From: Date: July 3 2008 7:20pm Subject: mutex contention for the query cache List-Archive: http://lists.mysql.com/internals/35777 Message-Id: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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. -- Mark Callaghan mdcallag@stripped