C++ Embedded 'time.sleep()' is not working on Windows host due to 'Py_InitializeEx(0)'

[hafizbilal100]

BPO	41686
Nosy	@pfmoore, @vstinner, @tjguk, @zware, @eryksun, @zooba
PRs	bpo-41686: Always create the SIGINT event on Windows #23344 bpo-41686: Refactor signal_exec() #23346 [3.9] bpo-41686: Always create the SIGINT event on Windows (GH-23344) #23347 [3.8] bpo-41686: Always create the SIGINT event on Windows (GH-23344) (GH-23347) #23349 bpo-41686: Move _Py_RestoreSignals() to signalmodule.c #23353

^{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 2020-11-17.21:26:11.457>
created_at = <Date 2020-09-01.12:32:23.361>
labels = ['type-bug', '3.8', '3.9', '3.10', 'expert-C-API', 'OS-windows']
title = "C++ Embedded 'time.sleep()' is not working on Windows host due to 'Py_InitializeEx(0)'"
updated_at = <Date 2020-11-17.21:56:51.779>
user = 'https://bugs.python.org/hafizbilal100'

bugs.python.org fields:

activity = <Date 2020-11-17.21:56:51.779>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-11-17.21:26:11.457>
closer = 'vstinner'
components = ['Windows', 'C API']
creation = <Date 2020-09-01.12:32:23.361>
creator = 'hafizbilal100'
dependencies = []
files = []
hgrepos = []
issue_num = 41686
keywords = ['patch']
message_count = 13.0
messages = ['376189', '376196', '376219', '376220', '376232', '376265', '381257', '381265', '381266', '381286', '381288', '381292', '381294']
nosy_count = 7.0
nosy_names = ['paul.moore', 'vstinner', 'tim.golden', 'zach.ware', 'eryksun', 'steve.dower', 'hafizbilal100']
pr_nums = ['23344', '23346', '23347', '23349', '23353']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue41686'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

[hafizbilal100]

Hi,

time.sleep() function is not working on Windows host if I use C API Py_InitializeEx(0) function.

Issue could be reproduce with following simple example.

int main()
{
   Py_InitializeEx(0);
   PyRun_SimpleString("import time \n"
		      "start = time.time() \n"
		      "time.sleep(4) \n"
		      "print('elapsed: %d' % (time.time() - start))");
}

output:

elapsed: 0

Note, issue is not reproduce on Linux host.

[eryksun]

The SIGINT event gets created when the _signal extension module is imported. Until then, _PyOS_SigintEvent() returns NULL. But currently all code that calls _PyOS_SigintEvent() assumes it returns a valid handle. This has to be fixed to support Py_InitializeEx(0).

For example, pysleep could call WinAPI Sleep on the main thread if the interrupt event isn't configured:

        ul_millis = (unsigned long)millisecs;
        hInterruptEvent = _PyOS_SigintEvent();

        if (ul_millis == 0 || !hInterruptEvent || !_PyOS_IsMainThread()) {
            Py_BEGIN_ALLOW_THREADS
            Sleep(ul_millis);
            Py_END_ALLOW_THREADS
            break;
        }

[vstinner]

Py_InitializeEx() should be modified to always initialize sigint_event, even if install_sigs is equal to zero.

Maybe the variable should be moved somewhere else. Maybe in the time module?