URGENT Apache has suddenly started crashing

[elemental.tm]

Urgent assistance required, Apache has suddenly started crashing and I am unsure why. Any assistance would be most welcome.

Error log:

[Tue May 10 18:46:07 2011] [notice] mod_ruid2/0.9.4 enabled
[Tue May 10 18:46:07 2011] [notice] Apache/2.2.9 (Debian) mod_fcgid/2.3.5 mod_python/3.3.1 Python/2.5.2 mod_ssl/2.2.9 OpenSSL/0.9.8g mod_perl/2.0.4 Perl/v5.10.0 configured -- resuming normal operations
[Tue May 10 20:10:37 2011] [error] [client 174.129.199.110] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind
[Tue May 10 20:10:38 2011] [error] [client 174.129.199.110] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind
[Tue May 10 20:10:38 2011] [error] [client 174.129.199.110] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /w00tw00t.at.ISC.SANS.DFind
[Tue May 10 20:10:38 2011] [emerg] (13)Permission denied: couldn't grab the accept mutex
[Tue May 10 20:10:38 2011] [alert] Child 32333 returned a Fatal error... Apache is exiting!
[Tue May 10 20:10:38 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue May 10 20:10:38 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue May 10 20:10:38 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue May 10 20:10:38 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue May 10 20:10:38 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue May 10 20:10:38 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue May 10 20:10:38 2011] [emerg] (43)Identifier removed: couldn't grab the accept mutex
[Tue May 10 20:10:41 2011] [emerg] (22)Invalid argument: couldn't grab the accept mutex
[Tue May 10 20:10:47 2011] [emerg] (22)Invalid argument: couldn't release the accept mutex

Plesk 10.2
Debian 5 64-bit

Thanks in advance.

 

[IgorG]

Unfortunately, such problems with Apache crashing are type of problems that can't be effectively resolved by forum discussions. It is require detailed investigation directly on server, tuning of Apache config, investigation of environment, configs, resources allocation, etc... Apache crashing is complex problem.
If you try to google "Permission denied: couldn't grab the accept mutex" you can see recommendations like

http://www.issociate.de/board/index.php?t=msg&th=51105&rid=0
http://bugs.xampp.org/view.php?id=110

But generally such problems should be deeply investigated by Parallels Support Team. I recommend you contact Support in these cases.

 

[elemental.tm]

Thanks for the update IgorG.

 

[elemental.tm]

Sam that Dog!

It seems the problem was caused by Watchdog! Which seems to be broken in Plesk 10.2. I uninstalled it and the errors went away. I request Parallels review Watchdog and resolve and patch any issues found.