We had an odd problem with Mysql the other day (v. 4.0 - RHEL3 up2date).

Our web site stopped responding.
We logged in, and checked our log files.
1.nothing related in /var/log/messages.
2.too late to check dmesg.
3.no problems in the mysql log. There were active queries and looked as
if it were in use and running properly.

I was not around when the problem occured, but i was told that you could
hop into the mysql console, but it froze when you did "use database_name;"

I thought this was odd, as the log files show that the website didn't have
any trouble doing this.

at this point mysql was restarted, and operations resumed as normal.

What type of things should I be looking for to prevent this?

I found why our mysql server crashed the other day.
Mysql gave several errors saying
"060311 10:06:01 Error in accept: Too many open files"

right now mysql has close to 3000 files open, which can vary by a few
hundred to a thousand every second. The entire system has on average about
4000 files open.

I thought this might be a problem, but /proc/sys/fs/file-max says we can
have 209708 files open...

ulimit -a shows this.
open files (-n) 1024

How do i fix this??
Obviously /proc/sys/fs/file-max is not the problem
/proc/sys/fs/file-ng shows "1665 1046 209708"
And that number in ulimit was the problem, would I be having trouble right
now??

Plz, help!

On Mon, 13 Mar 2006 10:48:59 -0500, Arty wrote:
> I found why our mysql server crashed the other day.
> Mysql gave several errors saying
> "060311 10:06:01 Error in accept: Too many open files"
>
> right now mysql has close to 3000 files open, which can vary by a few
> hundred to a thousand every second. The entire system has on average about
> 4000 files open.
>
> I thought this might be a problem, but /proc/sys/fs/file-max says we can
> have 209708 files open...
>
> ulimit -a shows this.
> open files (-n) 1024
>
> How do i fix this??
> Obviously /proc/sys/fs/file-max is not the problem
> /proc/sys/fs/file-ng shows "1665 1046 209708"
> And that number in ulimit was the problem, would I be having trouble right
> now??
>
> Plz, help!

Check the user class restrictions on the user ID that mysqld runs under.
That will probably have a different number than the sustem-wide maximum
of open files.

--
They got rid of it because they judged it more trouble than it was worth.
(And considering they'd gone to great lengths to minimize its worth,
I suppose they were right.)
-- J. D. Baldwin