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[Python-Dev] Issue with _thread.interrupt_main (29926)

Martin Panter vadmium+py at gmail.com
Tue Mar 28 02:00:11 EDT 2017 
On 28 March 2017 at 03:11, Steven D'Aprano <steve at pearwood.info> wrote:
> On Mon, Mar 27, 2017 at 10:33:44PM -0400, Terry Reedy wrote:
>> https://bugs.python.org/issue29926 was opened as an IDLE issue, which
>> means that most watching the new issues list would ignore it.  But I
>> think it is an issue with _thread.interrupt_main (which IDLE calls in
>> respond to ^C) not interrupting time.sleep(n) in main thread*.  I tested
>> on Windows, don't know yet about OP.  Since there is no Expert's Index
>> listing for _thread (or threading), I am asking here for someone who
>> knows anything to take a look.
>>
>> *
>> >>> time.sleep(10)
>> <hit ^C immediately>
>> <debug print after interrupt_main() shows immediately>
>> <... remainder of 10 seconds pass>
>> KeyboardInterrupt
>
>
> I get similar behaviour under Linux. I don't have the debug print, but
> the KeyboardInterrupt doesn't interrupt the sleep until the 10 seconds
> are up.

Looking at the implementation, _thread.interrupt_main just calls
PyErr_SetInterrupt. It doesn’t appear to send a signal. I played with
“strace” and couldn’t see any evidence of a signal. I guess it just
sets a flag that will be polled. To actually interrupt the “sleep”
call, you might need to use “pthread_kill” or similar (at least on
Unix).
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