/* * Copyright (c) 2003, 2017, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #ifndef SHARE_VM_SERVICES_THREADSERVICE_HPP #define SHARE_VM_SERVICES_THREADSERVICE_HPP #include "classfile/javaClasses.hpp" #include "runtime/handles.hpp" #include "runtime/init.hpp" #include "runtime/jniHandles.hpp" #include "runtime/objectMonitor.hpp" #include "runtime/objectMonitor.inline.hpp" #include "runtime/perfData.hpp" #include "runtime/thread.hpp" #include "services/management.hpp" #include "services/serviceUtil.hpp" class OopClosure; class ThreadDumpResult; class ThreadStackTrace; class ThreadSnapshot; class StackFrameInfo; class ThreadConcurrentLocks; class DeadlockCycle; // VM monitoring and management support for the thread and // synchronization subsystem // // Thread contention monitoring is disabled by default. // When enabled, the VM will begin measuring the accumulated // elapsed time a thread blocked on synchronization. // class ThreadService : public AllStatic { private: // These counters could be moved to Threads class static PerfCounter* _total_threads_count; static PerfVariable* _live_threads_count; static PerfVariable* _peak_threads_count; static PerfVariable* _daemon_threads_count; // These 2 counters are atomically incremented once the thread is exiting. // They will be atomically decremented when ThreadService::remove_thread is called. static volatile int _exiting_threads_count; static volatile int _exiting_daemon_threads_count; static bool _thread_monitoring_contention_enabled; static bool _thread_cpu_time_enabled; static bool _thread_allocated_memory_enabled; // Need to keep the list of thread dump result that // keep references to Method* since thread dump can be // requested by multiple threads concurrently. static ThreadDumpResult* _threaddump_list; public: static void init(); static void add_thread(JavaThread* thread, bool daemon); static void remove_thread(JavaThread* thread, bool daemon); static void current_thread_exiting(JavaThread* jt); static bool set_thread_monitoring_contention(bool flag); static bool is_thread_monitoring_contention() { return _thread_monitoring_contention_enabled; } static bool set_thread_cpu_time_enabled(bool flag); static bool is_thread_cpu_time_enabled() { return _thread_cpu_time_enabled; } static bool set_thread_allocated_memory_enabled(bool flag); static bool is_thread_allocated_memory_enabled() { return _thread_cpu_time_enabled; } static jlong get_total_thread_count() { return _total_threads_count->get_value(); } static jlong get_peak_thread_count() { return _peak_threads_count->get_value(); } static jlong get_live_thread_count() { return _live_threads_count->get_value() - _exiting_threads_count; } static jlong get_daemon_thread_count() { return _daemon_threads_count->get_value() - _exiting_daemon_threads_count; } static int exiting_threads_count() { return _exiting_threads_count; } static int exiting_daemon_threads_count() { return _exiting_daemon_threads_count; } // Support for thread dump static void add_thread_dump(ThreadDumpResult* dump); static void remove_thread_dump(ThreadDumpResult* dump); static Handle get_current_contended_monitor(JavaThread* thread); // This function is called by JVM_DumpThreads. static Handle dump_stack_traces(GrowableArray* threads, int num_threads, TRAPS); static void reset_peak_thread_count(); static void reset_contention_count_stat(JavaThread* thread); static void reset_contention_time_stat(JavaThread* thread); static DeadlockCycle* find_deadlocks_at_safepoint(ThreadsList * t_list, bool object_monitors_only); // GC support static void oops_do(OopClosure* f); static void metadata_do(void f(Metadata*)); }; // Per-thread Statistics for synchronization class ThreadStatistics : public CHeapObj { private: // The following contention statistics are only updated by // the thread owning these statistics when contention occurs. jlong _contended_enter_count; elapsedTimer _contended_enter_timer; jlong _monitor_wait_count; elapsedTimer _monitor_wait_timer; jlong _sleep_count; elapsedTimer _sleep_timer; // These two reset flags are set to true when another thread // requests to reset the statistics. The actual statistics // are reset when the thread contention occurs and attempts // to update the statistics. bool _count_pending_reset; bool _timer_pending_reset; // Keep accurate times for potentially recursive class operations int _perf_recursion_counts[6]; elapsedTimer _perf_timers[6]; // utility functions void check_and_reset_count() { if (!_count_pending_reset) return; _contended_enter_count = 0; _monitor_wait_count = 0; _sleep_count = 0; _count_pending_reset = 0; } void check_and_reset_timer() { if (!_timer_pending_reset) return; _contended_enter_timer.reset(); _monitor_wait_timer.reset(); _sleep_timer.reset(); _timer_pending_reset = 0; } public: ThreadStatistics(); jlong contended_enter_count() { return (_count_pending_reset ? 0 : _contended_enter_count); } jlong contended_enter_ticks() { return (_timer_pending_reset ? 0 : _contended_enter_timer.active_ticks()); } jlong monitor_wait_count() { return (_count_pending_reset ? 0 : _monitor_wait_count); } jlong monitor_wait_ticks() { return (_timer_pending_reset ? 0 : _monitor_wait_timer.active_ticks()); } jlong sleep_count() { return (_count_pending_reset ? 0 : _sleep_count); } jlong sleep_ticks() { return (_timer_pending_reset ? 0 : _sleep_timer.active_ticks()); } void monitor_wait() { check_and_reset_count(); _monitor_wait_count++; } void monitor_wait_begin() { check_and_reset_timer(); _monitor_wait_timer.start(); } void monitor_wait_end() { _monitor_wait_timer.stop(); check_and_reset_timer(); } void thread_sleep() { check_and_reset_count(); _sleep_count++; } void thread_sleep_begin() { check_and_reset_timer(); _sleep_timer.start(); } void thread_sleep_end() { _sleep_timer.stop(); check_and_reset_timer(); } void contended_enter() { check_and_reset_count(); _contended_enter_count++; } void contended_enter_begin() { check_and_reset_timer(); _contended_enter_timer.start(); } void contended_enter_end() { _contended_enter_timer.stop(); check_and_reset_timer(); } void reset_count_stat() { _count_pending_reset = true; } void reset_time_stat() { _timer_pending_reset = true; } int* perf_recursion_counts_addr() { return _perf_recursion_counts; } elapsedTimer* perf_timers_addr() { return _perf_timers; } }; // Thread snapshot to represent the thread state and statistics class ThreadSnapshot : public CHeapObj { private: // This JavaThread* is protected by being stored in objects that are // protected by a ThreadsListSetter (ThreadDumpResult). JavaThread* _thread; oop _threadObj; java_lang_Thread::ThreadStatus _thread_status; bool _is_ext_suspended; bool _is_in_native; jlong _contended_enter_ticks; jlong _contended_enter_count; jlong _monitor_wait_ticks; jlong _monitor_wait_count; jlong _sleep_ticks; jlong _sleep_count; oop _blocker_object; oop _blocker_object_owner; ThreadStackTrace* _stack_trace; ThreadConcurrentLocks* _concurrent_locks; ThreadSnapshot* _next; public: // Dummy snapshot ThreadSnapshot() : _thread(NULL), _threadObj(NULL), _stack_trace(NULL), _concurrent_locks(NULL), _next(NULL), _blocker_object(NULL), _blocker_object_owner(NULL) {}; ThreadSnapshot(ThreadsList * t_list, JavaThread* thread); ~ThreadSnapshot(); java_lang_Thread::ThreadStatus thread_status() { return _thread_status; } oop threadObj() const { return _threadObj; } void set_next(ThreadSnapshot* n) { _next = n; } bool is_ext_suspended() { return _is_ext_suspended; } bool is_in_native() { return _is_in_native; } jlong contended_enter_count() { return _contended_enter_count; } jlong