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src/hotspot/share/runtime/thread.cpp

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rev 48154 : 8191789: migrate more Thread-SMR stuff from thread.[ch]pp -> threadSMR.[ch]pp
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*** 105,115 **** #include "utilities/defaultStream.hpp" #include "utilities/dtrace.hpp" #include "utilities/events.hpp" #include "utilities/macros.hpp" #include "utilities/preserveException.hpp" - #include "utilities/resourceHash.hpp" #include "utilities/vmError.hpp" #if INCLUDE_ALL_GCS #include "gc/cms/concurrentMarkSweepThread.hpp" #include "gc/g1/concurrentMarkThread.inline.hpp" #include "gc/parallel/pcTasks.hpp" --- 105,114 ----
*** 205,215 **** } } void JavaThread::smr_delete() { if (_on_thread_list) { ! Threads::smr_delete(this); } else { delete this; } } --- 204,214 ---- } } void JavaThread::smr_delete() { if (_on_thread_list) { ! ThreadsSMRSupport::smr_delete(this); } else { delete this; } }
*** 417,427 **** // void Thread::check_for_dangling_thread_pointer(Thread *thread) { assert(!thread->is_Java_thread() || Thread::current() == thread || !((JavaThread *) thread)->on_thread_list() || SafepointSynchronize::is_at_safepoint() || ! Threads::is_a_protected_JavaThread_with_lock((JavaThread *) thread), "possibility of dangling Thread pointer"); } #endif ThreadPriority Thread::get_priority(const Thread* const thread) { --- 416,426 ---- // void Thread::check_for_dangling_thread_pointer(Thread *thread) { assert(!thread->is_Java_thread() || Thread::current() == thread || !((JavaThread *) thread)->on_thread_list() || SafepointSynchronize::is_at_safepoint() || ! ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), "possibility of dangling Thread pointer"); } #endif ThreadPriority Thread::get_priority(const Thread* const thread) {
*** 3447,3544 **** int Threads::_number_of_threads = 0; int Threads::_number_of_non_daemon_threads = 0; int Threads::_return_code = 0; int Threads::_thread_claim_parity = 0; size_t JavaThread::_stack_size_at_create = 0; - // Safe Memory Reclamation (SMR) support: - Monitor* Threads::_smr_delete_lock = - new Monitor(Monitor::special, "smr_delete_lock", - false /* allow_vm_block */, - Monitor::_safepoint_check_never); - // The '_cnt', '_max' and '_times" fields are enabled via - // -XX:+EnableThreadSMRStatistics: - - // # of parallel threads in _smr_delete_lock->wait(). - // Impl note: Hard to imagine > 64K waiting threads so this could be 16-bit, - // but there is no nice 16-bit _FORMAT support. - uint Threads::_smr_delete_lock_wait_cnt = 0; - - // Max # of parallel threads in _smr_delete_lock->wait(). - // Impl note: See _smr_delete_lock_wait_cnt note. - uint Threads::_smr_delete_lock_wait_max = 0; - - // Flag to indicate when an _smr_delete_lock->notify() is needed. - // Impl note: See _smr_delete_lock_wait_cnt note. - volatile uint Threads::_smr_delete_notify = 0; - - // # of threads deleted over VM lifetime. - // Impl note: Atomically incremented over VM lifetime so use unsigned for more - // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc - // isn't available everywhere (or is it?). - volatile uint Threads::_smr_deleted_thread_cnt = 0; - - // Max time in millis to delete a thread. - // Impl note: 16-bit might be too small on an overloaded machine. Use - // unsigned since this is a time value. Set via Atomic::cmpxchg() in a - // loop for correctness. - volatile uint Threads::_smr_deleted_thread_time_max = 0; - - // Cumulative time in millis to delete threads. - // Impl note: Atomically added to over VM lifetime so use unsigned for more - // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc - // isn't available everywhere (or is it?). - volatile uint Threads::_smr_deleted_thread_times = 0; - - ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0); - - // # of ThreadsLists allocated over VM lifetime. - // Impl note: We allocate a new ThreadsList for every thread create and - // every thread delete so we need a bigger type than the - // _smr_deleted_thread_cnt field. - uint64_t Threads::_smr_java_thread_list_alloc_cnt = 1; - - // # of ThreadsLists freed over VM lifetime. - // Impl note: See _smr_java_thread_list_alloc_cnt note. - uint64_t Threads::_smr_java_thread_list_free_cnt = 0; - - // Max size ThreadsList allocated. - // Impl note: Max # of threads alive at one time should fit in unsigned 32-bit. - uint Threads::_smr_java_thread_list_max = 0; - - // Max # of nested ThreadsLists for a thread. - // Impl note: Hard to imagine > 64K nested ThreadsLists so this could be - // 16-bit, but there is no nice 16-bit _FORMAT support. - uint Threads::_smr_nested_thread_list_max = 0; - - // # of ThreadsListHandles deleted over VM lifetime. - // Impl note: Atomically incremented over VM lifetime so use unsigned for - // more range. There will be fewer ThreadsListHandles than threads so - // unsigned 32-bit should be fine. - volatile uint Threads::_smr_tlh_cnt = 0; - - // Max time in millis to delete a ThreadsListHandle. - // Impl note: 16-bit might be too small on an overloaded machine. Use - // unsigned since this is a time value. Set via Atomic::cmpxchg() in a - // loop for correctness. - volatile uint Threads::_smr_tlh_time_max = 0; - - // Cumulative time