[Python-checkins] bpo-12822: use monotonic clock for condvar if possible (GH-11723)
Inada Naoki
webhook-mailer at python.org
Tue Feb 19 20:00:14 EST 2019
https://github.com/python/cpython/commit/001fee14e0f2ba5f41fb733adc69d5965925a094
commit: 001fee14e0f2ba5f41fb733adc69d5965925a094
branch: master
author: Inada Naoki <methane at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2019-02-20T10:00:09+09:00
summary:
bpo-12822: use monotonic clock for condvar if possible (GH-11723)
files:
A Misc/NEWS.d/next/Core and Builtins/2019-02-05-12-48-23.bpo-12822.0x2NDx.rst
M Makefile.pre.in
M Python/ceval.c
M Python/condvar.h
M Python/thread_pthread.h
M configure
M configure.ac
M pyconfig.h.in
diff --git a/Makefile.pre.in b/Makefile.pre.in
index f8216971958a..1c536f813f8d 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -939,7 +939,8 @@ regen-opcode-targets:
$(srcdir)/Python/opcode_targets.h.new
$(UPDATE_FILE) $(srcdir)/Python/opcode_targets.h $(srcdir)/Python/opcode_targets.h.new
-Python/ceval.o: $(srcdir)/Python/opcode_targets.h $(srcdir)/Python/ceval_gil.h
+Python/ceval.o: $(srcdir)/Python/opcode_targets.h $(srcdir)/Python/ceval_gil.h \
+ $(srcdir)/Python/condvar.h
Python/frozen.o: $(srcdir)/Python/importlib.h $(srcdir)/Python/importlib_external.h \
$(srcdir)/Python/importlib_zipimport.h
@@ -1838,7 +1839,7 @@ patchcheck: @DEF_MAKE_RULE@
# Dependencies
-Python/thread.o: @THREADHEADERS@
+Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
# Declare targets that aren't real files
.PHONY: all build_all sharedmods check-clean-src oldsharedmods test quicktest
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-02-05-12-48-23.bpo-12822.0x2NDx.rst b/Misc/NEWS.d/next/Core and Builtins/2019-02-05-12-48-23.bpo-12822.0x2NDx.rst
new file mode 100644
index 000000000000..a3de435f527e
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-02-05-12-48-23.bpo-12822.0x2NDx.rst
@@ -0,0 +1,2 @@
+Use monotonic clock for ``pthread_cond_timedwait`` when
+``pthread_condattr_setclock`` and ``CLOCK_MONOTONIC`` are available.
diff --git a/Python/ceval.c b/Python/ceval.c
index 3db7c7c92a0e..03456f6d2ab4 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -171,6 +171,7 @@ PyEval_InitThreads(void)
{
if (gil_created())
return;
+ PyThread_init_thread();
create_gil();
take_gil(_PyThreadState_GET());
_PyRuntime.ceval.pending.main_thread = PyThread_get_thread_ident();
diff --git a/Python/condvar.h b/Python/condvar.h
index 13517409aeab..f54adc5ea8e8 100644
--- a/Python/condvar.h
+++ b/Python/condvar.h
@@ -48,19 +48,9 @@
* POSIX support
*/
-#define PyCOND_ADD_MICROSECONDS(tv, interval) \
-do { /* TODO: add overflow and truncation checks */ \
- tv.tv_usec += (long) interval; \
- tv.tv_sec += tv.tv_usec / 1000000; \
- tv.tv_usec %= 1000000; \
-} while (0)
-
-/* We assume all modern POSIX systems have gettimeofday() */
-#ifdef GETTIMEOFDAY_NO_TZ
-#define PyCOND_GETTIMEOFDAY(ptv) gettimeofday(ptv)
-#else
-#define PyCOND_GETTIMEOFDAY(ptv) gettimeofday(ptv, (struct timezone *)NULL)
-#endif
+/* These private functions are implemented in Python/thread_pthread.h */
+int _PyThread_cond_init(PyCOND_T *cond);
+void _PyThread_cond_after(long long us, struct timespec *abs);
/* The following functions return 0 on success, nonzero on error */
#define PyMUTEX_INIT(mut) pthread_mutex_init((mut), NULL)
@@ -68,7 +58,7 @@ do { /* TODO: add overflow and truncation checks */ \
#define PyMUTEX_LOCK(mut) pthread_mutex_lock(mut)
