),
_rem_set(NULL),
_strong_roots_scope(NULL),
_strong_roots_parity(0),
_process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
_workers(NULL)
@ -114,6 +116,19 @@ public:
static AssertNonScavengableClosure assert_is_non_scavengable_closure;
#endif
SharedHeap::StrongRootsScope* SharedHeap::active_strong_roots_scope() const {
return _strong_roots_scope;
}
void SharedHeap::register_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {
assert(_strong_roots_scope == NULL, "Should only have one StrongRootsScope active");
assert(scope != NULL, "Illegal argument");
_strong_roots_scope = scope;
}
void SharedHeap::unregister_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {
assert(_strong_roots_scope == scope, "Wrong scope unregistered");
_strong_roots_scope = NULL;
}
void SharedHeap::change_strong_roots_parity() {
// Also set the new collection parity.
assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
@ -124,112 +139,161 @@ void SharedHeap::change_strong_roots_parity() {
"Not in range.");
}
SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
: MarkScope(activate)
SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* heap, bool activate)
: MarkScope(activate), _sh(heap), _n_workers_done_with_threads(0)
{
if (_active) {
outer->change_strong_roots_parity();
_sh->register_strong_roots_scope(this);
_sh->change_strong_roots_parity();
// Zero the claimed high water mark in the StringTable
StringTable::clear_parallel_claimed_index();
}
}
SharedHeap::StrongRootsScope::~StrongRootsScope() {
// nothing particular
if (_active) {
_sh->unregister_strong_roots_scope(this);
}
}
void SharedHeap::process_strong_roots(bool activate_scope,
ScanningOption so,
OopClosure* roots,
KlassClosure* klass_closure) {
Monitor* SharedHeap::StrongRootsScope::_lock = new Monitor(Mutex::leaf, "StrongRootsScope lock", false);
void SharedHeap::StrongRootsScope::mark_worker_done_with_threads(uint n_workers) {
// The Thread work barrier is only needed by G1.
// No need to use the barrier if this is single-threaded code.
if (UseG1GC && n_workers > 0) {
uint new_value = (uint)Atomic::add(1, &_n_workers_done_with_threads);
if (new_value == n_workers) {
// This thread is last. Notify the others.
MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
_lock->notify_all();
}
}
}
void SharedHeap::StrongRootsScope::wait_until_all_workers_done_with_threads(uint n_workers) {
// No need to use the barrier if this is single-threaded code.
if (n_workers > 0 && (uint)_n_workers_done_with_threads != n_workers) {
MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
while ((uint)_n_workers_done_with_threads != n_workers) {
_lock->wait(Mutex::_no_safepoint_check_flag, 0, false);
}
}
}
void SharedHeap::process_roots(bool activate_scope,
ScanningOption so,
OopClosure* strong_roots,
OopClosure* weak_roots,
CLDClosure* strong_cld_closure,
CLDClosure* weak_cld_closure,
CodeBlobClosure* code_roots) {
StrongRootsScope srs(this, activate_scope);
// General strong roots.
// General roots.
assert(_strong_roots_parity != 0, "must have called prologue code");
assert(code_roots != NULL, "code root closure should always be set");
// _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.
// Iterating over the CLDG and the Threads are done early to allow G1 to
// first process the strong CLDs and nmethods and then, after a barrier,
// let the thread process the weak CLDs and nmethods.
if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
}
// Some CLDs contained in the thread frames should be considered strong.
// Don't process them if they will be processed during the ClassLoaderDataGraph phase.
CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
// Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p);
// This is the point where this worker thread will not find more strong CLDs/nmethods.
// Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
active_strong_roots_scope()->mark_worker_done_with_threads(n_par_threads());
if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
Universe::oops_do(roots);
Universe::oops_do(strong_roots);
}
// Global (strong) JNI handles
if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
JNIHandles::oops_do(roots);
CodeBlobToOopClosure code_roots(roots, true);
CLDToOopClosure roots_from_clds(roots);
// If we limit class scanning to SO_SystemClasses we need to apply a CLD closure to
// CLDs which are strongly reachable from the thread stacks.
CLDToOopClosure* roots_from_clds_p = ((so & SO_SystemClasses) ? &roots_from_clds : NULL);
// All threads execute this; the individual threads are task groups.
if (CollectedHeap::use_parallel_gc_threads()) {
Threads::possibly_parallel_oops_do(roots, roots_from_clds_p, &code_roots);
} else {
Threads::oops_do(roots, roots_from_clds_p, &code_roots);
}
JNIHandles::oops_do(strong_roots);
if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
ObjectSynchronizer::oops_do(roots);
ObjectSynchronizer::oops_do(strong_roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
FlatProfiler::oops_do(roots);
FlatProfiler::oops_do(strong_roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
Management::oops_do(roots);
Management::oops_do(strong_roots);
if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
JvmtiExport::oops_do(roots);
JvmtiExport::oops_do(strong_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);
} else {
fatal("We should always have selected either SO_AllClasses or SO_SystemClasses");
}
}
if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
if (so & SO_AllClasses) {
ClassLoaderDataGraph::oops_do(roots, klass_closure, /* must_claim */ false);
} else if (so & SO_SystemClasses) {
ClassLoaderDataGraph::always_strong_oops_do(roots, klass_closure, /* must_claim */ true);
}
SystemDictionary::roots_oops_do(strong_roots, weak_roots);
}
// All threads execute the following. A specific chunk of buckets
// from the StringTable are the individual tasks.
if (so & SO_Strings) {
if (weak_roots != NULL) {
if (CollectedHeap::use_parallel_gc_threads()) {
StringTable::possibly_parallel_oops_do(roots);
StringTable::possibly_parallel_oops_do(weak_roots);
} else {
StringTable::oops_do(roots);
StringTable::oops_do(weak_roots);
}
}
if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
if (so & SO_ScavengeCodeCache) {
assert(&code_roots != NULL, "must supply closure for code cache");
assert(code_roots != NULL, "must supply closure for code cache");
// We only visit parts of the CodeCache when scavenging.
CodeCache::scavenge_root_nmethods_do(&code_roots);
CodeCache::scavenge_root_nmethods_do(code_roots);
}
if (so & SO_AllCodeCache) {
assert(&code_roots != NULL, "must supply closure for code cache");
assert(code_roots != NULL, "must supply closure for code cache");
// CMSCollector uses this to do intermediate-strength collections.
// We scan the entire code cache, since CodeCache::do_unloading is not called.
CodeCache::blobs_do(&code_roots);
CodeCache::blobs_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(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
}
_process_strong_tasks->all_tasks_completed();
}
void SharedHeap::process_all_roots(bool activate_scope,
ScanningOption so,
OopClosure* roots,
CLDClosure* cld_closure,
CodeBlobClosure* code_closure) {
process_roots(activate_scope, so,
roots, roots,
cld_closure, cld_closure,
code_closure);
}
void SharedHeap::process_strong_roots(bool activate_scope,
ScanningOption so,
OopClosure* roots,
CLDClosure* cld_closure,
CodeBlobClosure* code_closure) {
process_roots(activate_scope, so,
roots, NULL,
cld_closure, NULL,
code_closure);
}
class AlwaysTrueClosure: public BoolObjectClosure {
public:
bool do_object_b(oop p) { return true; }