On Thu, May 9, 2013 15:25, Robinson, Eric wrote:
>> > -----Original Message-----
>> > From: Robinson, Eric [mailto:eric.robinson@stripped]
>> > Sent: Thursday, May 09, 2013 1:58 PM
>> > To: mysql@stripped
>> > Subject: Slow Response -- What Does This Sound Like to You?
>> > We have a situation where users complain that the system
>> > freezes for 30-90 seconds. We check the slow query logs and
>> find that
>> > one user issued a complex query that did indeed take 30-90
>> seconds to
>> > complete. However, NO slow queries are recorded for the other 50
>> > users, before, during, or after the freeze. Note that the complex
>> > query in question always shows: "Lock_time: 0".
>> > Q: What conditions could cause single query to lock up a
>> database for
>> > a while for all users (even though it shows "lock time: 0") but no
>> > other slow queries would show in the logs for any other
>> users who are
>> > hitting the database at the same time?
>> > OS: RHEL3 x64
>> > CPU: 8 x 2.9GHz Xeon
>> > RAM: 32GB
>> > Disk: RAID 5 (6 x 512GB SSD)
>> > MySQL: 5.0.95 x64
>> > Engine: MyISAM
>> MyISAM? Or InnoDB?
>> Lock_time perhaps applies only to table locks on MyISAM.
>> SHOW ENGINE InnoDB STATUS;
>> You may find some deadlocks.
>> Is Replication involved?
>> Anyone doing an ALTER?
> MyISAM, no replication involved, and nobody is altering the database. This
> happens whenever people run certain reports.
This may be a dumb question, but have you verified that the applications
do not issue a "Lock TABLES ..."? Either the big one or one of the others.
William R. Mussatto