Re: Terminating threads in a process,WAS: RE: [PATCH] Problems with MPM threaded

[Brian Pane]

Aaron Bannert wrote:

>>I'm not sure that the alternative is workable, either.
>>
>>At the time of the fork, when the child process gets a snapshot of
>>the parent's memory, it's possible that some thread other than the one
>>invoking fork could be halfway through registering a new resource (e.g.,
>>file descriptor) in its pool.  There's no guarantee that it's safe to
>>attempt a cleanup of that other thread's pool in the child process;
>>if the fork has caught the data structures in an intermediate state,
>>attempting to destroy that pool might yield a segv.
>>
>
>Correct me if I'm wrong, but that would be a property of a buggy MPM.
>If the MPM chooses to mix non-synchronized fork()s and thread invocation,
>than that's what it gets.
>
Synchronizing the forks with pool resource registration isn't a scalable
design; it requires locking a process-wide lock every time you want to
register a resource in a per-thread pool.  It would be a huge mistake
to slow down the routine operation of the httpd in order to optimize for
fork.

--Brian