Hi Greg: Although the patch you sent fixes the problem of multiple pods,
there are still some problems. With the following configuration:
StartServers 6
MinSpareThreads 5
MaxSpareThreads 50
one would expect that when I start the web-server, since I have 6 processes,
hence 150 threads (all of them idle), the MaxSpareThreads is exceeded. This
should result in the killing of 4 spare processes. This does not happen. A
"ps" will show that all the 6 processes are still around.
The explanation is as follows, the p_i_s_m() would send 4 pods to kill the 4
spare processes, so that there are only 2 processes running. While this is
the correct behaviour, the processes which have recd the pod do not die
immediately.
This happens due to multiple threads (from all the 6 different processes)
blocked at apr_lock_acquire(accept_mutex) statement in worker_thread()
routine, as the accept_mutex is a server-wide mutex. Since only one thread
makes into the critical section, if the thread that enters the cs is from a
process which hasn't recd a pod, then it would block at the apr_poll()
routine. Now the other threads from the processes that have recd the pod,
are still blocked at apr_lock_acquire(), and hence cannot exit - causing the
processes to be alive.
Again, the patch that Justin re-posted, with two mutexes - per-process and
server-wide - resolves the problem completely. (I say almost, as there is
still a small timing window between two consecutive runs of p_i_s_m() and
updating the quiescing flag within the worker_thread() routine). Both the
fixes together - yours and Justin's - will fix the problem.
The patch Justin posted is with the new functions ap_mpm_pod_check() etc. A
similar patch with check_pipe_of_death() routines themselves could be used
too - if you need, I could post that.
Thoughts/comments?
Thanks,
M
> -----Original Message-----
> From: Greg Ames [mailto:[EMAIL PROTECTED]]
> Sent: Monday, July 30, 2001 8:56 PM
> To: [EMAIL PROTECTED]
> Subject: Re: tarballs are up
>
>
> "GUMMALAM,MOHAN (HP-Cupertino,ex2)" wrote:
> >
> > Greg: Though I haven't completed testing the fix you
> suggested, I am
> > certain it would resolve the situation of multiple pods
> being sent. I had a
> > pretty similar suggestion, which I had sent to the list a
> while back, and
> > hence my conviction that this will work. I'll let you know
> what comes
> > through!
> > Thanks,
> > M
>
> you're welcome - it's commited.
>
> I went back and saw the patch you posted earlier this month.
> That would
> have done the job, too. My apologies for not paying enough
> attention to
> it at first - e-mail overload after being at sea for 2 1/2 weeks.
>
> You also mentioned a patch Justin posted with two mutexes:
>
> > Justin's patch of two mutexes did fix the problem, but I
> do not see it being included
> > even now.
>
> Either I deleted that one, or I can't figure out which one it
> is amongst
> the others. Justin, could you please re-post this one?
>
> and does anyone know where the new-httpd mail archive lives any more?
>
> Greg
>
