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src/hotspot/share/runtime/thread.cpp
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rev 47862 : imported patch 10.07.open.rebase_20171110.dcubed
rev 47863 : imported patch 10.08.open.rebase_20171114.rehn
rev 47864 : imported patch 10.09.open.TLH_hang_fix.rehn
rev 47865 : dholmes CR: Fix indents, trailing spaces and various typos. Add descriptions for the '_cnt', '_max' and '_times" fields, add impl notes to document the type choices.
rev 47866 : robinw CR: Fix some inefficient code, update some comments, fix some indents, and add some 'const' specifiers.
*** 69,93 ****
#include "runtime/init.hpp"
#include "runtime/interfaceSupport.hpp"
#include "runtime/java.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/jniPeriodicChecker.hpp"
- #include "runtime/timerTrace.hpp"
#include "runtime/memprofiler.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/objectMonitor.hpp"
#include "runtime/orderAccess.inline.hpp"
#include "runtime/osThread.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/safepointMechanism.inline.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/statSampler.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/sweeper.hpp"
#include "runtime/task.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/threadCritical.hpp"
#include "runtime/vframe.hpp"
#include "runtime/vframeArray.hpp"
#include "runtime/vframe_hp.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vm_operations.hpp"
--- 69,96 ----
#include "runtime/init.hpp"
#include "runtime/interfaceSupport.hpp"
#include "runtime/java.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/jniPeriodicChecker.hpp"
#include "runtime/memprofiler.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/objectMonitor.hpp"
#include "runtime/orderAccess.inline.hpp"
#include "runtime/osThread.hpp"
+ #include "runtime/prefetch.inline.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/safepointMechanism.inline.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/statSampler.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/sweeper.hpp"
#include "runtime/task.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/threadCritical.hpp"
+ #include "runtime/threadSMR.inline.hpp"
+ #include "runtime/timer.hpp"
+ #include "runtime/timerTrace.hpp"
#include "runtime/vframe.hpp"
#include "runtime/vframeArray.hpp"
#include "runtime/vframe_hp.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vm_operations.hpp"
*** 102,111 ****
--- 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"
*** 193,209 ****
}
}
void Thread::operator delete(void* p) {
if (UseBiasedLocking) {
! void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
! FreeHeap(real_malloc_addr);
} else {
FreeHeap(p);
}
}
// Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
// JavaThread
--- 197,219 ----
}
}
void Thread::operator delete(void* p) {
if (UseBiasedLocking) {
! FreeHeap(((Thread*) p)->_real_malloc_address);
} else {
FreeHeap(p);
}
}
+ void JavaThread::smr_delete() {
+ if (_on_thread_list) {
+ Threads::smr_delete(this);
+ } else {
+ delete this;
+ }
+ }
// Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
// JavaThread
*** 225,234 ****
--- 235,247 ----
set_free_handle_block(NULL);
set_last_handle_mark(NULL);
// This initial value ==> never claimed.
_oops_do_parity = 0;
+ _threads_hazard_ptr = NULL;
+ _nested_threads_hazard_ptr = NULL;
+ _nested_threads_hazard_ptr_cnt = 0;
// the handle mark links itself to last_handle_mark
new HandleMark(this);
// plain initialization
*** 396,408 ****
void Thread::run() {
ShouldNotReachHere();
}
#ifdef ASSERT
! // Private method to check for dangling thread pointer
! void check_for_dangling_thread_pointer(Thread *thread) {
! assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
"possibility of dangling Thread pointer");
}
#endif
ThreadPriority Thread::get_priority(const Thread* const thread) {
--- 409,427 ----
void Thread::run() {
ShouldNotReachHere();
}
#ifdef ASSERT
! // A JavaThread is considered "dangling" if it is not the current
! // thread, has been added the Threads list, the system is not at a
! // safepoint and the Thread is not "protected".
! //
! 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) {
*** 730,739 ****
--- 749,789 ----
// thread did not suspend after all our retries
*bits |= 0x00200000;
return false;
}
+ // Called from API entry points which perform stack walking. If the
+ // associated JavaThread is the current thread, then wait_for_suspend
+ // is not used. Otherwise, it determines if we should wait for the
+ // "other" thread to complete external suspension. (NOTE: in future
+ // releases the suspension mechanism should be reimplemented so this
+ // is not necessary.)
+ //
+ bool
+ JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) {
+ if (this != JavaThread::current()) {
+ // "other" threads require special handling.
