src/share/vm/memory/sharedHeap.cpp
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@@ -27,22 +27,23 @@
#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/atomic.inline.hpp"
#include "runtime/fprofiler.hpp"
#include "runtime/java.hpp"
#include "services/management.hpp"
#include "utilities/copy.hpp"
#include "utilities/workgroup.hpp"
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,
SH_PS_FlatProfiler_oops_do,
SH_PS_Management_oops_do,
@@ -56,10 +57,11 @@
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)
{
if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
@@ -112,126 +114,188 @@
virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
};
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,
"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)
+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,
+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* roots,
- KlassClosure* klass_closure) {
+ 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.
- if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
- Universe::oops_do(roots);
+
+ // 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);
}
- // 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);
+ // 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;
- 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);
+ 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(strong_roots);
}
+ // Global (strong) JNI handles
+ if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
+ 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; }
};
static AlwaysTrueClosure always_true;