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Date:      Tue, 10 Feb 2004 16:08:58 -0700 (MST)
From:      "Kris Gale" <kris-fbsd@asn.net>
To:        "David Xu" <davidxu@viatech.com.cn>
Cc:        freebsd-threads@freebsd.org
Subject:   Re: Question about threads [beaver challenge]
Message-ID:  <53632.68.3.131.72.1076454538.squirrel@mail.asn.net>
In-Reply-To: <4029627F.4090602@viatech.com.cn>
References:  <1076398781.b793f9a0dkt@digitalme.com>    <51993.68.3.131.72.1076432061.squirrel@mail.asn.net>    <20040210193240.GA47392@crodrigues.org> <53224.68.3.131.72.1076449765.squirrel@mail.asn.net> <4029627F.4090602@viatech.com.cn>

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> What's the value of your sysctl kern.threads.max_threads_per_proc and
> kern.threads.max_groups_per_proc ? Mysql  heavily uses system scope
> thread.

I set them both to 2500.

Just to reiterate my problem... I wasn't having any problems with
MySQL starting up new threads.  The problem was that MySQL
would slow to a crawl, and then become completely unresponsive.
I capture the number of threads periodically so I can graph it, and
what I would see when MySQL started to slow was that the number
of threads would be about twice what it should have been, given
the load on the web application.  It appeared that threads were
being created, but would hang around forever, or that all of the
queries were backing up.

Attempting to stop and start the MySQL daemon while the client
application (comprised of several hundred httpd processes) was
trying to reconnect would end up crashing the entire OS, causing
the machine to reboot.  This never happened when I was near
the console, and none of the logs contained any crash messages.

Kris



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