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* Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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#include "precompiled.hpp"
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#include "classfile/classLoaderDataGraph.inline.hpp"
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#include "classfile/javaClasses.hpp"
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#include "classfile/protectionDomainCache.hpp"
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#include "classfile/stringTable.hpp"
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#include "classfile/symbolTable.hpp"
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#include "classfile/systemDictionary.hpp"
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#include "classfile/vmClasses.hpp"
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#include "gc/shared/oopStorage.hpp"
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#include "gc/shared/oopStorageSet.hpp"
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#include "memory/universe.hpp"
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#include "interpreter/oopMapCache.hpp"
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#include "oops/oopHandle.inline.hpp"
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#include "runtime/handles.inline.hpp"
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#include "runtime/interfaceSupport.inline.hpp"
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#include "runtime/java.hpp"
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#include "runtime/javaCalls.hpp"
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#include "runtime/jniHandles.hpp"
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#include "runtime/serviceThread.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "runtime/os.hpp"
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#include "prims/jvmtiImpl.hpp"
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#include "prims/jvmtiTagMap.hpp"
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#include "prims/resolvedMethodTable.hpp"
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#include "services/diagnosticArgument.hpp"
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#include "services/diagnosticFramework.hpp"
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#include "services/finalizerService.hpp"
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#include "services/gcNotifier.hpp"
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#include "services/lowMemoryDetector.hpp"
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#include "services/threadIdTable.hpp"
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DEBUG_ONLY(JavaThread* ServiceThread::_instance = nullptr;)
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JvmtiDeferredEvent* ServiceThread::_jvmti_event = nullptr;
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// The service thread has it's own static deferred event queue.
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// Events can be posted before JVMTI vm_start, so it's too early to call JvmtiThreadState::state_for
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// to add this field to the per-JavaThread event queue. TODO: fix this sometime later
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JvmtiDeferredEventQueue ServiceThread::_jvmti_service_queue;
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void ServiceThread::initialize() {66
const char* name = "Service Thread";
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Handle thread_oop = JavaThread::create_system_thread_object(name, CHECK);
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ServiceThread* thread = new ServiceThread(&service_thread_entry);
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JavaThread::vm_exit_on_osthread_failure(thread);
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JavaThread::start_internal_daemon(THREAD, thread, thread_oop, NearMaxPriority);
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DEBUG_ONLY(_instance = thread;)
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static void cleanup_oopstorages() {77
for (OopStorage* storage : OopStorageSet::Range<OopStorageSet::Id>()) {78
storage->delete_empty_blocks();
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void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {84
bool sensors_changed = false;
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bool has_jvmti_events = false;
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bool has_gc_notification_event = false;
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bool has_dcmd_notification_event = false;
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bool stringtable_work = false;
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bool symboltable_work = false;
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bool finalizerservice_work = false;
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bool resolved_method_table_work = false;
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bool thread_id_table_work = false;
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bool protection_domain_table_work = false;
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bool oopstorage_work = false;
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JvmtiDeferredEvent jvmti_event;
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bool oop_handles_to_release = false;
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bool cldg_cleanup_work = false;
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bool jvmti_tagmap_work = false;
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bool oopmap_cache_work = false;
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// Need state transition ThreadBlockInVM so that this thread
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// will be handled by safepoint correctly when this thread is
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// notified at a safepoint.
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// This ThreadBlockInVM object is not also considered to be
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// suspend-equivalent because ServiceThread is not visible to
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// external suspension.
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ThreadBlockInVM tbivm(jt);
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MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
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// Process all available work on each (outer) iteration, rather than
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// only the first recognized bit of work, to avoid frequently true early
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// tests from potentially starving later work. Hence the use of
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// arithmetic-or to combine results; we don't want short-circuiting.
