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6900441: PlatformEvent.park(millis) on Linux could still be affected by changes to the time-of-day clock

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Associate CLOCK_MONOTONIC with the pthread_cond_t objects used for relative timed waits

Reviewed-by: dcubed, shade
This commit is contained in:
David Holmes 2013-09-16 07:38:13 -04:00
parent 59a89ae1e1
commit 139c3e6621
2 changed files with 128 additions and 45 deletions
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148
hotspot/src/os/linux/vm/os_linux.cpp
View file

@ -131,6 +131,7 @@ bool os::Linux::_is_NPTL = false;
bool os::Linux::_supports_fast_thread_cpu_time = false;
const char * os::Linux::_glibc_version = NULL;
const char * os::Linux::_libpthread_version = NULL;
pthread_condattr_t os::Linux::_condattr[1];
static jlong initial_time_count=0;
@ -1399,12 +1400,15 @@ void os::Linux::clock_init() {
clock_gettime_func(CLOCK_MONOTONIC, &tp) == 0) {
// yes, monotonic clock is supported
_clock_gettime = clock_gettime_func;
return;
} else {
// close librt if there is no monotonic clock
dlclose(handle);
}
}
}
warning("No monotonic clock was available - timed services may " \
"be adversely affected if the time-of-day clock changes");
}
#ifndef SYS_clock_getres
@ -4709,6 +4713,26 @@ void os::init(void) {
Linux::clock_init();
initial_time_count = os::elapsed_counter();
// pthread_condattr initialization for monotonic clock
int status;
pthread_condattr_t* _condattr = os::Linux::condAttr();
if ((status = pthread_condattr_init(_condattr)) != 0) {
fatal(err_msg("pthread_condattr_init: %s", strerror(status)));
}
// Only set the clock if CLOCK_MONOTONIC is available
if (Linux::supports_monotonic_clock()) {
if ((status = pthread_condattr_setclock(_condattr, CLOCK_MONOTONIC)) != 0) {
if (status == EINVAL) {
warning("Unable to use monotonic clock with relative timed-waits" \
" - changes to the time-of-day clock may have adverse affects");
} else {
fatal(err_msg("pthread_condattr_setclock: %s", strerror(status)));
}
}
}
// else it defaults to CLOCK_REALTIME
pthread_mutex_init(&dl_mutex, NULL);
// If the pagesize of the VM is greater than 8K determine the appropriate
@ -5519,21 +5543,36 @@ void os::pause() {
static struct timespec* compute_abstime(timespec* abstime, jlong millis) {
if (millis < 0) millis = 0;
struct timeval now;
int status = gettimeofday(&now, NULL);
assert(status == 0, "gettimeofday");
jlong seconds = millis / 1000;
millis %= 1000;
if (seconds > 50000000) { // see man cond_timedwait(3T)
seconds = 50000000;
}
abstime->tv_sec = now.tv_sec + seconds;
long usec = now.tv_usec + millis * 1000;
if (usec >= 1000000) {
abstime->tv_sec += 1;
usec -= 1000000;
if (os::Linux::supports_monotonic_clock()) {
struct timespec now;
int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
assert_status(status == 0, status, "clock_gettime");
abstime->tv_sec = now.tv_sec + seconds;
long nanos = now.tv_nsec + millis * NANOSECS_PER_MILLISEC;
if (nanos >= NANOSECS_PER_SEC) {
abstime->tv_sec += 1;
nanos -= NANOSECS_PER_SEC;
}
abstime->tv_nsec = nanos;
} else {
struct timeval now;
int status = gettimeofday(&now, NULL);
assert(status == 0, "gettimeofday");
abstime->tv_sec = now.tv_sec + seconds;
long usec = now.tv_usec + millis * 1000;
if (usec >= 1000000) {
abstime->tv_sec += 1;
usec -= 1000000;
}
abstime->tv_nsec = usec * 1000;
}
abstime->tv_nsec = usec * 1000;
return abstime;
}
@ -5625,7 +5664,7 @@ int os::PlatformEvent::park(jlong millis) {
status = os::Linux::safe_cond_timedwait(_cond, _mutex, &abst);
if (status != 0 && WorkAroundNPTLTimedWaitHang) {
pthread_cond_destroy (_cond);
pthread_cond_init (_cond, NULL) ;
pthread_cond_init (_cond, os::Linux::condAttr()) ;
}
assert_status(status == 0 || status == EINTR ||
status == ETIME || status == ETIMEDOUT,
