Re: [linux-audio-dev] shared memory problems

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Subject: Re: [linux-audio-dev] shared memory problems
From: Richard Guenther (rguenth_AT_tat.physik.uni-tuebingen.de)
Date: Wed Nov 14 2001 - 11:08:15 EET

On Tue, 13 Nov 2001, Paul Davis wrote:

> >> i wish there was a way force certain things to happen when a process
> >> dies on SIGKILL, though. we can't call shmctl(id,IPC_RMID) on shm
> >> segments until we know that no more clients will attempt to connect -
> >> i.e. the server is exiting (because a "marked-destroyed" segment
> >> cannot be accessed by a new task). thus, i defer this via
> >> on_exit(). alas, these are not called if it dies with SIGKILL, and we
> >> end up with "persistent" shm segments. sigh. at least i can handle all
> >> other signals properly.
> >
> >Well, its easy to do this. Just have the server do a fork() early at
> >startup time, have the new process be the server and the parent just
> >waiting on the server and doing necessary cleanup. Just like X does
> >with Xwrapper.
>
> sounds great. except that also means defining some IPC protocol so
> that the server can tell the wrapper about shm resources and files
> that need to be released, right? they're not in the same address
> space.

Well, either allocate all resources before fork() (if possible), or
have a resource list in a shm region allocated before fork(). Something
along this should be the simplest (rather than setting up another
comm via sockets or the like).

Richard. 

--
Richard Guenther <richard.guenther_AT_uni-tuebingen.de>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/
The GLAME Project: http://www.glame.de/

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