Linux – why apache2 process is eating so much CPU

apache-2.2linux

This is my top output print.
enter image description here

Basically my site hangs on and the server needs to be restarted once at 4-5 hours…I supposed that mysql is the issue so I disabled some hard queries but I still see problems on apache…

Is there a way to find out why my apache process is eating so much cpu?

Best Answer

Try using http://httpd.apache.org/docs/2.0/mod/mod_status.html and/or looking into the server logs and see what script is executing. I'm assuming its a script that entered an infine loop somehow

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Linux – Java process eating CPU; Why

If you stop the solr process and a java process is still running, then there's another java process on your server. The first step is to document all of the Java processes that are running. A good tool for this on Unix is the ps tool. Try this:

$ ps auxwww | grep java

That output should show you all of the java processes running, and the commands that are being executed. Try this before and after you stop solr.

The second question is "which of these java processes is eating up so much CPU"? You may need to stop the jetty process in addition to the solr process. Also, you should never really need to restart a Linux server just because a single process is misbehaving. You can also use the kill command to stop a process if you now it's process id, which you can get from either top or ps.

In the short term it may be a good idea to install some sort of "watchdog" script on your machine to help with these situations. For example, monit can be used to automatically restart a service or process when it consumes a certain amount of CPU resources.

In the long term, I'm sorry to say that you have a performance issue. You need to look at reconfiguring solr and jetty at the very least. You may also need to look into garbage collection tuning and possibly adding more hardware. There's lots of information on these topics online, and I'm sorry to say that this process can be somewhat difficult.

Good luck!

Tom Purl

Httpd – Apache taking up too much CPU

Looks to me like you're using the prefork mpm. Most of this answer assumes as much.

It appears Apache is creating a new process for every single connection. Is this normal?

For prefork? Yes.

Is there a way to more quickly kill the sleeping processes?

Are you sure these processes are not doing anything? With your MaxSpareSevers setting you should only have up to 50 idle processes. Enable mod_status and set ExtendedStatus on should allow you to view the Apache scoreboard and allow you to see what is going on.

Should we turn KeepAlive on? Each page loads about 15-20 medium-sized graphics and a lot of javascript/css.

Turning on KeepAlive is a good idea. It will allow clients to pipeline requests and allow you to reuse Apache processes more efficiently.

As with most tuning. Measure first to create you baseline, then change one thing and then re-measure to try determine what effect you change may have had. Using (and graphing) mod_status is handy for this.

You may be able to use the worker mpm, which tends to help with performance. However, some libraries (notably some PHP libraries) do not operate well with the worker mpm. YMMV

To determine which mpm you're using run: apache2 -V (or httpd -V depending on the distro)

Best Answer

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Linux – Java process eating CPU; Why

Httpd – Apache taking up too much CPU

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