Re: Slow queries on 4.0.13, FreeBSD 4.8 STABLE, linuxthreads, zawodny blog

[Dan Nelson]

In the last episode (May 23), LS said:
> Thanks for the response! Sorry, I should have put more info in there
> in the first place. The select and update queries you see below are
> operating on two different databases, and the lock times are 0:
> 
> # Time: 030523 17:34:28
> # User@Host: scott[tiger] @  [a.b.c.d]
> # Query_time: 23  Lock_time: 0  Rows_sent: 0  Rows_examined: 0
> update my_big_table set some_flag='Y';
> # User@Host: scott[tiger] @  [a.b.c.d]
> # Query_time: 2  Lock_time: 0  Rows_sent: 0  Rows_examined: 0
> use other_db;
> insert into status (hostname, snapshotTimestamp, m1, m2, total) values
> ('host1','2003-05-23 17:34:26',252049128,1555431424,1782);
> 
> The update takes a while to churn through, which is normal. The
> insert takes 2 seconds to be processed, which is the unusual part.

Hm. that is odd.  If you can catch it in the act, what's the output of
"ps axl | sed -n -e 1p -e /mysqld/p" when this happens?  I'm interested
in the WCHAN column.  A thread truly waiting on I/O will probably be in
the "biord" state.  There might be something else causing that thread
to slow down (I've never used a FreeBSD system with more than 1GB of
RAM).

-- 
	Dan Nelson
	dnelson@stripped