PEP 475: handle EINTR in the time module, retry sleep()

[vstinner]

BPO	23646
Nosy	@pitrou, @vstinner
Files	sleep_eintr.patch sleep.py sleep_eintr-2.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2015-03-19.23:00:18.411>
created_at = <Date 2015-03-12.15:37:42.547>
labels = []
title = 'PEP 475: handle EINTR in the time module, retry sleep()'
updated_at = <Date 2015-03-20.02:06:25.652>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2015-03-20.02:06:25.652>
actor = 'python-dev'
assignee = 'none'
closed = True
closed_date = <Date 2015-03-19.23:00:18.411>
closer = 'vstinner'
components = []
creation = <Date 2015-03-12.15:37:42.547>
creator = 'vstinner'
dependencies = []
files = ['38454', '38455', '38457']
hgrepos = []
issue_num = 23646
keywords = ['patch']
message_count = 11.0
messages = ['237948', '237949', '237952', '237953', '237959', '237983', '238269', '238270', '238557', '238594', '238599']
nosy_count = 4.0
nosy_names = ['pitrou', 'vstinner', 'neologix', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue23646'
versions = ['Python 3.5']

[vstinner]

Attached patch changes time.sleep() to retry select() when select() is interrupted by a signal or retry WaitForSingleObjectEx() when the signal SIGINT is received on Windows.

The patch drops support for EMX, sorry! I didn't know EMX, I had to Google it: "EMX is a free 32-bit DOS extender which adds some properties of Unix to MS-compatible DOS and IBM's OS/2 operating systems." (OS/2 support was dropped in Python 3.4 by the PEP-11.)

The patch also drops support for Watcom C compiler. I guess that it's also something specific to MS-DOS or very old (and unsupported) Windows versions.

select.select() is available on all platforms according to the doc, so I don't understand why we would not use it on all platforms for time.sleep() in 2015!
https://docs.python.org/dev/library/select.html#select.select

[vstinner]

The patch includes a unit test for POSIX.

For Windows, you can test manually using the attached sleep.py program: press CTRL+c to send SIGINT signals.

[vstinner]

Oh, test_signal fails with the patch because time.sleep() is not interrupted by a signal. New patch.

I also reverted #ifdef order in floatsleep() to have a patch easier to review.

[vstinner]

Note: test_signal will have to be modified again when select will also retry on EINTR :-) See issue bpo-23485. For example, test_signal.test_wakeup_fd_early() can register a signal handler which raises an exception and catch InterruptedError.

[neologix]

As for the change to select/poll/etc, IIRC Guido was opposed to it,
that's why I didn't update them.

[vstinner]

Le jeudi 12 mars 2015, Charles-François Natali <report@bugs.python.org> a
écrit :

As for the change to select/poll/etc, IIRC Guido was opposed to it,
that's why I didn't update them.

Wait what? can you elaborate? I'm not aware of that.

[python-dev]

New changeset 4accc35cbfcf by Victor Stinner in branch 'default':
Revert changeset d927047b1d8eb87738676980a24930d053ba2150
https://hg.python.org/cpython/rev/4accc35cbfcf

[vstinner]

I commited sleep_eintr.patch by mistake. After this change, test_socket started to fail on Windows. I don't understand why.

http://buildbot.python.org/all/builders/AMD64%20Windows7%20SP1%203.x/builds/5836/steps/test/logs/stdio

======================================================================
ERROR: testClose (test.test_socket.TCPCloserTest)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_socket.py", line 3723, in testClose
    read, write, err = select.select([sd], [], [], 1.0)
TypeError: argument must be an int, or have a fileno() method.

======================================================================
FAIL: testRecv (test.test_socket.NonBlockingTCPTests)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_socket.py", line 3883, in testRecv
    self.fail("Error trying to do non-blocking recv.")
AssertionError: Error trying to do non-blocking recv.

[python-dev]

New changeset b1abd06465fc by Victor Stinner in branch 'default':
Issue bpo-23646: If time.sleep() is interrupted by a signal, the sleep is now
https://hg.python.org/cpython/rev/b1abd06465fc

[python-dev]

New changeset 9882cc2efd36 by Victor Stinner in branch 'default':
Issue bpo-23646: Enhance precision of time.sleep() and socket timeout when
https://hg.python.org/cpython/rev/9882cc2efd36

[python-dev]

New changeset 1291649f38df by Victor Stinner in branch 'default':
Issue bpo-23646: Fix test_threading on Windows
https://hg.python.org/cpython/rev/1291649f38df