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Re: [Maria-discuss] Known limitation with TokuDB in Read Free Replication & parallel replication ?


Rich Prohaska <prohaska7@xxxxxxxxx> writes:

> I have tokudb kill query working with parallel replication.  Needed to
> attach the mysql thd pointer to each lock request, and use the thd as a key
> into the pending lock requests to find the one being used by a particular
> thd.  Once found, this lock request is immediately completed with a lock
> timeout result.  Also needed to rearrange the lock wait for code so that
> the callback is called when not holding any tokudb locks.

Ok, sounds great!

> This solves 1 or 10 parallel replication stalls with tokudb.  The remainder
> require the tokudb lock timer to pop.
> The problem is that the parallel replicator attempts to kill the query for
> a mysql slave thread that is waiting for a prior txn to complete.  This
> does not have any effect on tokudb.  The workaround for now is to use an
> extremely small tokudb lock timeout so that the stalls are short.

Hm, that sounds like a problem with the parallel replication code. It should
be normal that a thread needs to be killed in "waiting for prior txn", and
it should work. I will look into this.

Is your latest kill query code on github?


 - Kristian.