Mnesia deadlock?

Dan Gudmundsson <>
Mon Jan 2 08:58:08 CET 2006


Adam Aquilon writes:
 > Hi there!
 > 
 > Hope someone out there (Klacke, Dan?) understands something about this:
 > We seemed to get a deadlock in Mnesia. All mnesia calls on one of the
 > nodes hung forever.
 > 
 > 
 > Setup:
 > 
 > We have a system running on multiple nodes on a single host.
 > Mnesia version is 4.1.12.

Without further looking at your logs.

Oh No, don't use 4.1.12 (precompiled) and don't use the compiler from
that release, that compiler produced broken code on mnesia_tm which
wrote garbage on the heap (or somewhere else) which could cause really 
strange problems.

Try upgrading compiler, recompile mnesia and try again.

Other than that mnesia have had a couple fixes since 4.1.12 :-) 
it could be worth upgrading to something later.

Nowadays the compiler have an inbuilt beam validator that checks that
the produced code don't have such problems anymore.

/Dan

 > 
 > A cron job runs every minute to backup the Mnesia tables spread across
 > the nodes. (It does this by forking a new beam that does an rpc:call()
 > towards one of the nodes in the running system, and does an
 > mnesia:backup/1.) Admittedly, this is very often, but we only have
 > a small amount of data... :-)

<cut>



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