in millis to delete ThreadsListHandles. - // Impl note: Atomically added to over VM lifetime so use unsigned for more - // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc - // isn't available everywhere (or is it?). - volatile uint Threads::_smr_tlh_times = 0; - - ThreadsList* Threads::_smr_to_delete_list = NULL; - - // # of parallel ThreadsLists on the to-delete list. - // Impl note: Hard to imagine > 64K ThreadsLists needing to be deleted so - // this could be 16-bit, but there is no nice 16-bit _FORMAT support. - uint Threads::_smr_to_delete_list_cnt = 0; - - // Max # of parallel ThreadsLists on the to-delete list. - // Impl note: See _smr_to_delete_list_cnt note. - uint Threads::_smr_to_delete_list_max = 0; #ifdef ASSERT bool Threads::_vm_complete = false; #endif --- 3446,3455 ----
*** 3559,3574 **** *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ MACRO_current_p != MACRO_end; \ MACRO_current_p++, \ X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) - inline ThreadsList* Threads::get_smr_java_thread_list() { - return (ThreadsList*)OrderAccess::load_acquire(&_smr_java_thread_list); - } - // All JavaThreads ! #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(get_smr_java_thread_list(), X) // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) void Threads::threads_do(ThreadClosure* tc) { assert_locked_or_safepoint(Threads_lock); // ALL_JAVA_THREADS iterates through all JavaThreads --- 3470,3481 ---- *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ MACRO_current_p != MACRO_end; \ MACRO_current_p++, \ X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) // All JavaThreads ! #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_smr_java_thread_list(), X) // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) void Threads::threads_do(ThreadClosure* tc) { assert_locked_or_safepoint(Threads_lock); // ALL_JAVA_THREADS iterates through all JavaThreads
*** 3665,3908 **** JavaValue result(T_VOID); JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), vmSymbols::void_method_signature(), CHECK); } - // Safe Memory Reclamation (SMR) support: - // - - // Acquire a stable ThreadsList. - // - ThreadsList *Threads::acquire_stable_list(Thread *self, bool is_ThreadsListSetter) { - assert(self != NULL, "sanity check"); - // acquire_stable_list_nested_path() will grab the Threads_lock - // so let's make sure the ThreadsListHandle is in a safe place. - // ThreadsListSetter cannot make this check on this code path. - debug_only(if (!is_ThreadsListSetter && StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);) - - if (self->get_threads_hazard_ptr() == NULL) { - // The typical case is first. - return acquire_stable_list_fast_path(self); - } - - // The nested case is rare. - return acquire_stable_list_nested_path(self); - } - - // Fast path (and lock free) way to acquire a stable ThreadsList. - // - ThreadsList *Threads::acquire_stable_list_fast_path(Thread *self) { - assert(self != NULL, "sanity check"); - assert(self->get_threads_hazard_ptr() == NULL, "sanity check"); - assert(self->get_nested_threads_hazard_ptr() == NULL, - "cannot have a nested hazard ptr with a NULL regular hazard ptr"); - - ThreadsList* threads; - - // Stable recording of a hazard ptr for SMR. This code does not use - // locks so its use of the _smr_java_thread_list & _threads_hazard_ptr - // fields is racy relative to code that uses those fields with locks. - // OrderAccess and Atomic functions are used to deal with those races. - // - while (true) { - threads = get_smr_java_thread_list(); - - // Publish a tagged hazard ptr to denote that the hazard ptr is not - // yet verified as being stable. Due to the fence after the hazard - // ptr write, it will be sequentially consistent w.r.t. the - // sequentially consistent writes of the ThreadsList, even on - // non-multiple copy atomic machines where stores can be observed - // in different order from different observer threads. - ThreadsList* unverified_threads = Thread::tag_hazard_ptr(threads); - self->set_threads_hazard_ptr(unverified_threads); - - // If _smr_java_thread_list has changed, we have lost a race with - // Threads::add() or Threads::remove() and have to try again. - if (get_smr_java_thread_list() != threads) { - continue; - } - - // We try to remove the tag which will verify the hazard ptr as - // being stable. This exchange can race with a scanning thread - // which might invalidate the tagged hazard ptr to keep it from - // being followed to access JavaThread ptrs. If we lose the race, - // we simply retry. If we win the race, then the stable hazard - // ptr is officially published. - if (self->cmpxchg_threads_hazard_ptr(threads, unverified_threads) == unverified_threads) { - break; - } - } - - // A stable hazard ptr has been published letting other threads know - // that the ThreadsList and the JavaThreads reachable from this list - // are protected and hence they should not be deleted until everyone - // agrees it is safe to do so. - - return threads; - } - - // Acquire a nested stable ThreadsList; this is rare so it uses - // Threads_lock. - // - ThreadsList *Threads::acquire_stable_list_nested_path(Thread *self) { - assert(self != NULL, "sanity check"); - assert(self->get_threads_hazard_ptr() != NULL, - "cannot