contended_enter_ticks() { return _contended_enter_ticks; } jlong monitor_wait_count() { return _monitor_wait_count; } jlong monitor_wait_ticks() { return _monitor_wait_ticks; } jlong sleep_count() { return _sleep_count; } jlong sleep_ticks() { return _sleep_ticks; } oop blocker_object() { return _blocker_object; } oop blocker_object_owner() { return _blocker_object_owner; } ThreadSnapshot* next() const { return _next; } ThreadStackTrace* get_stack_trace() { return _stack_trace; } ThreadConcurrentLocks* get_concurrent_locks() { return _concurrent_locks; } void dump_stack_at_safepoint(int max_depth, bool with_locked_monitors); void set_concurrent_locks(ThreadConcurrentLocks* l) { _concurrent_locks = l; } void oops_do(OopClosure* f); void metadata_do(void f(Metadata*)); }; class ThreadStackTrace : public CHeapObj { private: JavaThread* _thread; int _depth; // number of stack frames added bool _with_locked_monitors; GrowableArray* _frames; GrowableArray* _jni_locked_monitors; public: ThreadStackTrace(JavaThread* thread, bool with_locked_monitors); ~ThreadStackTrace(); JavaThread* thread() { return _thread; } StackFrameInfo* stack_frame_at(int i) { return _frames->at(i); } int get_stack_depth() { return _depth; } void add_stack_frame(javaVFrame* jvf); void dump_stack_at_safepoint(int max_depth); Handle allocate_fill_stack_trace_element_array(TRAPS); void oops_do(OopClosure* f); void metadata_do(void f(Metadata*)); GrowableArray* jni_locked_monitors() { return _jni_locked_monitors; } int num_jni_locked_monitors() { return (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0); } bool is_owned_monitor_on_stack(oop object); void add_jni_locked_monitor(oop object) { _jni_locked_monitors->append(object); } }; // StackFrameInfo for keeping Method* and bci during // stack walking for later construction of StackTraceElement[] // Java instances class StackFrameInfo : public CHeapObj { private: Method* _method; int _bci; GrowableArray* _locked_monitors; // list of object monitors locked by this frame // We need to save the mirrors in the backtrace to keep the class // from being unloaded while we still have this stack trace. oop _class_holder; public: StackFrameInfo(javaVFrame* jvf, bool with_locked_monitors); ~StackFrameInfo() { if (_locked_monitors != NULL) { delete _locked_monitors; } }; Method* method() const { return _method; } int bci() const { return _bci; } void oops_do(OopClosure* f); void metadata_do(void f(Metadata*)); int num_locked_monitors() { return (_locked_monitors != NULL ? _locked_monitors->length() : 0); } GrowableArray* locked_monitors() { return _locked_monitors; } void print_on(outputStream* st) const; }; class ThreadConcurrentLocks : public CHeapObj { private: GrowableArray* _owned_locks; ThreadConcurrentLocks* _next; // This JavaThread* is protected in one of two different ways // depending on the usage of the ThreadConcurrentLocks object: // 1) by being stored in objects that are only allocated and used at a // safepoint (ConcurrentLocksDump), or 2) by being stored in objects // that are protected by a ThreadsListSetter (ThreadSnapshot inside // ThreadDumpResult). JavaThread* _thread; public: ThreadConcurrentLocks(JavaThread* thread); ~ThreadConcurrentLocks(); void add_lock(instanceOop o); void set_next(ThreadConcurrentLocks* n) { _next = n; } ThreadConcurrentLocks* next() { return _next; } JavaThread* java_thread() { return _thread; } GrowableArray* owned_locks() { return _owned_locks; } void oops_do(OopClosure* f); }; class ConcurrentLocksDump : public StackObj { private: ThreadConcurrentLocks* _map; ThreadConcurrentLocks* _last; // Last ThreadConcurrentLocks in the map bool _retain_map_on_free; void build_map(GrowableArray* aos_objects); void add_lock(JavaThread* thread, instanceOop o); public: ConcurrentLocksDump(bool