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while (((sensors_changed = (!UseNotificationThread && LowMemoryDetector::has_pending_requests())) |
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(has_jvmti_events = _jvmti_service_queue.has_events()) |
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(has_gc_notification_event = (!UseNotificationThread && GCNotifier::has_event())) |
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(has_dcmd_notification_event = (!UseNotificationThread && DCmdFactory::has_pending_jmx_notification())) |
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(stringtable_work = StringTable::has_work()) |
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(symboltable_work = SymbolTable::has_work()) |
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(finalizerservice_work = FinalizerService::has_work()) |
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(resolved_method_table_work = ResolvedMethodTable::has_work()) |
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(thread_id_table_work = ThreadIdTable::has_work()) |
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(protection_domain_table_work = ProtectionDomainCacheTable::has_work()) |
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(oopstorage_work = OopStorage::has_cleanup_work_and_reset()) |
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(oop_handles_to_release = JavaThread::has_oop_handles_to_release()) |
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(cldg_cleanup_work = ClassLoaderDataGraph::should_clean_metaspaces_and_reset()) |
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(jvmti_tagmap_work = JvmtiTagMap::has_object_free_events_and_reset()) |
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(oopmap_cache_work = OopMapCache::has_cleanup_work())
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// Wait until notified that there is some work to do or timer expires.
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// Some cleanup requests don't notify the ServiceThread so work needs to be done at periodic intervals.
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ml.wait(ServiceThreadCleanupInterval);
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if (has_jvmti_events) {138
// Get the event under the Service_lock
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jvmti_event = _jvmti_service_queue.dequeue();
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_jvmti_event = &jvmti_event;
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if (stringtable_work) {145
StringTable::do_concurrent_work(jt);
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if (symboltable_work) {149
SymbolTable::do_concurrent_work(jt);
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if (finalizerservice_work) {153
FinalizerService::do_concurrent_work(jt);
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if (has_jvmti_events) {157
_jvmti_event->post();
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_jvmti_event = nullptr; // reset
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if (!UseNotificationThread) {162
if (sensors_changed) {163
LowMemoryDetector::process_sensor_changes(jt);
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if(has_gc_notification_event) {167
GCNotifier::sendNotification(CHECK);
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if(has_dcmd_notification_event) {171
DCmdFactory::send_notification(CHECK);
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if (resolved_method_table_work) {176
ResolvedMethodTable::do_concurrent_work(jt);
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if (thread_id_table_work) {180
ThreadIdTable::do_concurrent_work(jt);
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if (protection_domain_table_work) {184
ProtectionDomainCacheTable::unlink();
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if (oopstorage_work) {188
cleanup_oopstorages();
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if (oop_handles_to_release) {192
JavaThread::release_oop_handles();
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if (cldg_cleanup_work) {196
ClassLoaderDataGraph::safepoint_and_clean_metaspaces();
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if (jvmti_tagmap_work) {200
JvmtiTagMap::flush_all_object_free_events();
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if (oopmap_cache_work) {204
OopMapCache::cleanup();
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void ServiceThread::enqueue_deferred_event(JvmtiDeferredEvent* event) {210
MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
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// If you enqueue events before the service thread runs, gc
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// cannot keep the nmethod alive. This could be restricted to compiled method
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// load and unload events, if we wanted to be picky.
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assert(_instance != nullptr, "cannot enqueue events before the service thread runs");
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_jvmti_service_queue.enqueue(*event);
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Service_lock->notify_all();
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void ServiceThread::oops_do_no_frames(OopClosure* f, NMethodClosure* cf) {220
JavaThread::oops_do_no_frames(f, cf);
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// The ServiceThread "owns" the JVMTI Deferred events, scan them here
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// to keep them alive until they are processed.
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if (_jvmti_event != nullptr) {224
_jvmti_event->oops_do(f, cf);
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// Requires a lock, because threads can be adding to this queue.
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MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
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_jvmti_service_queue.oops_do(f, cf);
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void ServiceThread::nmethods_do(NMethodClosure* cf) {232
JavaThread::nmethods_do(cf);
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if (_jvmti_event != nullptr) {235
_jvmti_event->nmethods_do(cf);
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// Requires a lock, because threads can be adding to this queue.
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MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
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_jvmti_service_queue.nmethods_do(cf);