have a NULL regular hazard ptr when acquiring a nested hazard ptr"); - - // The thread already has a hazard ptr (ThreadsList ref) so we need - // to create a nested ThreadsListHandle with the current ThreadsList - // since it might be different than our current hazard ptr. The need - // for a nested ThreadsListHandle is rare so we do this while holding - // the Threads_lock so we don't race with the scanning code; the code - // is so much simpler this way. - - NestedThreadsList* node; - { - // Only grab the Threads_lock if we don't already own it. - MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock); - node = new NestedThreadsList(get_smr_java_thread_list()); - // We insert at the front of the list to match up with the delete - // in release_stable_list(). - node->set_next(self->get_nested_threads_hazard_ptr()); - self->set_nested_threads_hazard_ptr(node); - if (EnableThreadSMRStatistics) { - self->inc_nested_threads_hazard_ptr_cnt(); - if (self->nested_threads_hazard_ptr_cnt() > _smr_nested_thread_list_max) { - _smr_nested_thread_list_max = self->nested_threads_hazard_ptr_cnt(); - } - } - } - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::acquire_stable_list: add NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list())); - - return node->t_list(); - } - - inline void Threads::add_smr_deleted_thread_times(uint add_value) { - Atomic::add(add_value, &_smr_deleted_thread_times); - } - - inline void Threads::inc_smr_deleted_thread_cnt() { - Atomic::inc(&_smr_deleted_thread_cnt); - } - - // Release a stable ThreadsList. - // - void Threads::release_stable_list(Thread *self) { - assert(self != NULL, "sanity check"); - // release_stable_list_nested_path() will grab the Threads_lock - // so let's make sure the ThreadsListHandle is in a safe place. - debug_only(if (StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);) - - if (self->get_nested_threads_hazard_ptr() == NULL) { - // The typical case is first. - release_stable_list_fast_path(self); - return; - } - - // The nested case is rare. - release_stable_list_nested_path(self); - } - - // Fast path way to release a stable ThreadsList. The release portion - // is lock-free, but the wake up portion is not. - // - void Threads::release_stable_list_fast_path(Thread *self) { - assert(self != NULL, "sanity check"); - assert(self->get_threads_hazard_ptr() != NULL, "sanity check"); - assert(self->get_nested_threads_hazard_ptr() == NULL, - "cannot have a nested hazard ptr when releasing a regular hazard ptr"); - - // After releasing the hazard ptr, other threads may go ahead and - // free up some memory temporarily used by a ThreadsList snapshot. - self->set_threads_hazard_ptr(NULL); - - // We use double-check locking to reduce traffic on the system - // wide smr_delete_lock. - if (Threads::smr_delete_notify()) { - // An exiting thread might be waiting in smr_delete(); we need to - // check with smr_delete_lock to be sure. - release_stable_list_wake_up((char *) "regular hazard ptr"); - } - } - - // Release a nested stable ThreadsList; this is rare so it uses - // Threads_lock. - // - void Threads::release_stable_list_nested_path(Thread *self) { - assert(self != NULL, "sanity check"); - assert(self->get_nested_threads_hazard_ptr() != NULL, "sanity check"); - assert(self->get_threads_hazard_ptr() != NULL, - "must have a regular hazard ptr to have nested hazard ptrs"); - - // We have a nested ThreadsListHandle so we have to release it first. - // The need for a nested ThreadsListHandle is rare so we do this while - // holding the Threads_lock so we don't race with the scanning code; - // the code is so much simpler this way. - - NestedThreadsList *node; - { - // Only grab the Threads_lock if we don't already own it. - MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock); - // We remove from the front of the list to match up with the insert - // in acquire_stable_list(). - node = self->get_nested_threads_hazard_ptr(); - self->set_nested_threads_hazard_ptr(node->next()); - if (EnableThreadSMRStatistics) { - self->dec_nested_threads_hazard_ptr_cnt(); - } - } - - // An exiting thread might be waiting in smr_delete(); we need to - // check with smr_delete_lock to be sure. - release_stable_list_wake_up((char *) "nested hazard ptr"); - - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list: delete NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list())); - - delete node; - } - - // Wake up portion of the release stable ThreadsList protocol; - // uses the smr_delete_lock(). - // - void Threads::release_stable_list_wake_up(char *log_str) { - assert(log_str != NULL, "sanity check"); - - // Note: smr_delete_lock is held in smr_delete() for the entire - // hazard ptr search so that we do not lose this notify() if - // the exiting thread has to wait. That code path also holds - // Threads_lock (which was grabbed before smr_delete_lock) so that - // threads_do() can be called. This means the system can't start a - // safepoint which means this thread can't take too long to get to - // a safepoint because of being blocked on smr_delete_lock. - // - MonitorLockerEx ml(Threads::smr_delete_lock(), Monitor::_no_safepoint_check_flag); - if (Threads::smr_delete_notify()) { - // Notify any exiting JavaThreads that