Re: Cpu usage 100% on slave. s_lock problem. - Mailing list pgsql-performance

From Merlin Moncure
Subject Re: Cpu usage 100% on slave. s_lock problem.
Date
Msg-id CAHyXU0weAh-qZQ_CCCNoded9wd9WrzVdmnyto_JN+kESjN-1Jw@mail.gmail.com
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In response to Re: Cpu usage 100% on slave. s_lock problem.  (Andres Freund <andres@2ndquadrant.com>)
Responses Re: Cpu usage 100% on slave. s_lock problem.  (Andres Freund <andres@2ndquadrant.com>)
List pgsql-performance
On Tue, Sep 17, 2013 at 6:59 AM, Andres Freund <andres@2ndquadrant.com> wrote:
> Hi,
>
> On 2013-09-17 17:55:01 +0600, Дмитрий Дегтярёв wrote:
>> We have not been able to reproduce this problem on a test servers. Use this
>> patch to production servers do not dare.
>>
>> In the course of studying the problems we have identified that many queries
>> are executed on the slave several times slower. On master function
>> heap_hot_search_buffer execute 100 cycles, on the slave the same query with
>> the same plan function heap_hot_search_buffer execute 2000 cycles.
>> Also, we were able to reproduce the problem on the master and detect that
>> there s_lock of slow queries.
>
> What you describe is normally an indication that you have too many
> longrunning transactions around preventing hot pruning from working.

Do you think it's worth submitting the lock avoidance patch for formal review?

merlin


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