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8075210: Refactor strong root processing in order to allow G1 to evolve separately from GenCollectedHeap
Create a G1RootProcessor and move SharedHeap root processing to GenCollectedHeap Reviewed-by: brutisso, tschatzl, ehelin
This commit is contained in:
Mikael Gerdin
parent
68b1e61637
commit
f5292016ee
15 changed files with 645 additions and 596 deletions
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@ -32,7 +32,6 @@
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#include "runtime/atomic.inline.hpp"
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#include "runtime/fprofiler.hpp"
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#include "runtime/java.hpp"
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#include "services/management.hpp"
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#include "utilities/copy.hpp"
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#include "utilities/workgroup.hpp"
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@ -40,32 +39,12 @@ PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
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SharedHeap* SharedHeap::_sh;
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// The set of potentially parallel tasks in root scanning.
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enum SH_process_roots_tasks {
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SH_PS_Universe_oops_do,
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SH_PS_JNIHandles_oops_do,
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SH_PS_ObjectSynchronizer_oops_do,
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SH_PS_FlatProfiler_oops_do,
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SH_PS_Management_oops_do,
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SH_PS_SystemDictionary_oops_do,
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SH_PS_ClassLoaderDataGraph_oops_do,
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SH_PS_jvmti_oops_do,
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SH_PS_CodeCache_oops_do,
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// Leave this one last.
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SH_PS_NumElements
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};
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SharedHeap::SharedHeap(CollectorPolicy* policy_) :
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CollectedHeap(),
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_collector_policy(policy_),
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_strong_roots_scope(NULL),
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_strong_roots_parity(0),
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_process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
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_workers(NULL)
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{
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if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
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vm_exit_during_initialization("Failed necessary allocation.");
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}
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_sh = this; // ch is static, should be set only once.
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if (UseConcMarkSweepGC || UseG1GC) {
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_workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
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@ -79,14 +58,6 @@ SharedHeap::SharedHeap(CollectorPolicy* policy_) :
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}
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}
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int SharedHeap::n_termination() {
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return _process_strong_tasks->n_threads();
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}
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void SharedHeap::set_n_termination(int t) {
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_process_strong_tasks->set_n_threads(t);
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}
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bool SharedHeap::heap_lock_held_for_gc() {
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Thread* t = Thread::current();
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return Heap_lock->owned_by_self()
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@ -97,31 +68,6 @@ bool SharedHeap::heap_lock_held_for_gc() {
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void SharedHeap::set_par_threads(uint t) {
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assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
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_n_par_threads = t;
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_process_strong_tasks->set_n_threads(t);
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}
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#ifdef ASSERT
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class AssertNonScavengableClosure: public OopClosure {
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public:
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virtual void do_oop(oop* p) {
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assert(!Universe::heap()->is_in_partial_collection(*p),
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"Referent should not be scavengable."); }
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virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
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};
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static AssertNonScavengableClosure assert_is_non_scavengable_closure;
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#endif
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SharedHeap::StrongRootsScope* SharedHeap::active_strong_roots_scope() const {
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return _strong_roots_scope;
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}
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void SharedHeap::register_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {
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assert(_strong_roots_scope == NULL, "Should only have one StrongRootsScope active");
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assert(scope != NULL, "Illegal argument");
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_strong_roots_scope = scope;
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}
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void SharedHeap::unregister_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {
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assert(_strong_roots_scope == scope, "Wrong scope unregistered");
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_strong_roots_scope = NULL;
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}
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void SharedHeap::change_strong_roots_parity() {
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@ -135,174 +81,15 @@ void SharedHeap::change_strong_roots_parity() {
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}
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SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* heap, bool activate)
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: MarkScope(activate), _sh(heap), _n_workers_done_with_threads(0)
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: MarkScope(activate), _sh(heap)
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{
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if (_active) {
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_sh->register_strong_roots_scope(this);
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_sh->change_strong_roots_parity();
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// Zero the claimed high water mark in the StringTable
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StringTable::clear_parallel_claimed_index();
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}
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}
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SharedHeap::StrongRootsScope::~StrongRootsScope() {
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if (_active) {
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_sh->unregister_strong_roots_scope(this);
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}
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}
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Monitor* SharedHeap::StrongRootsScope::_lock = new Monitor(Mutex::leaf, "StrongRootsScope lock", false, Monitor::_safepoint_check_never);
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void SharedHeap::StrongRootsScope::mark_worker_done_with_threads(uint n_workers) {
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// The Thread work barrier is only needed by G1 Class Unloading.
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// No need to use the barrier if this is single-threaded code.
