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czamora 12-19-2006 08:18 AM

Centos 4 runs out of memory where Centos 3 didn't!
 
Hi,

I have been running a web server on the typical LAMP configuration for a long time. For the last months it was on Centos 3 and everything went ok. Then I upgraded to Centos 4, and suddenly the server runs out of memory every so often (alsmost once a day) and needs to be rebooted. The only thing I did was to upgrade to a "supposedly" improved distro version!

When the memory is low, and if it lets me run "ps -ef" what I see is dozens of httpd and sendmail processes (my web site does allow for users to send email messages among themselves).

Any hints on what may be causing this?

Thanks a lot.

Brian1 12-20-2006 05:26 PM

Have those two programs been updated during the centos upgrade. If so maybe check to see if there are updates for them. There could be a bug in your current versions. If those were upgraded and no newer updates then downgrade to know working versions unless there were security issues when them.

Brian

NSWKim 12-20-2006 05:36 PM

Hi,

You might try running a "pstree" or "ps faux" to get an idea of all the threads and what sort of memory they are using. Chances are there's a memory leak in one of the applications. I've also seen problems with bad RAM which make swap fill up to 100% then the machine crashes. You can check you free memory and swap with a "free -m".

czamora 12-21-2006 09:20 AM

Quote:

Originally Posted by Brian1
Have those two programs been updated during the centos upgrade. If so maybe check to see if there are updates for them. There could be a bug in your current versions. If those were upgraded and no newer updates then downgrade to know working versions unless there were security issues when them.

Brian

I have done a complete upgrade of the system, to see if that solved the problem, but did not change anything.
I'm not sure if the httpd version was upgraded during the OS change, but it could be. But I'm not sure how I can downgrade that (I know how to update with "yum upgrade", but always to the last version). Do you know how to downgrade to a specific version?

Thanks.

czamora 12-21-2006 09:25 AM

Quote:

Originally Posted by NSWKim
Hi,

You might try running a "pstree" or "ps faux" to get an idea of all the threads and what sort of memory they are using. Chances are there's a memory leak in one of the applications. I've also seen problems with bad RAM which make swap fill up to 100% then the machine crashes. You can check you free memory and swap with a "free -m".

Mmmm, it seems that during normal operation there are 20 instances of httpd, each consuming 2% of memory (that adds up to 40%). But apart from that, and 3% for mysqld, there are no other processes consuming memory.

The thing is also, if there is a memory leak, it is not continuous, and only shows from time to time (once every other day, more or less). Is that possible?

Thanks.

Brian1 12-21-2006 02:21 PM

Not sure what to check from here.

Brian


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