Proccess stucked with the status W ("Sending Reply")

[edgardnog]

Hi,

We are having a strange problem. We don´t know why, but the Apache proccess get stucked with the status W ("Sending Reply), so the process don´t die and apache "crash" because a lot of process. When this happens i just restart the Apache and the proccess stop to get the W status, and everything starts to work fine again.

This problems happens a lot of times during the day, so it happen when we are geting a lot of traffic and when we are getting low traffic.

I had try very hard to find out what is the problem, but the only thing that i found is that the problem isn´t the bandwith or database problems.

We run our site with
linux: Gentoo
Apache
php + Mysql.

Can anyone help me with this?

sory for my bad english

 

[elgrandeperro]

Same URL?
Is the client IP the same?
Perhaps DOS attack, probably unlikely.

strace the process, see if it is polling, perhaps a thread lock in PHP.

Take a snapshot of the status and compare a few minutes later. Are any of the waiting processes ever completed?

scroll down the Apache timeout from the default 300 might give you relief but not fix the problem.

Is the webserver behind a firewall?
eugene

 

[edgardnog]

Hi eugene, thanks for you reply

Our site is behind a firewall. I don´t think it is a DOS attack. They are different IP, and also different urls.

Does anyone know anything that can help me to solve this problem?

Thanks, edgard

 

[elgrandeperro]

Enable customlogs to see if it might be a proxy problem.
eugene

 

[RhythmAce]

Check php and mysql. A lot of times something like this can be traced back to mysql going a little nuts. If all looks well, check your memory and cpu usage. A pooly written script can cause memory leaks if not mojor hemorrhaging. Don't put too much faith in your firewall. It's not the people it keeps out that will cause problems. It's those it lets in. If there is a way into your system such as any server open to the public, they are already past your firewall. Now they will use any port to find a way to exploit it. You need to keep up with the latest info and keep your system up to date on all security updates. Check the software developers websites to see if any vulnerabilities have been found and how to fix them.