What does the show processlist look like? Have you ran top/vmstat/iostat when the `hanging` occurs?
Hjalmar Gislason wrote:
Hi there,
I've been having some trouble with an application that I'm running (www.spurl.net).
I have a database that consists of about 20 tables. The largest tables are a little more than one million rows and the database in total around 1GB - so nothing serious there. The amount of queries is on average less than 10 per second and it's running on a pretty powerful machine, so all in all there shouldn't really be any performance issues - and normally there aren't. All of the tables are myISAM.
Now, from time to time (even several times per hour) one of my tables seems to "hang" for 30 - 180 seconds, and as this is a key table in the application it basically brings everything to a halt. The interesting thing is that I can not see a pattern in the web server logs of anything special going on at these times.
I have run a "check table" and "analyze table" and everything seems to be fine there.
So my question is pretty general: What can cause a table to hang like that?
Obviously write locks could, but as I said it seems that there is not necessarily any writes or updates going on at the time. And normally (when the server is not in this foul mood) I can run dozens or even hundreds of all my write queries per second. - Can VERY heavy SELECT statements have this effect? - Could it have something to do with indexes (there is only one partial text index on this table in addition to the primary index)? - Could my hosting provider be running some scheduled tasks on the server that cause this? It is a dedicated server and they run backup once a day, which might cause something like this - but that does not go hand in hand with the fact that this happens now and then during the entire day.
Basically I'm looking for ideas for what to look into as I'm running out of ideas (have been rewriting queries, making caches and all sort of things).
As I'm running this in a hosted environment I don't have full access to everything - but at least a place to start would be really heplful.
Thanks in advance, -hjalmar
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