are waiting in smr_delete() - // that we've released a ThreadsList. - ml.notify_all(); - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list notified %s", os::current_thread_id(), log_str); - } - } - - inline void Threads::update_smr_deleted_thread_time_max(uint new_value) { - while (true) { - uint cur_value = _smr_deleted_thread_time_max; - if (new_value <= cur_value) { - // No need to update max value so we're done. - break; - } - if (Atomic::cmpxchg(new_value, &_smr_deleted_thread_time_max, cur_value) == cur_value) { - // Updated max value so we're done. Otherwise try it all again. - break; - } - } - } - - inline ThreadsList* Threads::xchg_smr_java_thread_list(ThreadsList* new_list) { - return (ThreadsList*)Atomic::xchg(new_list, &_smr_java_thread_list); - } - void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); if (EagerXrunInit && Arguments::init_libraries_at_startup()) { create_vm_init_libraries(); --- 3572,3581 ----
*** 4664,5168 **** if (version == JNI_VERSION_9) return JNI_TRUE; if (version == JNI_VERSION_10) return JNI_TRUE; return JNI_FALSE; } - // Hash table of pointers found by a scan. Used for collecting hazard - // pointers (ThreadsList references). Also used for collecting JavaThreads - // that are indirectly referenced by hazard ptrs. An instance of this - // class only contains one type of pointer. - // - class ThreadScanHashtable : public CHeapObj<mtThread> { - private: - static bool ptr_equals(void * const& s1, void * const& s2) { - return s1 == s2; - } - - static unsigned int ptr_hash(void * const& s1) { - // 2654435761 = 2^32 * Phi (golden ratio) - return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u); - } - - int _table_size; - // ResourceHashtable SIZE is specified at compile time so our - // dynamic _table_size is unused for now; 1031 is the first prime - // after 1024. - typedef ResourceHashtable<void *, int, &ThreadScanHashtable::ptr_hash, - &ThreadScanHashtable::ptr_equals, 1031, - ResourceObj::C_HEAP, mtThread> PtrTable; - PtrTable * _ptrs; - - public: - // ResourceHashtable is passed to various functions and populated in - // different places so we allocate it using C_HEAP to make it immune - // from any ResourceMarks that happen to be in the code paths. - ThreadScanHashtable(int table_size) : _table_size(table_size), _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()) {} - - ~ThreadScanHashtable() { delete _ptrs; } - - bool has_entry(void *pointer) { - int *val_ptr = _ptrs->get(pointer); - return val_ptr != NULL && *val_ptr == 1; - } - - void add_entry(void *pointer) { - _ptrs->put(pointer, 1); - } - }; - - // Closure to gather JavaThreads indirectly referenced by hazard ptrs - // (ThreadsList references) into a hash table. This closure handles part 2 - // of the dance - adding all the JavaThreads referenced by the hazard - // pointer (ThreadsList reference) to the hash table. - // - class AddThreadHazardPointerThreadClosure : public ThreadClosure { - private: - ThreadScanHashtable *_table; - - public: - AddThreadHazardPointerThreadClosure(ThreadScanHashtable *table) : _table(table) {} - - virtual void do_thread(Thread *thread) { - if (!_table->has_entry((void*)thread)) { - // The same JavaThread might be on more than one ThreadsList or - // more than one thread might be using the same ThreadsList. In - // either case, we only need a single entry for a JavaThread. - _table->add_entry((void*)thread); - } - } - }; - - // Closure to gather JavaThreads indirectly referenced by hazard ptrs - // (ThreadsList references) into a hash table. This closure handles part 1 - // of the dance - hazard ptr chain walking and dispatch to another - // closure. - // - class ScanHazardPtrGatherProtectedThreadsClosure : public ThreadClosure { - private: - ThreadScanHashtable *_table; - public: - ScanHazardPtrGatherProtectedThreadsClosure(ThreadScanHashtable *table) : _table(table) {} - - virtual void do_thread(Thread *thread) { - assert_locked_or_safepoint(Threads_lock); - - if (thread == NULL) return; - - // This code races with Threads::acquire_stable_list() which is - // lock-free so we have to handle some special situations. - // - ThreadsList *current_list = NULL; - while (true) { - current_list = thread->get_threads_hazard_ptr(); - // No hazard ptr so nothing more to do. - if (current_list == NULL) { - assert(thread->get_nested_threads_hazard_ptr() == NULL, - "cannot have a nested hazard ptr with a NULL regular hazard ptr"); - return; - } - - // If the hazard ptr is verified as stable (since it is not tagged), - // then it is safe to use. - if (!Thread::is_hazard_ptr_tagged(current_list)) break; - - // The hazard ptr is tagged as not yet verified as being stable - // so we are racing with acquire_stable_list(). This exchange - // attempts to invalidate the hazard ptr. If we win the race, - // then we can ignore this unstable hazard ptr and the other - // thread will retry the attempt to publish a stable hazard ptr. - // If we lose the race, then we retry our attempt to look at the - // hazard ptr. - if (thread->cmpxchg_threads_hazard_ptr(NULL, current_list) == current_list) return; - } - - // The current JavaThread has a hazard ptr (ThreadsList reference) - // which might be _smr_java_thread_list or it might be an older - // ThreadsList that has been removed but not freed. In either case, - // the hazard ptr is protecting all the JavaThreads on that - // ThreadsList. - AddThreadHazardPointerThreadClosure add_cl(_table); - current_list->threads_do(&add_cl); - - // Any NestedThreadsLists are also protecting JavaThreads so - // gather those also; the ThreadsLists may be different. - for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); - node != NULL; node = node->next()) { - node->t_list()->threads_do(&add_cl); - } - } - }; - - // Closure to print JavaThreads that have a hazard ptr (ThreadsList - // reference) that contains an indirect reference to a specific JavaThread. - // - class ScanHazardPtrPrintMatchingThreadsClosure : public ThreadClosure { - private: - JavaThread *_thread; - public: - ScanHazardPtrPrintMatchingThreadsClosure(JavaThread *thread) : _thread(thread) {} - - virtual void do_thread(Thread *thread) { - assert_locked_or_safepoint(Threads_lock); - - if (thread == NULL) return; - ThreadsList *current_list = thread->get_threads_hazard_ptr(); - if (current_list == NULL) { - assert(thread->get_nested_threads_hazard_ptr() == NULL, - "cannot have a nested hazard ptr with a NULL regular hazard ptr"); - return; - } - // If the hazard ptr is unverified, then ignore it. - if (Thread::is_hazard_ptr_tagged(current_list)) return; - - // The current JavaThread has a hazard ptr (ThreadsList reference) - // which might be _smr_java_thread_list or it might be an older - // ThreadsList that has been removed but not freed. In either case, - // the hazard ptr is protecting all the JavaThreads on that - // ThreadsList, but we only care about matching a specific JavaThread. - DO_JAVA_THREADS(current_list, p) { - if (p == _thread) { - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread)); - break; - } - } - - // Any NestedThreadsLists are also protecting JavaThreads so - // check those also; the ThreadsLists may be different. - for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); - node != NULL; node = node->next()) { - DO_JAVA_THREADS(node->t_list(), p) { - if (p == _thread) { - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a nested hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread)); - return; - } - } - } - } - }; - - // Return true if the specified JavaThread is protected by a hazard - // pointer (ThreadsList reference). Otherwise, returns false. - // - bool Threads::is_a_protected_JavaThread(JavaThread *thread) { - assert_locked_or_safepoint(Threads_lock); - - // Hash table size should be first power of two higher than twice - // the length of the Threads list. - int hash_table_size = MIN2(_number_of_threads, 32) << 1; - hash_table_size--; - hash_table_size |= hash_table_size >> 1; - hash_table_size |= hash_table_size >> 2; - hash_table_size |= hash_table_size >> 4; - hash_table_size |= hash_table_size >> 8; - hash_table_size |= hash_table_size >> 16; - hash_table_size++; - - // Gather a hash table of the JavaThreads indirectly referenced by - // hazard ptrs. - ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size); - ScanHazardPtrGatherProtectedThreadsClosure scan_cl(scan_table); - Threads::threads_do(&scan_cl); - - bool thread_is_protected = false; - if (scan_table->has_entry((void*)thread)) { - thread_is_protected = true; - } - delete scan_table; - return thread_is_protected; - } - - // Safely delete a JavaThread when it is no longer in use by a - // ThreadsListHandle. - // - void Threads::smr_delete(JavaThread *thread) { - assert(!Threads_lock->owned_by_self(), "sanity"); - - bool has_logged_once = false; - elapsedTimer timer; - if (EnableThreadSMRStatistics) { - timer.start(); - } - - while (true) { - { - // No safepoint check because this JavaThread is not on the - // Threads list. - MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); - // Cannot use a MonitorLockerEx helper here because we have - // to drop the Threads_lock first if we wait. - Threads::smr_delete_lock()->lock_without_safepoint_check(); - // Set the smr_delete_notify flag after we grab smr_delete_lock - // and before we scan hazard ptrs because we're doing - // double-check locking in release_stable_list(). - Threads::set_smr_delete_notify(); - - if (!is_a_protected_JavaThread(thread)) { - // This is the common case. - Threads::clear_smr_delete_notify(); - Threads::smr_delete_lock()->unlock(); - break; - } - if (!has_logged_once) { - has_logged_once = true; - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is not deleted.", os::current_thread_id(), p2i(thread)); - if (log_is_enabled(Debug, os, thread)) { - ScanHazardPtrPrintMatchingThreadsClosure scan_cl(thread); - Threads::threads_do(&scan_cl); - } - } - } // We have to drop the Threads_lock to wait or delete the thread - - if (EnableThreadSMRStatistics) { - _smr_delete_lock_wait_cnt++; - if (_smr_delete_lock_wait_cnt > _smr_delete_lock_wait_max) { - _smr_delete_lock_wait_max = _smr_delete_lock_wait_cnt; - } - } - // Wait for a release_stable_list() call before we check again. No - // safepoint check, no timeout, and not as suspend equivalent flag - // because this JavaThread is not on the Threads list. - Threads::smr_delete_lock()->wait(Mutex::_no_safepoint_check_flag, 0, - !Mutex::_as_suspend_equivalent_flag); - if (EnableThreadSMRStatistics) { - _smr_delete_lock_wait_cnt--; - } - - Threads::clear_smr_delete_notify(); - Threads::smr_delete_lock()->unlock(); - // Retry the whole scenario. - } - - if (ThreadLocalHandshakes) { - // The thread is about to be deleted so cancel any handshake. - thread->cancel_handshake(); - } - - delete thread; - if (EnableThreadSMRStatistics) { - timer.stop(); - uint millis = (uint)timer.milliseconds(); - Threads::inc_smr_deleted_thread_cnt(); - Threads::add_smr_deleted_thread_times(millis); - Threads::update_smr_deleted_thread_time_max(millis); - } - - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is deleted.", os::current_thread_id(), p2i(thread)); - } - - bool Threads::smr_delete_notify() { - // Use load_acquire() in order to see any updates to _smr_delete_notify - // earlier than when smr_delete_lock is grabbed. - return (OrderAccess::load_acquire(&_smr_delete_notify) != 0); - } - - // set_smr_delete_notify() and clear_smr_delete_notify() are called - // under the protection of the smr_delete_lock, but we also use an - // Atomic operation to ensure the memory update is seen earlier than - // when the smr_delete_lock is dropped. - // - void Threads::set_smr_delete_notify() { - Atomic::inc(&_smr_delete_notify); - } - - void Threads::clear_smr_delete_notify() { - Atomic::dec(&_smr_delete_notify); - } - - // Closure to gather hazard ptrs (ThreadsList references) into a hash table. - // - class ScanHazardPtrGatherThreadsListClosure : public ThreadClosure { - private: - ThreadScanHashtable *_table; - public: - ScanHazardPtrGatherThreadsListClosure(ThreadScanHashtable *table) : _table(table) {} - - virtual void do_thread(Thread* thread) { - assert_locked_or_safepoint(Threads_lock); - - if (thread == NULL) return; - ThreadsList *threads = thread->get_threads_hazard_ptr(); - if (threads == NULL) { - assert(thread->get_nested_threads_hazard_ptr() == NULL, - "cannot have a nested hazard ptr with a NULL regular hazard ptr"); - return; - } - // In this closure we always ignore the tag that might mark this - // hazard ptr as not yet verified. If we happen to catch an - // unverified hazard ptr that is subsequently discarded (not - // published), then the only side effect is that we might keep a - // to-be-deleted ThreadsList alive a little longer. - threads = Thread::untag_hazard_ptr(threads); - if (!_table->has_entry((void*)threads)) { - _table->add_entry((void*)threads); - } - - // Any NestedThreadsLists are also protecting JavaThreads so - // gather those also; the ThreadsLists may be different. - for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); - node != NULL; node = node->next()) { - threads = node->t_list(); - if (!_table->has_entry((void*)threads)) { - _table->add_entry((void*)threads); - } - } - } - }; - - // Safely free a ThreadsList after a Threads::add() or Threads::remove(). - // The specified ThreadsList may not get deleted during this call if it - // is still in-use (referenced by a hazard ptr). Other ThreadsLists - // in the chain may get deleted by this call if they are no longer in-use. - void Threads::smr_free_list(ThreadsList* threads) { - assert_locked_or_safepoint(Threads_lock); - - threads->set_next_list(_smr_to_delete_list); - _smr_to_delete_list = threads; - if (EnableThreadSMRStatistics) { - _smr_to_delete_list_cnt++; - if (_smr_to_delete_list_cnt > _smr_to_delete_list_max) { - _smr_to_delete_list_max = _smr_to_delete_list_cnt; - } - } - - // Hash table size should be first power of two higher than twice the length of the ThreadsList - int hash_table_size = MIN2(_number_of_threads, 32) << 1; - hash_table_size--; - hash_table_size |= hash_table_size >> 1; - hash_table_size |= hash_table_size >> 2; - hash_table_size |= hash_table_size >> 4; - hash_table_size |= hash_table_size >> 8; - hash_table_size |= hash_table_size >> 16; - hash_table_size++; - - // Gather a hash table of the current hazard ptrs: - ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size); - ScanHazardPtrGatherThreadsListClosure scan_cl(scan_table); - Threads::threads_do(&scan_cl); - - // Walk through the linked list of pending freeable ThreadsLists - // and free the ones that are not referenced from hazard ptrs. - ThreadsList* current = _smr_to_delete_list; - ThreadsList* prev = NULL; - ThreadsList* next = NULL; - bool threads_is_freed = false; - while (current != NULL) { - next = current->next_list(); - if (!scan_table->has_entry((void*)current)) { - // This ThreadsList is not referenced by a hazard ptr. - if (prev != NULL) { - prev->set_next_list(next); - } - if (_smr_to_delete_list == current) { - _smr_to_delete_list = next; - } - - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is freed.", os::current_thread_id(), p2i(current)); - if (current == threads) threads_is_freed = true; - delete current; - if (EnableThreadSMRStatistics) { - _smr_java_thread_list_free_cnt++; - _smr_to_delete_list_cnt--; - } - } else { - prev = current; - } - current = next; - } - - if (!threads_is_freed) { - // Only report "is not freed" on the original call to - // smr_free_list() for this ThreadsList. - log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is not freed.", os::current_thread_id(), p2i(threads)); - } - - delete scan_table; - } - - // Remove a JavaThread