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RE: Wedged repositories [#6251]

From: Keith Bostic <bostic_at_sleepycat.com>
Date: 2002-07-23 07:14:45 CEST

> Anyhow, I'm CC'ing in Keith Bostic (Hi Keith, hope you don't mind),
> hoping he can shed some light on this*.
> Keith: for the record, one of my repositories locked up one day.
> First I tried to run 'dbrecover -v -h ${REPOS}/db'. This didn't
> unlock my repos. Then I tried 'dbrecover -ve -h ${REPOS}/db' and
> it did unlock my repos. Any ideas?

The two calls to db_recover shouldn't make any difference with
respect to unlocking your repository.

We've been tracking this question as Support Request #6251.

I think we need to first understand why the repository is locking
up. How often does it happen? Can you make it happen at will?

Generally, database environment hangups are caused by a thread
of control exiting holding a Berkeley DB resource locked. This
is a data structure mutex "lock" that I'm talking about, not a
logical database read/write page "lock". The alternative is a
thread of control exiting holding a logical lock, but that
rarely causes a hang, it usually just means the application
slowly grinds to a halt, it doesn't simply hang. Have you ruled
out any possibility of a thread of control dying without having
gracefully released a resource mutex?

If so, the next debugging step is probably to force a core dump
and sending me a stack trace of every thread of control in the
database environment. That should enable us to speculate as to
what might be the underlying cause.


Keith Bostic
Sleepycat Software Inc. bostic@sleepycat.com
118 Tower Rd. +1-781-259-3139
Lincoln, MA 01773 http://www.sleepycat.com

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Received on Tue Jul 23 07:15:15 2002

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