retain_map_on_free) : _map(NULL), _last(NULL), _retain_map_on_free(retain_map_on_free) { assert(SafepointSynchronize::is_at_safepoint(), "Must be constructed at a safepoint."); }; ConcurrentLocksDump() : _map(NULL), _last(NULL), _retain_map_on_free(false) { assert(SafepointSynchronize::is_at_safepoint(), "Must be constructed at a safepoint."); }; ~ConcurrentLocksDump(); void dump_at_safepoint(); ThreadConcurrentLocks* thread_concurrent_locks(JavaThread* thread); void print_locks_on(JavaThread* t, outputStream* st); }; class ThreadDumpResult : public StackObj { private: int _num_threads; int _num_snapshots; ThreadSnapshot* _snapshots; ThreadSnapshot* _last; ThreadDumpResult* _next; ThreadsListSetter _setter; // Helper to set hazard ptr in the originating thread // which protects the JavaThreads in _snapshots. public: ThreadDumpResult(); ThreadDumpResult(int num_threads); ~ThreadDumpResult(); void add_thread_snapshot(ThreadSnapshot* ts); void set_next(ThreadDumpResult* next) { _next = next; } ThreadDumpResult* next() { return _next; } int num_threads() { return _num_threads; } int num_snapshots() { return _num_snapshots; } ThreadSnapshot* snapshots() { return _snapshots; } void set_t_list() { _setter.set(); } ThreadsList* t_list(); bool t_list_has_been_set() { return _setter.target_needs_release(); } void oops_do(OopClosure* f); void metadata_do(void f(Metadata*)); }; class DeadlockCycle : public CHeapObj { private: bool _is_deadlock; GrowableArray* _threads; DeadlockCycle* _next; public: DeadlockCycle(); ~DeadlockCycle(); DeadlockCycle* next() { return _next; } void set_next(DeadlockCycle* d) { _next = d; } void add_thread(JavaThread* t) { _threads->append(t); } void reset() { _is_deadlock = false; _threads->clear(); } void set_deadlock(bool value) { _is_deadlock = value; } bool is_deadlock() { return _is_deadlock; } int num_threads() { return _threads->length(); } GrowableArray* threads() { return _threads; } void print_on_with(ThreadsList * t_list, outputStream* st) const; }; // Utility class to get list of java threads. class ThreadsListEnumerator : public StackObj { private: GrowableArray* _threads_array; public: ThreadsListEnumerator(Thread* cur_thread, bool include_jvmti_agent_threads = false, bool include_jni_attaching_threads = true); int num_threads() { return _threads_array->length(); } instanceHandle get_threadObj(int index) { return _threads_array->at(index); } }; // abstract utility class to set new thread states, and restore previous after the block exits class JavaThreadStatusChanger : public StackObj { private: java_lang_Thread::ThreadStatus _old_state; JavaThread* _java_thread; bool _is_alive; void save_old_state(JavaThread* java_thread) { _java_thread = java_thread; _is_alive = is_alive(java_thread); if (is_alive()) { _old_state = java_lang_Thread::get_thread_status(_java_thread->threadObj()); } } public: static void set_thread_status(JavaThread* java_thread, java_lang_Thread::ThreadStatus state) { java_lang_Thread::set_thread_status(java_thread->threadObj(), state); } void set_thread_status(java_lang_Thread::ThreadStatus state) { if (is_alive()) { set_thread_status(_java_thread, state); } } JavaThreadStatusChanger(JavaThread* java_thread, java_lang_Thread::ThreadStatus state) : _old_state(java_lang_Thread::NEW) { save_old_state(java_thread); set_thread_status(state); } JavaThreadStatusChanger(JavaThread* java_thread) : _old_state(java_lang_Thread::NEW) { save_old_state(java_thread); } ~JavaThreadStatusChanger() { set_thread_status(_old_state); } static bool is_alive(JavaThread* java_thread) { return java_thread != NULL && java_thread->threadObj() != NULL; } bool is_alive() { return _is_alive; } }; // Change status to waiting on an object (timed or indefinite) class JavaThreadInObjectWaitState : public JavaThreadStatusChanger { private: