Re: User concurrency thresholding: where do I look?

От: Simon Riggs
Тема: Re: User concurrency thresholding: where do I look?
Дата: ,
Msg-id: 1185465076.4190.87.camel@ebony.site
(см: обсуждение, исходный текст)
Ответ на: Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah")
Ответы: Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah")
CLOG Patch  ("Jignesh K. Shah")
Список: pgsql-performance

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User concurrency thresholding: where do I look?  (Josh Berkus, )
 Re: User concurrency thresholding: where do I look?  ("Joshua D. Drake", )
 Re: User concurrency thresholding: where do I look?  (Alvaro Herrera, )
  Re: User concurrency thresholding: where do I look?  (Josh Berkus, )
   Re: User concurrency thresholding: where do I look?  (Tom Lane, )
    Re: User concurrency thresholding: where do I look?  (Alvaro Herrera, )
     Re: User concurrency thresholding: where do I look?  (Tom Lane, )
      Re: User concurrency thresholding: where do I look?  (Josh Berkus, )
       Re: User concurrency thresholding: where do I look?  (Tom Lane, )
        Re: User concurrency thresholding: where do I look?  (Josh Berkus, )
         Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
          Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
          Re: User concurrency thresholding: where do I look?  (Tom Lane, )
           Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
            Re: User concurrency thresholding: where do I look?  (Tom Lane, )
             Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
              Re: User concurrency thresholding: where do I look?  (Tom Lane, )
               Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                 Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                 Re: User concurrency thresholding: where do I look?  (David Boreham, )
                  Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                 Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                  Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                   Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                    Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                     Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                      Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                       Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                      Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                       Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                        Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                        Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                         Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                          Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                           Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                            Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                             Re: User concurrency thresholding: where do I look?  (Tom Lane, )
                              Re: User concurrency thresholding: where do I look?  (Robert Lor, )
                             Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                              Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                               Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                                Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                                 Re: User concurrency thresholding: where do I look?  (Alvaro Herrera, )
                                  Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                                 Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
                                  Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                                  Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                                   Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                                    Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                                  Re: User concurrency thresholding: where do I look?  (Josh Berkus, )
                                   Re: User concurrency thresholding: where do I look?  ("Jignesh K. Shah", )
                              CLOG Patch  ("Jignesh K. Shah", )
                               Re: CLOG Patch  ("Simon Riggs", )
                                Re: CLOG Patch  ("Jignesh K. Shah", )
                                 Re: CLOG Patch  ("Simon Riggs", )
                           Re: User concurrency thresholding: where do I look?  ("Simon Riggs", )
       Re: User concurrency thresholding: where do I look?  (Greg Smith, )
        Re: User concurrency thresholding: where do I look?  (Josh Berkus, )
     Re: User concurrency thresholding: where do I look?  ("Joshua D. Drake", )
    Re: User concurrency thresholding: where do I look?  (Gregory Stark, )
 Re: User concurrency thresholding: where do I look?  (Greg Smith, )

On Thu, 2007-07-26 at 11:27 -0400, Jignesh K. Shah wrote:

> However at 900 Users where the big drop in throughput occurs:
> It gives a different top "consumer" of time:


                postgres`LWLockAcquire+0x1c8
>               postgres`SimpleLruReadPage+0x1ac
>               postgres`TransactionIdGetStatus+0x14
>               postgres`TransactionLogFetch+0x58

TransactionIdGetStatus doesn't directly call SimpleLruReadPage().
Presumably the compiler has been rearranging things??

Looks like you're out of clog buffers. It seems like the clog buffers
aren't big enough to hold clog pages for long enough and the SELECT FOR
SHARE processing is leaving lots of additional read locks that are
increasing the number of clog requests for older xids.

Try the enclosed patch.

--
  Simon Riggs
  EnterpriseDB  http://www.enterprisedb.com

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