+ if (wait_for_suspend) {
+ // We are allowed to wait for the external suspend to complete
+ // so give the other thread a chance to get suspended.
+ if (!wait_for_ext_suspend_completion(SuspendRetryCount,
+ SuspendRetryDelay, bits)) {
+ // Didn't make it so let the caller know.
+ return false;
+ }
+ }
+ // We aren't allowed to wait for the external suspend to complete
+ // so if the other thread isn't externally suspended we need to
+ // let the caller know.
+ else if (!is_ext_suspend_completed_with_lock(bits)) {
+ return false;
+ }
+ }
+
+ return true;
+ }
+
#ifndef PRODUCT
void JavaThread::record_jump(address target, address instr, const char* file,
int line) {
// This should not need to be atomic as the only way for simultaneous
*** 808,820 ****
--- 858,894 ----
}
st->print("tid=" INTPTR_FORMAT " ", p2i(this));
ext().print_on(st);
osthread()->print_on(st);
}
+ if (_threads_hazard_ptr != NULL) {
+ st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
+ }
+ if (_nested_threads_hazard_ptr != NULL) {
+ print_nested_threads_hazard_ptrs_on(st);
+ }
+ st->print(" ");
debug_only(if (WizardMode) print_owned_locks_on(st);)
}
+ void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const {
+ assert(_nested_threads_hazard_ptr != NULL, "must be set to print");
+
+ if (EnableThreadSMRStatistics) {
+ st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt);
+ }
+ st->print(", _nested_threads_hazard_ptrs=");
+ for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL;
+ node = node->next()) {
+ if (node != _nested_threads_hazard_ptr) {
+ // First node does not need a comma-space separator.
+ st->print(", ");
+ }
+ st->print(INTPTR_FORMAT, p2i(node->t_list()));
+ }
+ }
+
// Thread::print_on_error() is called by fatal error handler. Don't use
// any lock or allocate memory.
void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates");
*** 832,841 ****
--- 906,922 ----
p2i(stack_end()), p2i(stack_base()));
if (osthread()) {
st->print(" [id=%d]", osthread()->thread_id());
}
+
+ if (_threads_hazard_ptr != NULL) {
+ st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
+ }
+ if (_nested_threads_hazard_ptr != NULL) {
+ print_nested_threads_hazard_ptrs_on(st);
+ }
}
void Thread::print_value_on(outputStream* st) const {
if (is_Named_thread()) {
st->print(" \"%s\" ", name());
*** 869,880 ****
#endif
#ifndef PRODUCT
! // The flag: potential_vm_operation notifies if this particular safepoint state could potential
! // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
// no threads which allow_vm_block's are held
void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
// Check if current thread is allowed to block at a safepoint
if (!(_allow_safepoint_count == 0)) {
fatal("Possible safepoint reached by thread that does not allow it");
--- 950,961 ----
#endif
#ifndef PRODUCT
! // The flag: potential_vm_operation notifies if this particular safepoint state could potentially
! // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that
// no threads which allow_vm_block's are held
void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
// Check if current thread is allowed to block at a safepoint
if (!(_allow_safepoint_count == 0)) {
fatal("Possible safepoint reached by thread that does not allow it");
*** 1396,1410 ****
return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
}
void JavaThread::collect_counters(typeArrayOop array) {
if (JVMCICounterSize > 0) {
MutexLocker tl(Threads_lock);
for (int i = 0; i < array->length(); i++) {
array->long_at_put(i, _jvmci_old_thread_counters[i]);
}
! for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) {
if (jvmci_counters_include(tp)) {
for (int i = 0; i < array->length(); i++) {
array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
}
}
--- 1477,1494 ----
return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread();
}
void JavaThread::collect_counters(typeArrayOop array) {
if (JVMCICounterSize > 0) {
+ // dcubed - Looks like the Threads_lock is for stable access
+ // to _jvmci_old_thread_counters and _jvmci_counters.
MutexLocker tl(Threads_lock);
+ JavaThreadIteratorWithHandle jtiwh;
for (int i = 0; i < array->length(); i++) {
array->long_at_put(i, _jvmci_old_thread_counters[i]);
}
! for (; JavaThread *tp = jtiwh.next(); ) {
if (jvmci_counters_include(tp)) {
for (int i = 0; i < array->length(); i++) {
array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]);
}
}
*** 1433,1442 ****
--- 1517,1527 ----
set_deopt_mark(NULL);
set_deopt_compiled_method(NULL);
clear_must_deopt_id();
set_monitor_chunks(NULL);
set_next(NULL);
+ _on_thread_list = false;
set_thread_state(_thread_new);
_terminated = _not_terminated;
_privileged_stack_top = NULL;
_array_for_gc = NULL;
_suspend_equivalent = false;
*** 1713,1728 ****
}
DTRACE_THREAD_PROBE(stop, this);
this->exit(false);
! delete this;
}
static void ensure_join(JavaThread* thread) {
! // We do not need to grap the Threads_lock, since we are operating on ourself.
