Issue #14753: Make multiprocessing treat negative timeouts as it did in 3.2
In Python 3.2 and earlier, Process.join() and Connection.poll()
treated negative timeouts as zero timeouts. Earlier versions from
the 3.3 line of development treat them as infinite timeouts.
The patch reverts to the old behaviour.
diff --git a/Doc/library/multiprocessing.rst b/Doc/library/multiprocessing.rst
index bdc07f1..320e492 100644
--- a/Doc/library/multiprocessing.rst
+++ b/Doc/library/multiprocessing.rst
@@ -928,6 +928,12 @@
.. note::
+ The :meth:`acquire` and :meth:`wait` methods of each of these types
+ treat negative timeouts as zero timeouts. This differs from
+ :mod:`threading` where, since version 3.2, the equivalent
+ :meth:`acquire` methods treat negative timeouts as infinite
+ timeouts.
+
On Mac OS X, ``sem_timedwait`` is unsupported, so calling ``acquire()`` with
a timeout will emulate that function's behavior using a sleeping loop.
@@ -1899,6 +1905,7 @@
those objects in *object_list* which are ready. If *timeout* is a
float then the call blocks for at most that many seconds. If
*timeout* is ``None`` then it will block for an unlimited period.
+ A negative timeout is equivalent to a zero timeout.
For both Unix and Windows, an object can appear in *object_list* if
it is
diff --git a/Lib/multiprocessing/connection.py b/Lib/multiprocessing/connection.py
index acf43b1..56f375d 100644
--- a/Lib/multiprocessing/connection.py
+++ b/Lib/multiprocessing/connection.py
@@ -23,8 +23,7 @@
import _multiprocessing
from multiprocessing import current_process, AuthenticationError, BufferTooShort
-from multiprocessing.util import (
- get_temp_dir, Finalize, sub_debug, debug, _eintr_retry)
+from multiprocessing.util import get_temp_dir, Finalize, sub_debug, debug
from multiprocessing.forking import ForkingPickler
try:
import _winapi
@@ -323,8 +322,6 @@
if (self._got_empty_message or
_winapi.PeekNamedPipe(self._handle)[0] != 0):
return True
- if timeout < 0:
- timeout = None
return bool(wait([self], timeout))
def _get_more_data(self, ov, maxsize):
@@ -402,8 +399,6 @@
return self._recv(size)
def _poll(self, timeout):
- if timeout < 0.0:
- timeout = None
r = wait([self._handle], timeout)
return bool(r)
diff --git a/Lib/multiprocessing/forking.py b/Lib/multiprocessing/forking.py
index ca03e95..2729afe 100644
--- a/Lib/multiprocessing/forking.py
+++ b/Lib/multiprocessing/forking.py
@@ -75,12 +75,9 @@
#
if sys.platform != 'win32':
- import select
-
exit = os._exit
duplicate = os.dup
close = os.close
- _select = util._eintr_retry(select.select)
#
# We define a Popen class similar to the one from subprocess, but
@@ -130,10 +127,10 @@
def wait(self, timeout=None):
if self.returncode is None:
if timeout is not None:
- r = _select([self.sentinel], [], [], timeout)[0]
- if not r:
+ from .connection import wait
+ if not wait([self.sentinel], timeout):
return None
- # This shouldn't block if select() returned successfully.
+ # This shouldn't block if wait() returned successfully.
return self.poll(os.WNOHANG if timeout == 0.0 else 0)
return self.returncode
diff --git a/Lib/multiprocessing/util.py b/Lib/multiprocessing/util.py
index da99063..9b6dac2 100644
--- a/Lib/multiprocessing/util.py
+++ b/Lib/multiprocessing/util.py
@@ -295,18 +295,3 @@
register_after_fork(self, lambda obj : obj.__dict__.clear())
def __reduce__(self):
return type(self), ()
-
-
-#
-# Automatic retry after EINTR
-#
-
-def _eintr_retry(func):
- @functools.wraps(func)
- def wrapped(*args, **kwargs):
- while True:
- try:
- return func(*args, **kwargs)
- except InterruptedError:
- continue
- return wrapped
diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index a839917..d10d51b 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -83,23 +83,13 @@
'HAVE_BROKEN_SEM_GETVALUE', False)
WIN32 = (sys.platform == "win32")
-if WIN32:
- from _winapi import WaitForSingleObject, INFINITE, WAIT_OBJECT_0
- def wait_for_handle(handle, timeout):
- if timeout is None or timeout < 0.0:
- timeout = INFINITE
- else:
- timeout = int(1000 * timeout)
- return WaitForSingleObject(handle, timeout) == WAIT_OBJECT_0
-else:
- from select import select
- _select = util._eintr_retry(select)
+from multiprocessing.connection import wait
- def wait_for_handle(handle, timeout):
- if timeout is not None and timeout < 0.0:
- timeout = None
- return handle in _select([handle], [], [], timeout)[0]
+def wait_for_handle(handle, timeout):
+ if timeout is not None and timeout < 0.0:
+ timeout = None
+ return wait([handle], timeout)
try:
MAXFD = os.sysconf("SC_OPEN_MAX")
@@ -291,9 +281,18 @@
self.assertIn(p, self.active_children())
self.assertEqual(p.exitcode, None)
+ join = TimingWrapper(p.join)
+
+ self.assertEqual(join(0), None)
+ self.assertTimingAlmostEqual(join.elapsed, 0.0)
+ self.assertEqual(p.is_alive(), True)
+
+ self.assertEqual(join(-1), None)
+ self.assertTimingAlmostEqual(join.elapsed, 0.0)
+ self.assertEqual(p.is_alive(), True)
+
p.terminate()
- join = TimingWrapper(p.join)
self.assertEqual(join(), None)
self.assertTimingAlmostEqual(join.elapsed, 0.0)
@@ -1664,6 +1663,9 @@
self.assertEqual(poll(), False)
self.assertTimingAlmostEqual(poll.elapsed, 0)
+ self.assertEqual(poll(-1), False)
+ self.assertTimingAlmostEqual(poll.elapsed, 0)
+
self.assertEqual(poll(TIMEOUT1), False)
self.assertTimingAlmostEqual(poll.elapsed, TIMEOUT1)
@@ -2785,6 +2787,16 @@
p.terminate()
p.join()
+ def test_neg_timeout(self):
+ from multiprocessing.connection import wait
+ a, b = multiprocessing.Pipe()
+ t = time.time()
+ res = wait([a], timeout=-1)
+ t = time.time() - t
+ self.assertEqual(res, [])
+ self.assertLess(t, 1)
+ a.close()
+ b.close()
#
# Issue 14151: Test invalid family on invalid environment
diff --git a/Misc/NEWS b/Misc/NEWS
index f383e91..d123c01 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -23,6 +23,9 @@
Library
-------
+- Issue #14753: Make multiprocessing's handling of negative timeouts
+ the same as it was in Python 3.2.
+
- Issue #14583: Fix importlib bug when a package's __init__.py would first
import one of its modules then raise an error.