Queries appear to timeout and restart

rbunche

I am using php and jpgaph to generate a line graph of statistics on an hourly
basis from a mySQL db. I issue a query for each hour and plot the results.

The problem is that, oftentimes, the queries take minutes to execute. I
noticed that when the query runs for 300 seconds, but is still not complete, and another identical query is launched. I don't know why this should happen or
how (if) I can adjust this apparent timeout.

I have set the php script timeout to 900 seconds which should be enough.

Where is this timeout/restart behavior initiated? Php? MySQL? Are there other
parameters I can tweak so that the query can finish and not be re-issued?

Thanks,
Ralph

[deleted]

Queries are never restarted automatically.

How do you know the query is restarted?

rbunche

Vincent wrote:

Queries are never restarted automatically.

How do you know the query is restarted?

I am monitoring the connections with mysqladmin processlist.
So, I can see that every 300 seconds another query is starting (even
when the others are still running)

rbunche

Ralph Bunche wrote:

Vincent wrote:

Queries are never restarted automatically.

How do you know the query is restarted?

I am monitoring the connections with mysqladmin processlist.
So, I can see that every 300 seconds another query is starting (even
when the others are still running)

In fact, I can use mysqladmin to kill one of the extra queries and it will
be restarted! I just don't know whether this is PHP, Mysql or event Mozilla
that is causing this.

[deleted]

Are you using the crontab?

rbunche

No, I'm not using crontab for this.

Now, I'm suspecting an interation with the max_execution_time parameter
int php.ini. But, even setting that to a large value does not seem to help.

What happend if max_execution_time is exceeded? Can a query be re-issued
in this case?

vincent wrote:

Are you using the crontab?

[deleted]

That's the problem, queries just are not re-issued unless your program somehow does it by itself.

the max_execution_time just stops a script if it takes longer than X seconds, it doesn't re-start anything.

Perhaps there is some javascript or meta-refresh in your page that automatically refreshes the page after X seconds?