Handle threadObj(thread, thread->threadObj());
assert(threadObj.not_null(), "java thread object must exist");
ObjectLocker lock(threadObj, thread);
// Ignore pending exception (ThreadDeath), since we are exiting anyway
thread->clear_pending_exception();
--- 1798,1813 ----
}
DTRACE_THREAD_PROBE(stop, this);
this->exit(false);
! this->smr_delete();
}
static void ensure_join(JavaThread* thread) {
! // We do not need to grab the Threads_lock, since we are operating on ourself.
Handle threadObj(thread, thread->threadObj());
assert(threadObj.not_null(), "java thread object must exist");
ObjectLocker lock(threadObj, thread);
// Ignore pending exception (ThreadDeath), since we are exiting anyway
thread->clear_pending_exception();
*** 1740,1749 ****
--- 1825,1843 ----
// For any new cleanup additions, please check to see if they need to be applied to
// cleanup_failed_attach_current_thread as well.
void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
assert(this == JavaThread::current(), "thread consistency check");
+ elapsedTimer _timer_exit_phase1;
+ elapsedTimer _timer_exit_phase2;
+ elapsedTimer _timer_exit_phase3;
+ elapsedTimer _timer_exit_phase4;
+
+ if (log_is_enabled(Debug, os, thread, timer)) {
+ _timer_exit_phase1.start();
+ }
+
HandleMark hm(this);
Handle uncaught_exception(this, this->pending_exception());
this->clear_pending_exception();
Handle threadObj(this, this->threadObj());
assert(threadObj.not_null(), "Java thread object should be created");
*** 1839,1854 ****
--- 1933,1956 ----
// no more external suspends are allowed at this point
} else {
// before_exit() has already posted JVMTI THREAD_END events
}
+ if (log_is_enabled(Debug, os, thread, timer)) {
+ _timer_exit_phase1.stop();
+ _timer_exit_phase2.start();
+ }
// Notify waiters on thread object. This has to be done after exit() is called
// on the thread (if the thread is the last thread in a daemon ThreadGroup the
// group should have the destroyed bit set before waiters are notified).
ensure_join(this);
assert(!this->has_pending_exception(), "ensure_join should have cleared");
+ if (log_is_enabled(Debug, os, thread, timer)) {
+ _timer_exit_phase2.stop();
+ _timer_exit_phase3.start();
+ }
// 6282335 JNI DetachCurrentThread spec states that all Java monitors
// held by this thread must be released. The spec does not distinguish
// between JNI-acquired and regular Java monitors. We can only see
// regular Java monitors here if monitor enter-exit matching is broken.
//
*** 1912,1927 ****
log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
os::current_thread_id());
// Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
Threads::remove(this);
! // If someone set a handshake on us just as we entered exit path, we simple cancel it.
! if (ThreadLocalHandshakes) {
! cancel_handshake();
}
}
#if INCLUDE_ALL_GCS
// Flush G1-related queues.
--- 2014,2043 ----
log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").",
exit_type == JavaThread::normal_exit ? "exiting" : "detaching",
os::current_thread_id());
+ if (log_is_enabled(Debug, os, thread, timer)) {
+ _timer_exit_phase3.stop();
+ _timer_exit_phase4.start();
+ }
// Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
Threads::remove(this);
! if (log_is_enabled(Debug, os, thread, timer)) {
! _timer_exit_phase4.stop();
! ResourceMark rm(this);
! log_debug(os, thread, timer)("name='%s'"
! ", exit-phase1=" JLONG_FORMAT
! ", exit-phase2=" JLONG_FORMAT
! ", exit-phase3=" JLONG_FORMAT
! ", exit-phase4=" JLONG_FORMAT,
! get_thread_name(),
! _timer_exit_phase1.milliseconds(),
! _timer_exit_phase2.milliseconds(),
! _timer_exit_phase3.milliseconds(),
! _timer_exit_phase4.milliseconds());
}
}
#if INCLUDE_ALL_GCS
// Flush G1-related queues.
