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Connection to MySql gets lost

September 13, 2007 - 08:09
Connection to MySql gets lost
al0000
Posts: 11
 Joined: 2006-08-30

Hello,

I have been experiencing the following problem:

Once in a while, php is unable to connect to the MySql server.
Then after a few seconds of minutes, it does connect again.

I'm not sure if it's a PHP issue or a MySql.

I use fcgi for PHP.

Any ideas?

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September 13, 2007 - 08:11
It should be an mysql
al0000
Posts: 11
 Joined: 2006-08-30

It should be an mysql issue.

When php is unable to connct to mysql, i try to connect to mysql using mysql administrator, and i get:

Can't create new thread (errno 12)

Any ideas?


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September 14, 2007 - 23:52
Hi,This seems like a simple
chris
Posts: 407
 Joined: 2006-01-02

Hi,

This seems like a simple problem. It's most likely one of your configuration directives.

 

Check out some of the "research" I did here, on MySQL configuration directives.

These particular articles might help:

http://www.sitebuddy.com/MySQL/thread_cache_size/thread_concurrency

http://www.sitebuddy.com/MySQL/max_allowed_packet/max_connections/Wait_timeout

 

2 main ideas:

1) Remove persistent MySQL connections from your php.ini (even if this works I recommend you see point 2), to determine exactly which resource is limited. It important to have a stable system to know its "weak points").

http://www.sitebuddy.com/PHP/mysql/Persistent/Database/Connections

 

2) You have limited resources.

Two principals here:

2.1) Try to increase the available resources (threads, connections ...etc...)

2.2) Try to decrease the amount of time a resource is allocated (time out type values should be decreased).

Let us know when you find the exact param that fixed your issue.

Good luck.

Chris

 


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September 19, 2007 - 19:08
Chris, Thank you alot for
al0000
Posts: 11
 Joined: 2006-08-30

Chris,

Thank you alot for your informative reply.
I will proceed to your suggestions, and post results on this thread!

Thx
al


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October 27, 2007 - 08:07
Hello again... Getting back
al0000
Posts: 11
 Joined: 2006-08-30

Hello again...

Getting back to this.
Unfortunately i still haven't solved this issue. It appears very often. And as my database grows larger, it appears more often.
I did everything that you suggested, but it just didn't seem to help...

Here's a screenshot from Mysql administrator...

http://img100.imageshack.us/my.php?image=mysqlthreadsdm7.gif

Isn't weird that i have no thread cached?

Thanx!


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October 27, 2007 - 09:00
THat's more like
al0000
Posts: 11
 Joined: 2006-08-30

THat's more like it!

http://img144.imageshack.us/my.php?image=mysqlthreadsgoodsv1.gif

I raised wait_timeout down to 180.

This guy here had a similar issue:

http://jeremy.zawodny.com/blog/archives/000173.html

I will post results


reply

November 6, 2007 - 01:47
Those values seem very high...
chris
Posts: 407
 Joined: 2006-01-02

I have a pretty active Mysql running multiple clients.
Here are the values I currently have:
Threads_cached: 5
Threads_connected: 1
Threads_created: 6
Threads_running: 1

It's also 1:30 am so that explain why those values are so low.

So the basic principal here appears to be:
1) decrease the timeout value
2) increase the thread cache.
Looks like:
wait_timeout=15;
thread_cache_size=40;

work well for him.

Cheers,
Chris


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