ThreadStatistics* _stat; bool _active; public: JavaThreadInObjectWaitState(JavaThread *java_thread, bool timed) : JavaThreadStatusChanger(java_thread, timed ? java_lang_Thread::IN_OBJECT_WAIT_TIMED : java_lang_Thread::IN_OBJECT_WAIT) { if (is_alive()) { _stat = java_thread->get_thread_stat(); _active = ThreadService::is_thread_monitoring_contention(); _stat->monitor_wait(); if (_active) { _stat->monitor_wait_begin(); } } else { _active = false; } } ~JavaThreadInObjectWaitState() { if (_active) { _stat->monitor_wait_end(); } } }; // Change status to parked (timed or indefinite) class JavaThreadParkedState : public JavaThreadStatusChanger { private: ThreadStatistics* _stat; bool _active; public: JavaThreadParkedState(JavaThread *java_thread, bool timed) : JavaThreadStatusChanger(java_thread, timed ? java_lang_Thread::PARKED_TIMED : java_lang_Thread::PARKED) { if (is_alive()) { _stat = java_thread->get_thread_stat(); _active = ThreadService::is_thread_monitoring_contention(); _stat->monitor_wait(); if (_active) { _stat->monitor_wait_begin(); } } else { _active = false; } } ~JavaThreadParkedState() { if (_active) { _stat->monitor_wait_end(); } } }; // Change status to blocked on (re-)entering a synchronization block class JavaThreadBlockedOnMonitorEnterState : public JavaThreadStatusChanger { private: ThreadStatistics* _stat; bool _active; static bool contended_enter_begin(JavaThread *java_thread) { set_thread_status(java_thread, java_lang_Thread::BLOCKED_ON_MONITOR_ENTER); ThreadStatistics* stat = java_thread->get_thread_stat(); stat->contended_enter(); bool active = ThreadService::is_thread_monitoring_contention(); if (active) { stat->contended_enter_begin(); } return active; } public: // java_thread is waiting thread being blocked on monitor reenter. // Current thread is the notifying thread which holds the monitor. static bool wait_reenter_begin(JavaThread *java_thread, ObjectMonitor *obj_m) { assert((java_thread != NULL), "Java thread should not be null here"); bool active = false; if (is_alive(java_thread) && ServiceUtil::visible_oop((oop)obj_m->object())) { active = contended_enter_begin(java_thread); } return active; } static void wait_reenter_end(JavaThread *java_thread, bool active) { if (active) { java_thread->get_thread_stat()->contended_enter_end(); } set_thread_status(java_thread, java_lang_Thread::RUNNABLE); } JavaThreadBlockedOnMonitorEnterState(JavaThread *java_thread, ObjectMonitor *obj_m) : _stat(NULL), _active(false), JavaThreadStatusChanger(java_thread) { assert((java_thread != NULL), "Java thread should not be null here"); // Change thread status and collect contended enter stats for monitor contended // enter done for external java world objects and it is contended. All other cases // like for vm internal objects and for external objects which are not contended // thread status is not changed and contended enter stat is not collected. _active = false; if (is_alive() && ServiceUtil::visible_oop((oop)obj_m->object()) && obj_m->contentions() > 0) { _stat = java_thread->get_thread_stat(); _active = contended_enter_begin(java_thread); } } ~JavaThreadBlockedOnMonitorEnterState() { if (_active) { _stat->contended_enter_end(); } } }; // Change status to sleeping class JavaThreadSleepState : public JavaThreadStatusChanger { private: ThreadStatistics* _stat; bool _active; public: JavaThreadSleepState(JavaThread *java_thread) : JavaThreadStatusChanger(java_thread, java_lang_Thread::SLEEPING) { if (is_alive()) { _stat = java_thread->get_thread_stat(); _active = ThreadService::is_thread_monitoring_contention(); _stat->thread_sleep(); if (_active) { _stat->thread_sleep_begin(); } } else { _active = false; } } ~JavaThreadSleepState() { if (_active) { _stat->thread_sleep_end(); } } }; #endif // SHARE_VM_SERVICES_THREADSERVICE_HPP