*** 1978,1988 ****
flush_barrier_queues();
}
#endif // INCLUDE_ALL_GCS
Threads::remove(this);
! delete this;
}
--- 2094,2104 ----
flush_barrier_queues();
}
#endif // INCLUDE_ALL_GCS
Threads::remove(this);
! this->smr_delete();
}
*** 2233,2247 ****
// + Target thread will not execute any new bytecode (that's why we need to
// force a safepoint)
// + Target thread will not enter any new monitors
//
void JavaThread::java_suspend() {
! { MutexLocker mu(Threads_lock);
! if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
return;
}
- }
{ MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
if (!is_external_suspend()) {
// a racing resume has cancelled us; bail out now
return;
--- 2349,2362 ----
// + Target thread will not execute any new bytecode (that's why we need to
// force a safepoint)
// + Target thread will not enter any new monitors
//
void JavaThread::java_suspend() {
! ThreadsListHandle tlh;
! if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) {
return;
}
{ MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
if (!is_external_suspend()) {
// a racing resume has cancelled us; bail out now
return;
*** 2325,2342 ****
#ifdef ASSERT
// verify the JavaThread has not yet been published in the Threads::list, and
// hence doesn't need protection from concurrent access at this stage
void JavaThread::verify_not_published() {
! if (!Threads_lock->owned_by_self()) {
! MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
! assert(!Threads::includes(this),
! "java thread shouldn't have been published yet!");
! } else {
! assert(!Threads::includes(this),
! "java thread shouldn't have been published yet!");
! }
}
#endif
// Slow path when the native==>VM/Java barriers detect a safepoint is in
// progress or when _suspend_flags is non-zero.
--- 2440,2451 ----
#ifdef ASSERT
// verify the JavaThread has not yet been published in the Threads::list, and
// hence doesn't need protection from concurrent access at this stage
void JavaThread::verify_not_published() {
! ThreadsListHandle tlh;
! assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!");
}
#endif
// Slow path when the native==>VM/Java barriers detect a safepoint is in
// progress or when _suspend_flags is non-zero.
*** 2449,2459 ****
void JavaThread::java_resume() {
assert_locked_or_safepoint(Threads_lock);
// Sanity check: thread is gone, has started exiting or the thread
// was not externally suspended.
! if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
return;
}
MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
--- 2558,2569 ----
void JavaThread::java_resume() {
assert_locked_or_safepoint(Threads_lock);
// Sanity check: thread is gone, has started exiting or the thread
// was not externally suspended.
! ThreadsListHandle tlh;
! if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) {
return;
}
MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
*** 2917,2926 ****
--- 3027,3043 ----
st->print(", id=%d", osthread()->thread_id());
}
st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
p2i(stack_end()), p2i(stack_base()));
st->print("]");
+
+ if (_threads_hazard_ptr != NULL) {
+ st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr));
+ }
+ if (_nested_threads_hazard_ptr != NULL) {
+ print_nested_threads_hazard_ptrs_on(st);
+ }
return;
}
// Verification
*** 3310,3336 ****
// ======= Threads ========
// The Threads class links together all active threads, and provides
! // operations over all threads. It is protected by its own Mutex
! // lock, which is also used in other contexts to protect thread
! // operations from having the thread being operated on from exiting
! // and going away unexpectedly (e.g., safepoint synchronization)
JavaThread* Threads::_thread_list = NULL;
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;
#ifdef ASSERT
bool Threads::_vm_complete = false;
#endif
// All JavaThreads
! #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
// 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
--- 3427,3566 ----
// ======= Threads ========
// The Threads class links together all active threads, and provides
! // operations over all threads. It is protected by the Threads_lock,
! // which is also used in other global contexts like safepointing.
! // ThreadsListHandles are used to safely perform operations on one
! // or more threads without the risk of the thread exiting during the
! // operation.
! //
! // Note: The Threads_lock is currently more widely used than we
! // would like. We are actively migrating Threads_lock uses to other
! // mechanisms in order to reduce Threads_lock contention.
JavaThread* Threads::_thread_list = NULL;
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
+ static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) {
+ Prefetch::read((void*)addr, prefetch_interval);
+ return *addr;
+ }
+
+ // Possibly the ugliest for loop the world has seen. C++ does not allow
+ // multiple types in the declaration section of the for loop. In this case
+ // we are only dealing with pointers and hence can cast them. It looks ugly
+ // but macros are ugly and therefore it's fine to make things absurdly ugly.
