From: Date: July 3 2008 8:46pm
Subject: Re: mutex contention for the query cache
List-Archive: http://lists.mysql.com/internals/35783
Message-Id: <20080703184659.GD6626@bodhi>
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* MARK CALLAGHAN <mdcallag@stripped> [08/07/03 21:48]:

> The query cache has a mutex that is locked while it is searched. This
> is not a spin lock, so many threads will go to sleep when there is
> contention. And it is made worse because work is done to create the
> search key in Query_cache::send_result_to_client() (work == memory
> allocation and other byte copying) after the mutex is locked.
> 
> Are there plans to fix this?
> I don't have benchmark results (yet), but I am willing to bet that
> this is a problem.
> 

There are plans. Some work is under way for 6.X (not 6.0).

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