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From:Herald van der Breggen Date:January 19 2001 12:44pm
Subject:locks, memory and threads
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I have a problem with mysql 3.23.30-gamma. On the busy days with much 
traffic on t he website, it hapens that suddenly mysql is taking all the 
resources of the machine at very high speed. The swap increases quick, 
the threads increase from about 30 (which is average) to over 70 and if 
we don't stop mysql quickly, the computer stops responding. This happens 
allways in the busiest hours of the day.

We are using mysql as database for a web site and use it in combination 
with Apache::Session, which has a mechanism for locking session info 

At the moment that mysql is taking all the resources, apache is sending 
many concurrent replies (about 45, relatively high), and after stopping 
mysql (which can take long), several GET_LOCK-query appear in the 
slow-query-logfile (about 20).

I have studied the problem several days, but can't find any clues so 
far. I wonder whether the lock-mechanism could be the cause, or could it 
be the consequence of a very very very heave query that never appears in 
the slowlog....

I hope you can give me answers to the following:

   1. is there any known problem with GET_LOCK and RELEASE_LOCK in 
      version 3.23.30 ?
   2. Is the GET_LOCK-mechanism the most suitable one to use with 
      Apache::Session ?
   3. Do you have any idea's what the problem could be or how to 
      investigate or how to solve ?
Thanks !
Herald van der Breggen

P.S. I upgraded today to version 3.23.31, so far without problems, but 
the traffic very low at the moment.

locks, memory and threadsHerald van der Breggen19 Jan