#define PyMUTEX_UNLOCK(mut) pthread_mutex_unlock(mut)
-#define PyCOND_INIT(cond) pthread_cond_init((cond), NULL)
+#define PyCOND_INIT(cond) _PyThread_cond_init(cond)
#define PyCOND_FINI(cond) pthread_cond_destroy(cond)
#define PyCOND_SIGNAL(cond) pthread_cond_signal(cond)
#define PyCOND_BROADCAST(cond) pthread_cond_broadcast(cond)
@@ -78,22 +68,16 @@ do { /* TODO: add overflow and truncation checks */ \
Py_LOCAL_INLINE(int)
PyCOND_TIMEDWAIT(PyCOND_T *cond, PyMUTEX_T *mut, long long us)
{
- int r;
- struct timespec ts;
- struct timeval deadline;
-
- PyCOND_GETTIMEOFDAY(&deadline);
- PyCOND_ADD_MICROSECONDS(deadline, us);
- ts.tv_sec = deadline.tv_sec;
- ts.tv_nsec = deadline.tv_usec * 1000;
-
- r = pthread_cond_timedwait((cond), (mut), &ts);
- if (r == ETIMEDOUT)
+ struct timespec abs;
+ _PyThread_cond_after(us, &abs);
+ int ret = pthread_cond_timedwait(cond, mut, &abs);
+ if (ret == ETIMEDOUT) {
return 1;
- else if (r)
+ }
+ if (ret) {
return -1;
- else
- return 0;
+ }
+ return 0;
}
#elif defined(NT_THREADS)
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 09e53a14aa47..25f58d9446d8 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -56,16 +56,6 @@
#endif
#endif
-#if !defined(pthread_attr_default)
-# define pthread_attr_default ((pthread_attr_t *)NULL)
-#endif
-#if !defined(pthread_mutexattr_default)
-# define pthread_mutexattr_default ((pthread_mutexattr_t *)NULL)
-#endif
-#if !defined(pthread_condattr_default)
-# define pthread_condattr_default ((pthread_condattr_t *)NULL)
-#endif
-
/* Whether or not to use semaphores directly rather than emulating them with
* mutexes and condition variables:
@@ -110,6 +100,56 @@ do { \
} while(0)
+/*
+ * pthread_cond support
+ */
+
+#if defined(HAVE_PTHREAD_CONDATTR_SETCLOCK) && defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
+// monotonic is supported statically. It doesn't mean it works on runtime.
+#define CONDATTR_MONOTONIC
+#endif
+
+// NULL when pthread_condattr_setclock(CLOCK_MONOTONIC) is not supported.
+static pthread_condattr_t *condattr_monotonic = NULL;
+
+static void
+init_condattr()
+{
+#ifdef CONDATTR_MONOTONIC
+ static pthread_condattr_t ca;
+ pthread_condattr_init(&ca);
+ if (pthread_condattr_setclock(&ca, CLOCK_MONOTONIC) == 0) {
+ condattr_monotonic = &ca; // Use monotonic clock
+ }
+#endif
+}
+
+int
+_PyThread_cond_init(PyCOND_T *cond)
+{
+ return pthread_cond_init(cond, condattr_monotonic);
+}
+
+void
+_PyThread_cond_after(long long us, struct timespec *abs)
+{
+#ifdef CONDATTR_MONOTONIC
+ if (condattr_monotonic) {
+ clock_gettime(CLOCK_MONOTONIC, abs);
+ abs->tv_sec += us / 1000000;
+ abs->tv_nsec += (us % 1000000) * 1000;
+ abs->tv_sec += abs->tv_nsec / 1000000000;
+ abs->tv_nsec %= 1000000000;
+ return;
+ }
+#endif
+
+ struct timespec ts;
+ MICROSECONDS_TO_TIMESPEC(us, ts);
+ *abs = ts;
+}
+
+
/* A pthread mutex isn't sufficient to model the Python lock type
* because, according to Draft 5 of the docs (P1003.4a/D5), both of the
* following are undefined:
@@ -146,6 +186,7 @@ PyThread__init_thread(void)
extern void pthread_init(void);
pthread_init();
#endif
+ init_condattr();
}
/*
@@ -462,8 +503,7 @@ PyThread_allocate_lock(void)
memset((void *)lock, '\0', sizeof(pthread_lock));
lock->locked = 0;
- status = pthread_mutex_init(&lock->mut,
- pthread_mutexattr_default);
+ status = pthread_mutex_init(&lock->mut, NULL);
CHECK_STATUS_PTHREAD("pthread_mutex_init");
