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From:MARK CALLAGHAN Date:July 3 2008 5:20pm
Subject:mutex contention for the query cache
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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
Thread
mutex contention for the query cacheMARK CALLAGHAN3 Jul
  • Re: mutex contention for the query cacheMARK CALLAGHAN3 Jul
    • Re: mutex contention for the query cacheMARK CALLAGHAN3 Jul
      • RE: mutex contention for the query cacheRick James3 Jul
        • Re: mutex contention for the query cacheMARK CALLAGHAN3 Jul
          • RE: mutex contention for the query cacheRick James3 Jul
            • Re: mutex contention for the query cacheMARK CALLAGHAN3 Jul
              • Re: mutex contention for the query cacheBrian Aker3 Jul
              • Re: mutex contention for the query cacheSergei Golubchik3 Jul
          • Re: mutex contention for the query cacheKonstantin Osipov3 Jul
            • Re: mutex contention for the query cacheBrian Aker3 Jul
              • Re: mutex contention for the query cacheSergey Petrunia3 Jul
                • Re: mutex contention for the query cacheBrian Aker3 Jul
                  • Re: mutex contention for the query cacheSergei Golubchik3 Jul
                    • Re: mutex contention for the query cacheBrian Aker4 Jul
                      • Re: mutex contention for the query cacheJonas Oreland4 Jul
                        • Re: mutex contention for the query cacheSergei Golubchik4 Jul
                          • Re: mutex contention for the query cacheJonas Oreland4 Jul
                            • Re: mutex contention for the query cacheJonas Oreland4 Jul
                              • Re: mutex contention for the query cacheKonstantin Osipov4 Jul
                      • Re: mutex contention for the query cacheMark Leith4 Jul
                      • Re: mutex contention for the query cacheMARK CALLAGHAN4 Jul
                        • Re: mutex contention for the query cacheBrian Aker4 Jul
                          • Re: mutex contention for the query cacheMARK CALLAGHAN5 Jul
                            • Re: mutex contention for the query cacheBrian Aker5 Jul
                            • Re: mutex contention for the query cacheJonas Oreland2 Aug
                              • Re: mutex contention for the query cacheFrazer Clement5 Aug
  • Re: mutex contention for the query cacheKonstantin Osipov3 Jul
  • Re: mutex contention for the query cacheJocelyn Fournier3 Jul
    • RE: mutex contention for the query cacheRick James3 Jul
      • Re: mutex contention for the query cacheJocelyn Fournier3 Jul
        • RE: mutex contention for the query cacheRick James3 Jul
  • Re: mutex contention for the query cacheAntony T Curtis3 Jul