from a ThreadsList. The returned ThreadsList is a - // new copy of the specified ThreadsList with the specified JavaThread - // removed. - ThreadsList *ThreadsList::remove_thread(ThreadsList* list, JavaThread* java_thread) { - assert(list->_length > 0, "sanity"); - - uint i = 0; - DO_JAVA_THREADS(list, current) { - if (current == java_thread) { - break; - } - i++; - } - assert(i < list->_length, "did not find JavaThread on the list"); - const uint index = i; - const uint new_length = list->_length - 1; - const uint head_length = index; - const uint tail_length = (new_length >= index) ? (new_length - index) : 0; - ThreadsList *const new_list = new ThreadsList(new_length); - - if (head_length > 0) { - Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length); - } - if (tail_length > 0) { - Copy::disjoint_words((HeapWord*)list->_threads + index + 1, (HeapWord*)new_list->_threads + index, tail_length); - } - - return new_list; - } - - // Add a JavaThread to a ThreadsList. The returned ThreadsList is a - // new copy of the specified ThreadsList with the specified JavaThread - // appended to the end. - ThreadsList *ThreadsList::add_thread(ThreadsList *list, JavaThread *java_thread) { - const uint index = list->_length; - const uint new_length = index + 1; - const uint head_length = index; - ThreadsList *const new_list = new ThreadsList(new_length); - - if (head_length > 0) { - Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length); - } - *(JavaThread**)(new_list->_threads + index) = java_thread; - - return new_list; - } - - int ThreadsList::find_index_of_JavaThread(JavaThread *target) { - if (target == NULL) { - return -1; - } - for (uint i = 0; i < length(); i++) { - if (target == thread_at(i)) { - return (int)i; - } - } - return -1; - } - - JavaThread* ThreadsList::find_JavaThread_from_java_tid(jlong java_tid) const { - DO_JAVA_THREADS(this, thread) { - oop tobj = thread->threadObj(); - // Ignore the thread if it hasn't run yet, has exited - // or is starting to exit. - if (tobj != NULL && !thread->is_exiting() && - java_tid == java_lang_Thread::thread_id(tobj)) { - // found a match - return thread; - } - } - return NULL; - } - - bool ThreadsList::includes(const JavaThread * const p) const { - if (p == NULL) { - return false; - } - DO_JAVA_THREADS(this, q) { - if (q == p) { - return true; - } - } - return false; - } void Threads::add(JavaThread* p, bool force_daemon) { // The threads lock must be owned at this point assert_locked_or_safepoint(Threads_lock); --- 4337,4346 ----
*** 5187,5208 **** } ThreadService::add_thread(p, daemon); // Maintain fast thread list ! ThreadsList *new_list = ThreadsList::add_thread(get_smr_java_thread_list(), p); if (EnableThreadSMRStatistics) { ! _smr_java_thread_list_alloc_cnt++; ! if (new_list->length() > _smr_java_thread_list_max) { ! _smr_java_thread_list_max = new_list->length(); ! } } // Initial _smr_java_thread_list will not generate a "Threads::add" mesg. log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list)); ! ThreadsList *old_list = xchg_smr_java_thread_list(new_list); ! smr_free_list(old_list); // Possible GC point. Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); } --- 4365,4384 ---- } ThreadService::add_thread(p, daemon); // Maintain fast thread list ! ThreadsList *new_list = ThreadsList::add_thread(ThreadsSMRSupport::get_smr_java_thread_list(), p); if (EnableThreadSMRStatistics) { ! ThreadsSMRSupport::inc_smr_java_thread_list_alloc_cnt(); ! ThreadsSMRSupport::update_smr_java_thread_list_max(new_list->length()); } // Initial _smr_java_thread_list will not generate a "Threads::add" mesg. log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list)); ! ThreadsList *old_list = ThreadsSMRSupport::xchg_smr_java_thread_list(new_list); ! ThreadsSMRSupport::smr_free_list(old_list); // Possible GC point. Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); }
*** 5213,5236 **** // Extra scope needed for Thread_lock, so we can check // that we do not remove thread without safepoint code notice { MutexLocker ml(Threads_lock); ! assert(get_smr_java_thread_list()->includes(p), "p must be present"); // Maintain fast thread list ! ThreadsList *new_list = ThreadsList::remove_thread(get_smr_java_thread_list(), p); if (EnableThreadSMRStatistics) { ! _smr_java_thread_list_alloc_cnt++; // This list is smaller so no need to check for a "longest" update. } // Final _smr_java_thread_list will not generate a "Threads::remove" mesg. log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list)); ! ThreadsList *old_list = xchg_smr_java_thread_list(new_list); ! smr_free_list(old_list); JavaThread* current = _thread_list; JavaThread* prev = NULL; while (current != p) { --- 4389,4412 ---- // Extra scope needed for Thread_lock, so we can check // that we do not remove thread without safepoint code notice { MutexLocker ml(Threads_lock); ! assert(ThreadsSMRSupport::get_smr_java_thread_list()->includes(p), "p must be present"); // Maintain fast thread list ! ThreadsList *new_list = ThreadsList::remove_thread(ThreadsSMRSupport::get_smr_java_thread_list(), p); if (EnableThreadSMRStatistics) { ! ThreadsSMRSupport::inc_smr_java_thread_list_alloc_cnt(); // This list is smaller so no need to check for a "longest" update. } // Final _smr_java_thread_list will not generate a "Threads::remove" mesg. log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list)); ! ThreadsList *old_list = ThreadsSMRSupport::xchg_smr_java_thread_list(new_list); ! ThreadsSMRSupport::smr_free_list(old_list); JavaThread* current = _thread_list; JavaThread* prev = NULL; while (current != p) {
*** 5451,5461 **** if (print_concurrent_locks) { concurrent_locks.dump_at_safepoint(); } #endif // INCLUDE_SERVICES ! print_smr_info_on(st); st->cr(); ALL_JAVA_THREADS(p) { ResourceMark rm; p->print_on(st); --- 4627,4637 ---- if (print_concurrent_locks) { concurrent_locks.dump_at_safepoint(); } #endif // INCLUDE_SERVICES ! ThreadsSMRSupport::print_smr_info_on(st); st->cr(); ALL_JAVA_THREADS(p) { ResourceMark rm; p->print_on(st);
*** 5484,5588 **** } st->flush(); } - // Log Threads class SMR info. - void Threads::log_smr_statistics() { - LogTarget(Info, thread, smr) log; - if (log.is_enabled()) { - LogStream out(log); - print_smr_info_on(&out); - } - } - - // Print Threads class SMR info. - void Threads::print_smr_info_on(outputStream* st) { - // Only grab the Threads_lock if we don't already own it - // and if we are not reporting an error. - MutexLockerEx ml((Threads_lock->owned_by_self() || VMError::is_error_reported()) ? NULL : Threads_lock); - - st->print_cr("Threads class SMR info:"); - st->print_cr("_smr_java_thread_list=" INTPTR_FORMAT ", length=%u, " - "elements={", p2i(_smr_java_thread_list), - _smr_java_thread_list->length()); - print_smr_info_elements_on(st, _smr_java_thread_list); - st->print_cr("}"); - if (_smr_to_delete_list != NULL) { - st->print_cr("_smr_to_delete_list=" INTPTR_FORMAT ", length=%u, " - "elements={", p2i(_smr_to_delete_list), - _smr_to_delete_list->length()); - print_smr_info_elements_on(st, _smr_to_delete_list); - st->print_cr("}"); - for (ThreadsList *t_list = _smr_to_delete_list->next_list(); - t_list != NULL; t_list = t_list->next_list()) { - st->print("next-> " INTPTR_FORMAT ", length=%u, " - "elements={", p2i(t_list), t_list->length()); - print_smr_info_elements_on(st, t_list); - st->print_cr("}"); - } - } - if (!EnableThreadSMRStatistics) { - return; - } - st->print_cr("_smr_java_thread_list_alloc_cnt=" UINT64_FORMAT "," - "_smr_java_thread_list_free_cnt=" UINT64_FORMAT "," - "_smr_java_thread_list_max=%u, " - "_smr_nested_thread_list_max=%u", - _smr_java_thread_list_alloc_cnt, - _smr_java_thread_list_free_cnt, - _smr_java_thread_list_max, - _smr_nested_thread_list_max); - if (_smr_tlh_cnt > 0) { - st->print_cr("_smr_tlh_cnt=%u" - ", _smr_tlh_times=%u" - ", avg_smr_tlh_time=%0.2f" - ", _smr_tlh_time_max=%u", - _smr_tlh_cnt, _smr_tlh_times, - ((double) _smr_tlh_times / _smr_tlh_cnt), - _smr_tlh_time_max); - } - if (_smr_deleted_thread_cnt > 0) { - st->print_cr("_smr_deleted_thread_cnt=%u" - ", _smr_deleted_thread_times=%u" - ", avg_smr_deleted_thread_time=%0.2f" - ", _smr_deleted_thread_time_max=%u", - _smr_deleted_thread_cnt, _smr_deleted_thread_times, - ((double) _smr_deleted_thread_times / _smr_deleted_thread_cnt), - _smr_deleted_thread_time_max); - } - st->print_cr("_smr_delete_lock_wait_cnt=%u, _smr_delete_lock_wait_max=%u", - _smr_delete_lock_wait_cnt, _smr_delete_lock_wait_max); - st->print_cr("_smr_to_delete_list_cnt=%u, _smr_to_delete_list_max=%u", - _smr_to_delete_list_cnt, _smr_to_delete_list_max); - } - - // Print ThreadsList elements (4 per line). - void Threads::print_smr_info_elements_on(outputStream* st, - ThreadsList* t_list) { - uint cnt = 0; - JavaThreadIterator jti(t_list); - for (JavaThread *jt = jti.first(); jt != NULL; jt = jti.next()) { - st->print(INTPTR_FORMAT, p2i(jt)); - if (cnt < t_list->length() - 1) { - // Separate with comma or comma-space except for the last one. - if (((cnt + 1) % 4) == 0) { - // Four INTPTR_FORMAT fit on an 80 column line so end the - // current line with just a comma. - st->print_cr(","); - } else { - // Not the last one on the current line so use comma-space: - st->print(", "); - } - } else { - // Last one so just end the current line. - st->cr(); - } - cnt++; - } - } - void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, int buflen, bool* found_current) { if (this_thread != NULL) { bool is_current = (current == this_thread); *found_current = *found_current || is_current; --- 4660,4669 ----
*** 5615,5625 **** // that VM is not at safepoint and/or current thread is inside signal handler. // Don't print stack trace, as the stack may not be walkable. Don't allocate // memory (even in resource area), it might deadlock the error handler. void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) { ! print_smr_info_on(st); st->cr(); bool found_current = false; st->print_cr("Java Threads: ( => current thread )"); ALL_JAVA_THREADS(thread) { --- 4696,4706 ---- // that VM is not at safepoint and/or current thread is inside signal handler. // Don't print stack trace, as the stack may not be walkable. Don't allocate // memory (even in resource area), it might deadlock the error handler. void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) { ! ThreadsSMRSupport::print_smr_info_on(st); st->cr(); bool found_current = false; st->print_cr("Java Threads: ( => current thread )"); ALL_JAVA_THREADS(thread) {
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