@ -5726,32 +5765,50 @@ void os::PlatformEvent::unpark() {
static void unpackTime(timespec* absTime, bool isAbsolute, jlong time) {
assert (time > 0, "convertTime");
time_t max_secs = 0;
struct timeval now;
int status = gettimeofday(&now, NULL);
assert(status == 0, "gettimeofday");
if (!os::Linux::supports_monotonic_clock() || isAbsolute) {
struct timeval now;
int status = gettimeofday(&now, NULL);
assert(status == 0, "gettimeofday");
time_t max_secs = now.tv_sec + MAX_SECS;
max_secs = now.tv_sec + MAX_SECS;
if (isAbsolute) {
jlong secs = time / 1000;
if (secs > max_secs) {
absTime->tv_sec = max_secs;
if (isAbsolute) {
jlong secs = time / 1000;
if (secs > max_secs) {
absTime->tv_sec = max_secs;
} else {
absTime->tv_sec = secs;
}
absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
} else {
jlong secs = time / NANOSECS_PER_SEC;
if (secs >= MAX_SECS) {
absTime->tv_sec = max_secs;
absTime->tv_nsec = 0;
} else {
absTime->tv_sec = now.tv_sec + secs;
absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
absTime->tv_nsec -= NANOSECS_PER_SEC;
++absTime->tv_sec; // note: this must be <= max_secs
}
}
}
else {
absTime->tv_sec = secs;
}
absTime->tv_nsec = (time % 1000) * NANOSECS_PER_MILLISEC;
}
else {
} else {
// must be relative using monotonic clock
struct timespec now;
int status = os::Linux::clock_gettime(CLOCK_MONOTONIC, &now);
assert_status(status == 0, status, "clock_gettime");
max_secs = now.tv_sec + MAX_SECS;
jlong secs = time / NANOSECS_PER_SEC;
if (secs >= MAX_SECS) {
absTime->tv_sec = max_secs;
absTime->tv_nsec = 0;
}
else {
} else {
absTime->tv_sec = now.tv_sec + secs;
absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_usec*1000;
absTime->tv_nsec = (time % NANOSECS_PER_SEC) + now.tv_nsec;
if (absTime->tv_nsec >= NANOSECS_PER_SEC) {
absTime->tv_nsec -= NANOSECS_PER_SEC;
++absTime->tv_sec; // note: this must be <= max_secs
@ -5831,15 +5888,19 @@ void Parker::park(bool isAbsolute, jlong time) {
jt->set_suspend_equivalent();
// cleared by handle_special_suspend_equivalent_condition() or java_suspend_self()
assert(_cur_index == -1, "invariant");
if (time == 0) {
status = pthread_cond_wait (_cond, _mutex) ;
_cur_index = REL_INDEX; // arbitrary choice when not timed
status = pthread_cond_wait (&_cond[_cur_index], _mutex) ;
} else {
status = os::Linux::safe_cond_timedwait (_cond, _mutex, &absTime) ;
_cur_index = isAbsolute ? ABS_INDEX : REL_INDEX;
status = os::Linux::safe_cond_timedwait (&_cond[_cur_index], _mutex, &absTime) ;
if (status != 0 && WorkAroundNPTLTimedWaitHang) {
pthread_cond_destroy (_cond) ;
pthread_cond_init (_cond, NULL);
pthread_cond_destroy (&_cond[_cur_index]) ;
pthread_cond_init (&_cond[_cur_index], isAbsolute ? NULL : os::Linux::condAttr());
}
}
_cur_index = -1;
assert_status(status == 0 || status == EINTR ||
status == ETIME || status == ETIMEDOUT,
status, "cond_timedwait");
@ -5868,17 +5929,24 @@ void Parker::unpark() {
s = _counter;
_counter = 1;
if (s < 1) {
if (WorkAroundNPTLTimedWaitHang) {
status = pthread_cond_signal (_cond) ;
assert (status == 0, "invariant") ;
// thread might be parked
if (_cur_index != -1) {
// thread is definitely parked
if (WorkAroundNPTLTimedWaitHang) {
status = pthread_cond_signal (&_cond[_cur_index]);
assert (status == 0, "invariant");
status = pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant") ;
} else {
assert (status == 0, "invariant");
} else {
status = pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant") ;
status = pthread_cond_signal (_cond) ;
assert (status == 0, "invariant") ;
}
assert (status == 0, "invariant");
status = pthread_cond_signal (&_cond[_cur_index]);
assert (status == 0, "invariant");
}
} else {
pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant") ;
}
} else {
pthread_mutex_unlock(_mutex);
assert (status == 0, "invariant") ;