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if (UseG1GC && ClassUnloadingWithConcurrentMark && n_workers > 0) {
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uint new_value = (uint)Atomic::add(1, &_n_workers_done_with_threads);
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if (new_value == n_workers) {
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// This thread is last. Notify the others.
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MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
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_lock->notify_all();
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}
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}
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}
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void SharedHeap::StrongRootsScope::wait_until_all_workers_done_with_threads(uint n_workers) {
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assert(UseG1GC, "Currently only used by G1");
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assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
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// No need to use the barrier if this is single-threaded code.
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if (n_workers > 0 && (uint)_n_workers_done_with_threads != n_workers) {
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MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
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while ((uint)_n_workers_done_with_threads != n_workers) {
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_lock->wait(Mutex::_no_safepoint_check_flag, 0, false);
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}
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}
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}
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void SharedHeap::process_roots(bool activate_scope,
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ScanningOption so,
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OopClosure* strong_roots,
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OopClosure* weak_roots,
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CLDClosure* strong_cld_closure,
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CLDClosure* weak_cld_closure,
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CodeBlobClosure* code_roots) {
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StrongRootsScope srs(this, activate_scope);
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// General roots.
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assert(_strong_roots_parity != 0, "must have called prologue code");
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assert(code_roots != NULL, "code root closure should always be set");
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// _n_termination for _process_strong_tasks should be set up stream
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// in a method not running in a GC worker. Otherwise the GC worker
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// could be trying to change the termination condition while the task
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// is executing in another GC worker.
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// Iterating over the CLDG and the Threads are done early to allow G1 to
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// first process the strong CLDs and nmethods and then, after a barrier,
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// let the thread process the weak CLDs and nmethods.
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if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
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ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
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}
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// Some CLDs contained in the thread frames should be considered strong.
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// Don't process them if they will be processed during the ClassLoaderDataGraph phase.
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CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
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// Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
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CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
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Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p);
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// This is the point where this worker thread will not find more strong CLDs/nmethods.
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// Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
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active_strong_roots_scope()->mark_worker_done_with_threads(n_par_threads());
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if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
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Universe::oops_do(strong_roots);
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}
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// Global (strong) JNI handles
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if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
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JNIHandles::oops_do(strong_roots);
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if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
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ObjectSynchronizer::oops_do(strong_roots);
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if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
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FlatProfiler::oops_do(strong_roots);
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if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
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Management::oops_do(strong_roots);
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if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
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JvmtiExport::oops_do(strong_roots);
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if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
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SystemDictionary::roots_oops_do(strong_roots, weak_roots);
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}
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// All threads execute the following. A specific chunk of buckets
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// from the StringTable are the individual tasks.
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if (weak_roots != NULL) {
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if (CollectedHeap::use_parallel_gc_threads()) {
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StringTable::possibly_parallel_oops_do(weak_roots);
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} else {
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StringTable::oops_do(weak_roots);
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}
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}
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if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
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if (so & SO_ScavengeCodeCache) {
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assert(code_roots != NULL, "must supply closure for code cache");
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// We only visit parts of the CodeCache when scavenging.
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CodeCache::scavenge_root_nmethods_do(code_roots);
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}
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if (so & SO_AllCodeCache) {
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assert(code_roots != NULL, "must supply closure for code cache");
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// CMSCollector uses this to do intermediate-strength collections.
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// We scan the entire code cache, since CodeCache::do_unloading is not called.
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CodeCache::blobs_do(code_roots);
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}
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// Verify that the code cache contents are not subject to
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// movement by a scavenging collection.
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DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
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DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
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}
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_process_strong_tasks->all_tasks_completed();
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}
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void SharedHeap::process_all_roots(bool activate_scope,
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ScanningOption so,
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OopClosure* roots,
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CLDClosure* cld_closure,
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CodeBlobClosure* code_closure) {
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process_roots(activate_scope, so,
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roots, roots,
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cld_closure, cld_closure,
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code_closure);
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}
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void SharedHeap::process_strong_roots(bool activate_scope,
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ScanningOption so,
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OopClosure* roots,
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CLDClosure* cld_closure,
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CodeBlobClosure* code_closure) {
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process_roots(activate_scope, so,
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roots, NULL,
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cld_closure, NULL,
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code_closure);
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}
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class AlwaysTrueClosure: public BoolObjectClosure {
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public:
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bool do_object_b(oop p) { return true; }
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};
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static AlwaysTrueClosure always_true;
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void SharedHeap::process_weak_roots(OopClosure* root_closure) {
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// Global (weak) JNI handles
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JNIHandles::weak_oops_do(&always_true, root_closure);
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}
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void SharedHeap::set_barrier_set(BarrierSet* bs) {
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_barrier_set = bs;
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// Cached barrier set for fast access in oops
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