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Re: concurrent access deadlock

From: Philip Martin <philip_at_codematters.co.uk>
Date: 2002-01-16 18:46:39 CET

cmpilato@collab.net writes:

> Philip Martin <pmartin@uklinux.net> writes:
>
> > The deadlock I reported in
> >
> > http://subversion.tigris.org/servlets/ReadMsg?msgId=42676&listName=dev
> >
> > where two separate working copies commit to the same repository, seems
> > to be easy to reproduce at present. I am building against db-4.0.14 as
> > an experiment, and the script in the mail above now provokes deadlock
> > fairly often. I don't think 4.0.14 is itself the cause of the deadlock
> > as I could sometimes provoke it when using 3.3.11 (but I may be wrong
> > here :-)
>
> Boy, it's been a while since I read this mail from you. Has any new
> progress been made? Is it still easy to reproduce?

It is still completely reproduceable. I have had a look at the
problem but haven't made any progress; I don't really know where to
start as I don't know very much about the Berkely DB environment.

On my machines (dual x86 desktop/single x86 laptop) it is easier to
provoke deadlock using ra_local, it usually occurs within the first
dozen update/commits. Using ra_dav it takes longer, I have seen
hundreds of revisions, but that also locks up.

When ra_local deadlocks, the client hangs (forever I think). Over
ra_dav the client times-out, and then all subsequent repository access
will fail until the repository is recovered.

>
> > I tried running 'db_recover -h repostress/db' but that appears to
> > destroy the database, as a subsequent 'db_stat' produces
> > db_stat: DB_ENV->open: repostress/db: No such file or directory
>
> Just so you know, when using db_recover, it's best to use it with:
>
> db_recover -ve -h <db_path>
>
> That way, it rebuilds the environment (and doesn't "destroy the
> database"). Ben helped me to remember those extra arguments -- around
> here we ask, "Did you run db_recover-dash-very-exciting?"

OK, that works! Thanks.

-- 
Philip
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Received on Sat Oct 21 14:36:56 2006

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