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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.
*** 3427,3469 ****
// ======= 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;
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:
uint Threads::_smr_delete_lock_wait_cnt = 0;
uint Threads::_smr_delete_lock_wait_max = 0;
! volatile jint Threads::_smr_delete_notify = 0;
! volatile jint Threads::_smr_deleted_thread_cnt = 0;
! volatile jint Threads::_smr_deleted_thread_time_max = 0;
! volatile jint Threads::_smr_deleted_thread_times = 0;
ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0);
! long Threads::_smr_java_thread_list_alloc_cnt = 1;
! long Threads::_smr_java_thread_list_free_cnt = 0;
uint Threads::_smr_java_thread_list_max = 0;
uint Threads::_smr_nested_thread_list_max = 0;
! volatile jint Threads::_smr_tlh_cnt = 0;
! volatile jint Threads::_smr_tlh_time_max = 0;
! volatile jint Threads::_smr_tlh_times = 0;
ThreadsList* Threads::_smr_to_delete_list = NULL;
uint Threads::_smr_to_delete_list_cnt = 0;
uint Threads::_smr_to_delete_list_max = 0;
#ifdef ASSERT
bool Threads::_vm_complete = false;
#endif
--- 3427,3539 ----
// ======= 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
*** 4824,4842 ****
Threads::clear_smr_delete_notify();
Threads::smr_delete_lock()->unlock();
// Retry the whole scenario.
}
- // If someone set a handshake on us just as we entered exit path, we simple cancel it.
if (ThreadLocalHandshakes) {
thread->cancel_handshake();
}
delete thread;
if (EnableThreadSMRStatistics) {
timer.stop();
! jint millis = (jint)timer.milliseconds();
Threads::inc_smr_deleted_thread_cnt();
Threads::add_smr_deleted_thread_times(millis);
Threads::update_smr_deleted_thread_time_max(millis);
}
--- 4894,4912 ----
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);
}
*** 5417,5448 ****
}
}
if (!EnableThreadSMRStatistics) {
return;
}
! st->print_cr("_smr_java_thread_list_alloc_cnt=%ld, "
! "_smr_java_thread_list_free_cnt=%ld, "
"_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=" INT32_FORMAT
! ", _smr_tlh_times=" INT32_FORMAT
", avg_smr_tlh_time=%0.2f"
! ", _smr_tlh_time_max=" INT32_FORMAT,
_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=" INT32_FORMAT
! ", _smr_deleted_thread_times=" INT32_FORMAT
", avg_smr_deleted_thread_time=%0.2f"
! ", _smr_deleted_thread_time_max=" INT32_FORMAT,
_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",
--- 5487,5518 ----
}
}
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",
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