[mod_python] ValueError: Failed to acquire global mutex lock

Tropezien tropezien at croxx.de
Sun Nov 23 15:16:33 EST 2003

Am Sonntag, 23. November 2003 02:16 schrieb Julian Ciccale:
> Hi,
>    I'm running RH 9 with apache 2.0 (prefork) and modpython 3.1.1b. Sadly
> I'm unable to use the new Session handling classes, I get "Failled to
> acquire global mutex lock" and this on apache's error log "(13)Permission
> denied: Failed to acquire global mutex lock at index 9"
>  Anyone that is getting the same errors?
Yes, I am running Slackware 9.1 with Apache 2.0.47 and mod_python 3.1.2b.
Some further investigations cleared up that mod_python tries to get more than 
400 semaphores during launch of httpd. There is an estimated amount of 16 
threads (AP_MPMQ_MAX_THREADS) for all (25) possible daemon-process 
My quick and dirty solution was to increase the amount of system semaphores 
supported by the Linux-kernel with

    >georg at jeordi:/etc/rc.d$ /sbin/sysctl kernel.sem
    kernel.sem = 256        32000   32      512

I changed my /etc/sysctl.conf to:

    kernel.sem = 500 32000 32 512

and added the line:

    sysctl -p

into the Init-Skript of the Apache (rc.httpd) before the httpd-daemon is 

Ciao, Georg

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