/* Mark the pthread mutex underlying a Python mutex as
pure happens-before. We can't simply mark the
@@ -472,8 +512,7 @@ PyThread_allocate_lock(void)
will cause errors. */
_Py_ANNOTATE_PURE_HAPPENS_BEFORE_MUTEX(&lock->mut);
- status = pthread_cond_init(&lock->lock_released,
- pthread_condattr_default);
+ status = _PyThread_cond_init(&lock->lock_released);
CHECK_STATUS_PTHREAD("pthread_cond_init");
if (error) {
@@ -532,9 +571,10 @@ PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds,
success = PY_LOCK_ACQUIRED;
}
else if (microseconds != 0) {
- struct timespec ts;
- if (microseconds > 0)
- MICROSECONDS_TO_TIMESPEC(microseconds, ts);
+ struct timespec abs;
+ if (microseconds > 0) {
+ _PyThread_cond_after(microseconds, &abs);
+ }
/* continue trying until we get the lock */
/* mut must be locked by me -- part of the condition
@@ -543,10 +583,13 @@ PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds,
if (microseconds > 0) {
status = pthread_cond_timedwait(
&thelock->lock_released,
- &thelock->mut, &ts);
+ &thelock->mut, &abs);
+ if (status == 1) {
+ break;
+ }
if (status == ETIMEDOUT)
break;
- CHECK_STATUS_PTHREAD("pthread_cond_timed_wait");
+ CHECK_STATUS_PTHREAD("pthread_cond_timedwait");
}
else {
status = pthread_cond_wait(
diff --git a/configure b/configure
index b78a7b226100..867e2fc28c47 100755
--- a/configure
+++ b/configure
@@ -11448,7 +11448,8 @@ for ac_func in alarm accept4 setitimer getitimer bind_textdomain_codeset chown \
memrchr mbrtowc mkdirat mkfifo \
mkfifoat mknod mknodat mktime mremap nice openat pathconf pause pipe2 plock poll \
posix_fallocate posix_fadvise posix_spawn posix_spawnp pread preadv preadv2 \
- pthread_init pthread_kill putenv pwrite pwritev pwritev2 readlink readlinkat readv realpath renameat \
+ pthread_condattr_setclock pthread_init pthread_kill putenv pwrite pwritev pwritev2 \
+ readlink readlinkat readv realpath renameat \
sem_open sem_timedwait sem_getvalue sem_unlink sendfile setegid seteuid \
setgid sethostname \
setlocale setregid setreuid setresuid setresgid setsid setpgid setpgrp setpriority setuid setvbuf \
diff --git a/configure.ac b/configure.ac
index eeedfedd236f..bb7861bc0daa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3506,7 +3506,8 @@ AC_CHECK_FUNCS(alarm accept4 setitimer getitimer bind_textdomain_codeset chown \
memrchr mbrtowc mkdirat mkfifo \
mkfifoat mknod mknodat mktime mremap nice openat pathconf pause pipe2 plock poll \
posix_fallocate posix_fadvise posix_spawn posix_spawnp pread preadv preadv2 \
- pthread_init pthread_kill putenv pwrite pwritev pwritev2 readlink readlinkat readv realpath renameat \
+ pthread_condattr_setclock pthread_init pthread_kill putenv pwrite pwritev pwritev2 \
+ readlink readlinkat readv realpath renameat \
sem_open sem_timedwait sem_getvalue sem_unlink sendfile setegid seteuid \
setgid sethostname \
setlocale setregid setreuid setresuid setresgid setsid setpgid setpgrp setpriority setuid setvbuf \
diff --git a/pyconfig.h.in b/pyconfig.h.in
index ab9e9e10f7ce..8db06d910068 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -765,6 +765,9 @@
/* Define if your compiler supports function prototype */
#undef HAVE_PROTOTYPES
+/* Define to 1 if you have the `pthread_condattr_setclock' function. */
+#undef HAVE_PTHREAD_CONDATTR_SETCLOCK
+
/* Defined for Solaris 2.6 bug in pthread header. */
#undef HAVE_PTHREAD_DESTRUCTOR
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