Author: Matti Picus <[email protected]>
Branch: semlock-deadlock
Changeset: r96545:f3621100820d
Date: 2019-04-27 09:18 -0700
http://bitbucket.org/pypy/pypy/changeset/f3621100820d/
Log: fix RECURSIVE semaphore by setting state before, not after, glibc
call
diff --git a/pypy/module/_multiprocessing/interp_semaphore.py
b/pypy/module/_multiprocessing/interp_semaphore.py
--- a/pypy/module/_multiprocessing/interp_semaphore.py
+++ b/pypy/module/_multiprocessing/interp_semaphore.py
@@ -46,7 +46,8 @@
eci = ExternalCompilationInfo(
includes = ['sys/time.h',
'limits.h',
- 'semaphore.h'],
+ 'semaphore.h',
+ ],
libraries = libraries,
)
@@ -333,15 +334,11 @@
_sem_close_no_errno(handle)
def semlock_acquire(self, space, block, w_timeout):
- import threading
- myid = threading.current_thread().ident
if not block:
- print 'not expected'
deadline = lltype.nullptr(TIMESPECP.TO)
elif space.is_none(w_timeout):
deadline = lltype.nullptr(TIMESPECP.TO)
else:
- print 'not expected'
timeout = space.float_w(w_timeout)
sec = int(timeout)
nsec = int(1e9 * (timeout - sec) + 0.5)
@@ -360,16 +357,12 @@
while True:
try:
if not block:
- print 'not expected'
sem_trywait(self.handle)
elif not deadline:
- print 'sem_wait', myid
sem_wait(self.handle)
else:
- print 'not expected'
sem_timedwait(self.handle, deadline)
except OSError as e:
- print str(e)
if e.errno == errno.EINTR:
# again
_check_signals(space)
@@ -377,9 +370,7 @@
elif e.errno in (errno.EAGAIN, errno.ETIMEDOUT):
return False
raise
- print 4, myid
- _check_signals(space)
- print 5, myid
+ _check_signals(space)
return True
finally:
if deadline:
@@ -387,9 +378,6 @@
def semlock_release(self, space):
- import threading
- myid = threading.current_thread().ident
- print 'semlock_release', myid
if self.kind == RECURSIVE_MUTEX:
sem_post(self.handle)
return
@@ -451,6 +439,7 @@
self.count = 0
self.maxvalue = maxvalue
self.register_finalizer(space)
+ self.last_tid = -1
def kind_get(self, space):
return space.newint(self.kind)
@@ -488,35 +477,42 @@
if self.kind == RECURSIVE_MUTEX and self._ismine():
self.count += 1
return space.w_True
-
+ owner_id = self.last_tid
try:
+ # Ideally these calls would be atomic. Since we cannot
+ # promise that, make sure we do not enable the fast-path
+ # through release anymore
+ self.last_tid = rthread.get_ident()
got = semlock_acquire(self, space, block, w_timeout)
except OSError as e:
+ self.last_tid = owner_id
raise wrap_oserror(space, e)
if got:
- self.last_tid = rthread.get_ident()
self.count += 1
return space.w_True
else:
+ self.last_tid = owner_id
return space.w_False
def release(self, space):
if self.kind == RECURSIVE_MUTEX:
- if not self._ismine():
- raise oefmt(space.w_AssertionError,
- "attempt to release recursive lock not owned by "
- "thread")
- if self.count > 1:
+ # another thread may be in the middle of an acquire and
+ # have set the last_tid already
+ if self._ismine() and self.count > 1:
self.count -= 1
return
try:
+ # Ideally these two calls would be atomic. Since we cannot
+ # promise that, make sure once we release the lock the count
+ # will be correct
+ self.count -= 1
semlock_release(self, space)
except OSError as e:
+ self.count += 1
raise wrap_oserror(space, e)
- self.count -= 1
def after_fork(self):
self.count = 0
diff --git a/pypy/module/_multiprocessing/test/test_semaphore.py
b/pypy/module/_multiprocessing/test/test_semaphore.py
--- a/pypy/module/_multiprocessing/test/test_semaphore.py
+++ b/pypy/module/_multiprocessing/test/test_semaphore.py
@@ -112,11 +112,14 @@
def test_in_threads(self):
from _multiprocessing import SemLock
from threading import Thread
+ from time import sleep
l = SemLock(0, 1, 1)
- def f():
- for i in range(10000):
+ def f(id):
+ for i in range(1000):
with l:
pass
- threads = [Thread(None, f) for i in range(2)]
+ threads = [Thread(None, f, args=(i,)) for i in range(2)]
[t.start() for t in threads]
+ # if the RLock calls to sem_wait and sem_post do not match,
+ # one of the threads will block and the call to join will fail
[t.join() for t in threads]
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