Re: best approach for multithreading (?)

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.

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