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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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24
src/hotspot/share/gc/shared/suspendibleThreadSet.cpp
View File

@ -29,10 +29,10 @@
#include "runtime/mutexLocker.hpp"
#include "runtime/semaphore.hpp"
uint SuspendibleThreadSet::_nthreads = 0;
uint SuspendibleThreadSet::_nthreads_stopped = 0;
volatile bool SuspendibleThreadSet::_suspend_all = false;
double SuspendibleThreadSet::_suspend_all_start = 0.0;
uint SuspendibleThreadSet::_nthreads = 0;
uint SuspendibleThreadSet::_nthreads_stopped = 0;
volatile bool SuspendibleThreadSet::_suspend_all = false;
double SuspendibleThreadSet::_suspend_all_start = 0.0;
static Semaphore* _synchronize_wakeup = NULL;
@ -50,7 +50,7 @@ bool SuspendibleThreadSet::is_synchronized() {
void SuspendibleThreadSet::join() {
assert(!Thread::current()->is_suspendible_thread(), "Thread already joined");
MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag);
while (suspend_all()) {
while (should_yield()) {
ml.wait();
}
_nthreads++;
@ -63,16 +63,16 @@ void SuspendibleThreadSet::leave() {
assert(_nthreads > 0, "Invalid");
DEBUG_ONLY(Thread::current()->clear_suspendible_thread();)
_nthreads--;
if (suspend_all() && is_synchronized()) {
if (should_yield() && is_synchronized()) {
// This leave completes a request, so inform the requestor.
_synchronize_wakeup->signal();
}
}
void SuspendibleThreadSet::yield() {
void SuspendibleThreadSet::yield_slow() {
assert(Thread::current()->is_suspendible_thread(), "Must have joined");
MonitorLocker ml(STS_lock, Mutex::_no_safepoint_check_flag);
if (suspend_all()) {
if (should_yield()) {
_nthreads_stopped++;
if (is_synchronized()) {
if (ConcGCYieldTimeout > 0) {
@ -82,7 +82,7 @@ void SuspendibleThreadSet::yield() {
// This yield completes the request, so inform the requestor.
_synchronize_wakeup->signal();
}
while (suspend_all()) {
while (should_yield()) {
ml.wait();
}
assert(_nthreads_stopped > 0, "Invalid");
@ -97,7 +97,7 @@ void SuspendibleThreadSet::synchronize() {
}
{
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);
if (is_synchronized()) {
return;
@ -120,7 +120,7 @@ void SuspendibleThreadSet::synchronize() {
#ifdef ASSERT
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");
#endif
}
@ -128,7 +128,7 @@ void SuspendibleThreadSet::synchronize() {
void SuspendibleThreadSet::desynchronize() {
assert(Thread::current()->is_VM_thread(), "Must be the VM thread");
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");
Atomic::store(&_suspend_all, false);
ml.notify_all();

18
src/hotspot/share/gc/shared/suspendibleThreadSet.hpp
View File

@ -41,11 +41,10 @@ class SuspendibleThreadSet : public AllStatic {
friend class SuspendibleThreadSetLeaver;
private:
static uint _nthreads;
static uint _nthreads_stopped;
static volatile bool _suspend_all;
static uint _nthreads;
static uint _nthreads_stopped;
static double _suspend_all_start;
static double _suspend_all_start;
static bool is_synchronized();
@ -55,14 +54,19 @@ private:
// Removes the current thread from the set.
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:
// 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.
static void yield();
static void yield() {
if (should_yield()) {
yield_slow();
}
}
// Returns when all threads in the set are suspended.
static void synchronize();