+ #define DO_JAVA_THREADS(LIST, X) \
+ for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \
+ *MACRO_list = (JavaThread*)(LIST), \
+ **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \
+ **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \
+ *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(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
*** 3427,3436 ****
--- 3657,3874 ----
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();
+ }
+
+ // 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);
+ }
+ }
+
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();
*** 3608,3618 ****
main_thread->set_active_handles(JNIHandleBlock::allocate_block());
if (!main_thread->set_as_starting_thread()) {
vm_shutdown_during_initialization(
"Failed necessary internal allocation. Out of swap space");
! delete main_thread;
*canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
return JNI_ENOMEM;
}
// Enable guard page *after* os::create_main_thread(), otherwise it would
--- 4046,4056 ----
main_thread->set_active_handles(JNIHandleBlock::allocate_block());
if (!main_thread->set_as_starting_thread()) {
vm_shutdown_during_initialization(
"Failed necessary internal allocation. Out of swap space");
! main_thread->smr_delete();
*canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
return JNI_ENOMEM;
}
// Enable guard page *after* os::create_main_thread(), otherwise it would
*** 3623,3633 ****
ObjectMonitor::Initialize();
// Initialize global modules
jint status = init_globals();
if (status != JNI_OK) {
! delete main_thread;
*canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
return status;
}
if (TRACE_INITIALIZE() != JNI_OK) {
--- 4061,4071 ----
ObjectMonitor::Initialize();
// Initialize global modules
jint status = init_globals();
if (status != JNI_OK) {
! main_thread->smr_delete();
*canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
return status;
}
if (TRACE_INITIALIZE() != JNI_OK) {
*** 4029,4056 ****
vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
}
}
}
- JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
- assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
- JavaThread* java_thread = NULL;
- // Sequential search for now. Need to do better optimization later.
- for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
- oop tobj = thread->threadObj();
- if (!thread->is_exiting() &&
- tobj != NULL &&
- java_tid == java_lang_Thread::thread_id(tobj)) {
- java_thread = thread;
- break;
- }
- }
- return java_thread;
- }
-
-
// Last thread running calls java.lang.Shutdown.shutdown()
void JavaThread::invoke_shutdown_hooks() {
HandleMark hm(this);
// We could get here with a pending exception, if so clear it now.
--- 4467,4477 ----
*** 4171,4180 ****
--- 4592,4606 ----
VM_Exit::set_vm_exited();
notify_vm_shutdown();
+ // We are after VM_Exit::set_vm_exited() so we can't call
+ // thread->smr_delete() or we will block on the Threads_lock.
+ // Deleting the shutdown thread here is safe because another
+ // JavaThread cannot have an active ThreadsListHandle for
+ // this JavaThread.
delete thread;
#if INCLUDE_JVMCI
if (JVMCICounterSize > 0) {
FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters);
*** 4204,4223 ****
--- 4630,5148 ----
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) {
+ 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);
// See the comment for this method in thread.hpp for its purpose and
// why it is called here.
p->initialize_queues();
p->set_next(_thread_list);
_thread_list = p;
+
+ // Once a JavaThread is added to the Threads list, smr_delete() has
+ // to be used to delete it. Otherwise we can just delete it directly.
+ p->set_on_thread_list();
+
_number_of_threads++;
oop threadObj = p->threadObj();
bool daemon = true;
// Bootstrapping problem: threadObj can be null for initial
// JavaThread (or for threads attached via JNI)
*** 4226,4235 ****
--- 5151,5174 ----
daemon = false;
}
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));
}
void Threads::remove(JavaThread* p) {
*** 4239,4250 ****
// 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(includes(p), "p must be present");
JavaThread* current = _thread_list;
JavaThread* prev = NULL;
while (current != p) {
prev = current;
--- 5178,5202 ----
// 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) {
prev = current;
*** 4254,4263 ****
--- 5206,5216 ----
if (prev) {
prev->set_next(current->next());
} else {
_thread_list = p->next();
}
+
_number_of_threads--;
oop threadObj = p->threadObj();
bool daemon = true;
if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
_number_of_non_daemon_threads--;
*** 4280,4300 ****
// Since Events::log uses a lock, we grab it outside the Threads_lock
Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p));
}
- // Threads_lock must be held when this is called (or must be called during a safepoint)
- bool Threads::includes(JavaThread* p) {
- assert(Threads_lock->is_locked(), "sanity check");
- ALL_JAVA_THREADS(q) {
- if (q == p) {
- return true;
- }
- }
- return false;
- }
-
// Operations on the Threads list for GC. These are not explicitly locked,
// but the garbage collector must provide a safe context for them to run.
