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src/hotspot/share/runtime/thread.cpp
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rev 48162 : 8191789: migrate more Thread-SMR stuff from thread.[ch]pp -> threadSMR.[ch]pp
Reviewed-by: stefank
rev 48163 : CR round 0: dcubed - move more code into sort order, add update_smr_tlh_stats(); stefank - refactor Threads::add() and Threads::remove() to allow more ThreadsSMRSupport functions to be private, move is_a_protected_JavaThread_with_lock() to threadSMR.inline.hpp
@@ -105,11 +105,10 @@
#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"
@@ -205,11 +204,11 @@
}
}
void JavaThread::smr_delete() {
if (_on_thread_list) {
- Threads::smr_delete(this);
+ ThreadsSMRSupport::smr_delete(this);
} else {
delete this;
}
}
@@ -417,11 +416,11 @@
//
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),
+ ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread),
"possibility of dangling Thread pointer");
}
#endif
ThreadPriority Thread::get_priority(const Thread* const thread) {
@@ -3447,98 +3446,10 @@
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
@@ -3559,16 +3470,12 @@
*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)
+#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
@@ -3665,244 +3572,10 @@
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();
@@ -4664,505 +4337,10 @@
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);
@@ -5187,22 +4365,11 @@
}
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);
+ ThreadsSMRSupport::add_thread(p);
// Possible GC point.
Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p));
}
@@ -5213,24 +4380,14 @@
// 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");
+ assert(ThreadsSMRSupport::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);
+ ThreadsSMRSupport::remove_thread(p);
JavaThread* current = _thread_list;
JavaThread* prev = NULL;
while (current != p) {
@@ -5451,11 +4608,11 @@
if (print_concurrent_locks) {
concurrent_locks.dump_at_safepoint();
}
#endif // INCLUDE_SERVICES
- print_smr_info_on(st);
+ ThreadsSMRSupport::print_smr_info_on(st);
st->cr();
ALL_JAVA_THREADS(p) {
ResourceMark rm;
p->print_on(st);
@@ -5484,105 +4641,10 @@
}
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;
@@ -5615,11 +4677,11 @@
// 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);
+ 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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