SystemExecution in API_Linux.cpp:172: setuid() failed: Resource temporarily unavai...

[harty83]

I have a client who hosts with NetLogistics in Australia. A couple weeks ago, we started to get random 500 internal errors consistently on the site. Consistently being that we are getting the 500 errors but never the same script/url consistently. Its completely random. Everything worked just fine up until a couple weeks ago. Nothing was changed by any of us unless cPanel automatically did something.

I've scoured the logs and the only thing recorded for these errors are similar to:

[Fri Feb 25 15:48:55 2011] [error] [client 58.11.6.200] SystemException in API_Linux.cpp:172: setuid() failed: Resource temporarily unavailable, referer: http://mywebsite.com/myscript.php
[Fri Feb 25 15:48:55 2011] [error] [client 58.11.6.200] Premature end of script headers: myscript.php, referer: http://mywebsite.com/myscript.php

I use suPHP with PHP5 on a CentOS 5.2 server. I have checked, rechecked, and triple checked that ownership and permissions are correct (755 for directories, 644 for files; all owned by user and user's group). I don't think this is a permission issue because of the error's randomness.

I have tried increasing PHP's memory_limit, max_execution_time, etc to no avail. I've tried increasing the number of Apache SpareServers, MaxClients, etc to no avail. I've turned all loglevel's to info but am given nothing.

As far as I know, I have nothing installed that would limit the number of PHP processes unless cPanel has something native. But from what I have read, cPanel does not unless I install a custom suPHP module to limit processes and I have not done so.

Any ideas? I'm pretty much at my wits end ;-)

Thanks,
Alan

[cPanelTristan]

Can you please check if there are actually any RLimit settings in Apache's configuration on the machine?

grep -i rlimit /usr/local/apache/conf/httpd.conf

[harty83]

This is what I'm given:

[15:46:12][root@host:~]# grep -i rlimit /usr/local/apache/conf/httpd.conf
RLimitCPU 240                                                                                                                                                                         
RLimitNPROC 10                                                                                                                                                                        
ServerLimit 250

Thanks,
Alan

[cPanelTristan]

Then you do have limits on your machine. The RLimitNPROC is the one causing the issue. It is limiting each user to 10 processes, which this account is hitting.

You will need to comment out the setting entirely and restart Apache to see if that corrects the issue. If it does, then if this was enabled by using WHM > Memory Usage Restrictions area, then you will need to remove the RLimit entries in /var/cpanel/templates/apache2/main.default by copying that file to /var/cpanel/templates/apache2/main.local and then rebuild Apache:

cp /usr/local/apache/conf/httpd.conf /usr/local/apache/conf/httpd.conf.bak110305
/scripts/rebuildhttpdconf
/etc/init.d/httpd restart