// In particular, these things should never be called when the Threads_lock
// is held by some other thread. (Note: the Safepoint abstraction also
// uses the Threads_lock to guarantee this property. It also makes sure that
--- 5233,5242 ----
*** 4403,4453 ****
}
}
// Get count Java threads that are waiting to enter the specified monitor.
! GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
! address monitor,
! bool doLock) {
! assert(doLock || SafepointSynchronize::is_at_safepoint(),
! "must grab Threads_lock or be at safepoint");
GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
int i = 0;
! {
! MutexLockerEx ml(doLock ? Threads_lock : NULL);
! ALL_JAVA_THREADS(p) {
if (!p->can_call_java()) continue;
address pending = (address)p->current_pending_monitor();
if (pending == monitor) { // found a match
if (i < count) result->append(p); // save the first count matches
i++;
}
}
! }
return result;
}
! JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
! bool doLock) {
! assert(doLock ||
! Threads_lock->owned_by_self() ||
! SafepointSynchronize::is_at_safepoint(),
! "must grab Threads_lock or be at safepoint");
!
// NULL owner means not locked so we can skip the search
if (owner == NULL) return NULL;
! {
! MutexLockerEx ml(doLock ? Threads_lock : NULL);
! ALL_JAVA_THREADS(p) {
// first, see if owner is the address of a Java thread
if (owner == (address)p) return p;
}
! }
// Cannot assert on lack of success here since this function may be
// used by code that is trying to report useful problem information
// like deadlock detection.
if (UseHeavyMonitors) return NULL;
--- 5345,5384 ----
}
}
// Get count Java threads that are waiting to enter the specified monitor.
! GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list,
! int count,
! address monitor) {
GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
int i = 0;
! DO_JAVA_THREADS(t_list, p) {
if (!p->can_call_java()) continue;
address pending = (address)p->current_pending_monitor();
if (pending == monitor) { // found a match
if (i < count) result->append(p); // save the first count matches
i++;
}
}
!
return result;
}
! JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list,
! address owner) {
// NULL owner means not locked so we can skip the search
if (owner == NULL) return NULL;
! DO_JAVA_THREADS(t_list, p) {
// first, see if owner is the address of a Java thread
if (owner == (address)p) return p;
}
!
// Cannot assert on lack of success here since this function may be
// used by code that is trying to report useful problem information
// like deadlock detection.
if (UseHeavyMonitors) return NULL;
*** 4454,4472 ****
// If we didn't find a matching Java thread and we didn't force use of
// heavyweight monitors, then the owner is the stack address of the
// Lock Word in the owning Java thread's stack.
//
JavaThread* the_owner = NULL;
! {
! MutexLockerEx ml(doLock ? Threads_lock : NULL);
! ALL_JAVA_THREADS(q) {
if (q->is_lock_owned(owner)) {
the_owner = q;
break;
}
}
! }
// cannot assert on lack of success here; see above comment
return the_owner;
}
// Threads::print_on() is called at safepoint by VM_PrintThreads operation.
--- 5385,5401 ----
// If we didn't find a matching Java thread and we didn't force use of
// heavyweight monitors, then the owner is the stack address of the
// Lock Word in the owning Java thread's stack.
//
JavaThread* the_owner = NULL;
! DO_JAVA_THREADS(t_list, q) {
if (q->is_lock_owned(owner)) {
the_owner = q;
break;
}
}
!
// cannot assert on lack of success here; see above comment
return the_owner;
}
// Threads::print_on() is called at safepoint by VM_PrintThreads operation.
*** 4487,4496 ****
--- 5416,5428 ----
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);
if (print_stacks) {
if (internal_format) {
*** 4513,4525 ****
--- 5445,5553 ----
WatcherThread* wt = WatcherThread::watcher_thread();
if (wt != NULL) {
wt->print_on(st);
st->cr();
}
+
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;
*** 4552,4561 ****
--- 5580,5592 ----
// 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) {
print_on_error(thread, st, current, buf, buflen, &found_current);
}
*** 4573,4582 ****
--- 5604,5614 ----
st->print("=>" PTR_FORMAT " (exited) ", p2i(current));
current->print_on_error(st, buf, buflen);
st->cr();
}
st->cr();
+
st->print_cr("Threads with active compile tasks:");
print_threads_compiling(st, buf, buflen);
}
void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) {
< prev index next >