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From Tony Schreiner <>
Subject Re: [users@httpd] Runaway thread, troubleshooting tools needed
Date Wed, 13 Apr 2005 20:04:12 GMT

On Apr 13, 2005, at 3:51 PM, Skylos wrote:

> Greetings,
> I'm pretty new to the concept of threads and debugging them - I
> currently am running...
> Server version: Apache/2.0.53
> Server built:   Mar  6 2005 21:52:49
> I am utilizing the worker mpm to serve a moderate volume website with
> two servers.  I extensively use mod_perl, but I realize this is not a
> mod_perl list.  I purely wish to learn ways of finding out what
> stage/process is going on when this thread/process locks up.  This
> should be general to apache, right?
> My symptoms are that a server will start utilizing 100% of one of the
> 4 cpus.  (this happens on both)  This usually happens within 18 hours
> of a server startup, but seems entirel.y random.  If I do an
> 'apachectl restart', the problem will almost always go away.  However,
> even on shutdown, there will be a several httpd processes left that
> will not die without a kill -9 to them specifically.
> When I display top, it shows the cpu usage, but it doesn't show which
> process is using it - sorting by cpu usage shows no process using more
> than about 0.3% of the cpu.
> I need help.  Can you suggest commands that would allow me to track
> the threads, see what might be happening in the request stream when
> this occurs?
> Hopefully,
> Skylos

I don't have an answer for you, but am experiencing the same problem 
with 2.0.53 compiled and running on OS X server. It was also happening 
with 2.0.52. Mine was also built with MPM=worker

I have attached gdb to the runaway process, and get this backtrace 
(every time the same)

#0  0x9000eac4 in read ()
#1  0x00011030 in ap_mpm_pod_check ()
#2  0x0000ecc8 in child_main ()
#3  0x0000eee8 in make_child ()
#4  0x0000f52c in perform_idle_server_maintenance ()
#5  0x0000f838 in server_main_loop ()
#6  0x0000fc90 in ap_mpm_run ()
#7  0x00012df0 in main ()
#8  0x000029f8 in _start ()
#9  0x0000286c in start ()

but, I'm at a loss of what to investigate next.


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