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From: Kaz Kylheku <643-408-1753@kylheku.com>
Newsgroups: comp.lang.c
Subject: Re: best approach for multithreading (?)
Date: Sun, 8 Dec 2024 09:31:45 -0000 (UTC)
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On 2024-12-08, Chris M. Thomasson <chris.m.thomasson.1@gmail.com> wrote:
> On 12/7/2024 7:49 PM, Kaz Kylheku wrote:
>> On 2024-12-07, James Kuyper <jameskuyper@alumni.caltech.edu> wrote:
>>> My words above not-withstanding, I am not in any sense an expert on any
>>> kind of threading, nor of Windows. What does POSIX require of threads
>>> with regards to signals?
>> 
>> Off the top of my head, the highlights:
>> 
>> - threads have their own signal masks, inherited from the creator which
>>    calls pthtead_create.
>> - signal masks can be manipulated so that a given signal will be
>>    handled in the context of a desired thread.
>> - sigwait (and several other functions) can be used by a thread to
>>    wait for one or more signals, allowing signals to be process
>>    synchronously, somewhat like message passing.
>> 
>
> Semaphores are sig safe, so to speak. It's been a while:
>
> https://www.man7.org/linux/man-pages/man3/sem_post.3.html
>
> should be sig safe? Or, am I wrong here Kaz?

Yes; just not sem_wait. The obvious idea there is that a signal handler
is like an interrupt service top half, and those must be able to bang
semaphores, to wake up something waiting in the bottom half code.

-- 
TXR Programming Language: http://nongnu.org/txr
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