Re: call-process blocks the active thread

[Philipp Stephani <p.stephani2@gmail.com>]

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Elias Mårtenson <lokedhs@gmail.com> schrieb am Fr., 8. Sep. 2017 um
13:00 Uhr:

> On 8 September 2017 at 15:01, Eli Zaretskii <eliz@gnu.org> wrote:
>
>> > From: Elias Mårtenson <lokedhs@gmail.com>
>> > Date: Fri, 8 Sep 2017 11:00:42 +0800
>> >
>> > As it turns out, ‘call-process’ hangs all of Emacs while the external
>> program is run.
>>
>> No, it hangs the calling thread, and the other threads wait for the
>> calling thread to yield.  To avoid that, use start-process instead.
>>
>> This is not a bug.
>>
>
> I'm not entirely sure why you feel that distinction is important. At the
> end of the day, it's ‘start-process’ that doesn't yield while the external
> process runs. Is there a reason why it can't be changed so that it does?
>

Emacs threads can't run in parallel because they share global mutable state
(buffers etc.) without synchronization. `call-process' is guaranteed to not
affect the global state in "significant" ways, therefore it can't yield to
threads that could change the global state.
It's not possible to fix this.

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