Re: PHP Script timing out and MySql using almost all the CPU…

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Author: Joshua Zeidner
Date:  
To: Main PLUG discussion list
Subject: Re: PHP Script timing out and MySql using almost all the CPU and RAM questions
sounds like you have either a MySQl bug or a problem query. Turn on
query logging and get the query that is causing the problem and post
it here.

-jmz

On Wed, Jul 8, 2009 at 12:21 PM, keith smith<> wrote:
>
>
> Hi Everyone,
>
> I do support for an online store.
>
> Last night we were trying to run a report that was taking forever.  It is a lot of data so I expected it to timeout.  The owner says he has successfully run the report before.  I shelled in and found MySql was using 98.3% of the CPU and I think 4.7% of Memory.
>
> I restarted MySql and the load went down to nothing.
>
> While I was in there I noticed we have 513764k of RAM, and we were using almost all of it and we were using some swap as well.
>
> Here is what I just pulled off the system.
>
> top - 11:12:54 up 229 days, 20:08,  3 users,  load average: 0.21, 0.16, 0.07
> Tasks:  80 total,   2 running,  78 sleeping,   0 stopped,   0 zombie
> Cpu(s):  1.0%us,  0.3%sy,  0.0%ni, 95.7%id,  0.0%wa,  3.0%hi,  0.0%si,  0.0%st
> Mem:    513764k total,   506652k used,     7112k free,     4904k buffers
> Swap:  3723784k total,    32276k used,  3691508k free,   311520k cached
>
>
> This raises a number of questions:
>
> 1) What could cause the MySql server to start using so much CPU?  After a restart we ran the report again and the CPU usage was much less.  The report still timed out.
>
> 2) I'm wondering if more RAM would make the system more responsive?  I've seen the benefits of RAM first hand but not in how it would speed up a web server.
>
> 3) The report we were running gave no indication of timing out. I'm wondering how the following PHP.ini directives come into play:
>
> - max_execution_time = 30 : In seconds.  Why would the script appear to keep working?
>
> - max_input_time = 60 : Same question as above.
>
> I'm wondering if setting the memory - ini_set('memory_limit', '64M'); in that app, if that would help much and if I extend the time if that might help - ini_set('max_execution_time',240);  along with ini_set("max_input_time", 240)  ?
>
> Thanks in advance for your help!
>
> ------------------------
> Keith Smith
>
>
>
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