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8301229: Clean up SuspendibleThreadSet::_suspend_all

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Reviewed-by: stefank, kbarrett, tschatzl
This commit is contained in:
Erik Österlund 2023-01-30 10:27:40 +00:00
parent f50cda7d45
commit 7fae3a1d8d
2 changed files with 23 additions and 19 deletions
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16
src/hotspot/share/gc/shared/suspendibleThreadSet.cpp
View File

@ -50,7 +50,7 @@ bool SuspendibleThreadSet::is_synchronized() {
void SuspendibleThreadSet::join() { void SuspendibleThreadSet::join() {
assert(!Thread::current()->is_suspendible_thread(), "Thread already joined"); assert(!Thread::current()->is_suspendible_thread(), "Thread already joined");
MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag); MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag);
while (suspend_all()) { while (should_yield()) {
ml.wait(); ml.wait();
} }
_nthreads++; _nthreads++;
@ -63,16 +63,16 @@ void SuspendibleThreadSet::leave() {
assert(_nthreads > 0, "Invalid"); assert(_nthreads > 0, "Invalid");
DEBUG_ONLY(Thread::current()->clear_suspendible_thread();) DEBUG_ONLY(Thread::current()->clear_suspendible_thread();)
_nthreads--; _nthreads--;
if (suspend_all() && is_synchronized()) { if (should_yield() && is_synchronized()) {
// This leave completes a request, so inform the requestor. // This leave completes a request, so inform the requestor.
_synchronize_wakeup->signal(); _synchronize_wakeup->signal();
} }
} }
void SuspendibleThreadSet::yield() { void SuspendibleThreadSet::yield_slow() {
assert(Thread::current()->is_suspendible_thread(), "Must have joined"); assert(Thread::current()->is_suspendible_thread(), "Must have joined");
MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag); MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag);
if (suspend_all()) { if (should_yield()) {
_nthreads_stopped++; _nthreads_stopped++;
if (is_synchronized()) { if (is_synchronized()) {
if (ConcGCYieldTimeout > 0) { if (ConcGCYieldTimeout > 0) {
@ -82,7 +82,7 @@ void SuspendibleThreadSet::yield() {
// This yield completes the request, so inform the requestor. // This yield completes the request, so inform the requestor.
_synchronize_wakeup->signal(); _synchronize_wakeup->signal();
} }
while (suspend_all()) { while (should_yield()) {
ml.wait(); ml.wait();
} }
assert(_nthreads_stopped > 0, "Invalid"); assert(_nthreads_stopped > 0, "Invalid");
@ -97,7 +97,7 @@ void SuspendibleThreadSet::synchronize() {
} }
{ {
MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag); MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag);
assert(!suspend_all(), "Only one at a time"); assert(!should_yield(), "Only one at a time");
Atomic::store(&_suspend_all, true); Atomic::store(&_suspend_all, true);
if (is_synchronized()) { if (is_synchronized()) {
return; return;
@ -120,7 +120,7 @@ void SuspendibleThreadSet::synchronize() {
#ifdef ASSERT #ifdef ASSERT
MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag); MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag);
assert(suspend_all(), "STS not synchronizing"); assert(should_yield(), "STS not synchronizing");
assert(is_synchronized(), "STS not synchronized"); assert(is_synchronized(), "STS not synchronized");
#endif #endif
} }
@ -128,7 +128,7 @@ void SuspendibleThreadSet::synchronize() {
void SuspendibleThreadSet::desynchronize() { void SuspendibleThreadSet::desynchronize() {
assert(Thread::current()->is_VM_thread(), "Must be the VM thread"); assert(Thread::current()->is_VM_thread(), "Must be the VM thread");
MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag); MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag);
assert(suspend_all(), "STS not synchronizing"); assert(should_yield(), "STS not synchronizing");
assert(is_synchronized(), "STS not synchronized"); assert(is_synchronized(), "STS not synchronized");
Atomic::store(&_suspend_all, false); Atomic::store(&_suspend_all, false);
ml.notify_all(); ml.notify_all();

14
src/hotspot/share/gc/shared/suspendibleThreadSet.hpp
View File

@ -41,10 +41,9 @@ class SuspendibleThreadSet : public AllStatic {
friend class SuspendibleThreadSetLeaver; friend class SuspendibleThreadSetLeaver;
private: private:
static volatile bool _suspend_all;
static uint _nthreads; static uint _nthreads;
static uint _nthreads_stopped; static uint _nthreads_stopped;
static volatile bool _suspend_all;
static double _suspend_all_start; static double _suspend_all_start;
static bool is_synchronized(); static bool is_synchronized();
@ -55,14 +54,19 @@ private:
// Removes the current thread from the set. // Removes the current thread from the set.
static void leave(); static void leave();
static bool suspend_all() { return Atomic::load(&_suspend_all); } // Suspends the current thread if a suspension is in progress.
static void yield_slow();
public: public:
// Returns true if an suspension is in progress. // Returns true if an suspension is in progress.
static bool should_yield() { return suspend_all(); } static bool should_yield() { return Atomic::load(&_suspend_all); }
// Suspends the current thread if a suspension is in progress. // Suspends the current thread if a suspension is in progress.
static void yield(); static void yield() {
if (should_yield()) {
yield_slow();
}
}
// Returns when all threads in the set are suspended. // Returns when all threads in the set are suspended.
static void synchronize(); static void synchronize();