On Thu, Apr 30, 2020 at 4:15 PM Amit Kapila <amit.kapil...@gmail.com> wrote:

> On Wed, Apr 29, 2020 at 6:11 PM Suraj Kharage
> <suraj.khar...@enterprisedb.com> wrote:
> >
> > Hi,
> >
> > We at EnterpriseDB did some performance testing around this parallel
> backup to check how this is beneficial and below are the results. In this
> testing, we run the backup -
> > 1) Without Asif’s patch
> > 2) With Asif’s patch and combination of workers 1,2,4,8.
> >
> > We run those test on two setup
> >
> > 1) Client and Server both on the same machine (Local backups)
> >
> > 2) Client and server on a different machine (remote backups)
> >
> >
> > Machine details:
> >
> > 1: Server (on which local backups performed and used as server for
> remote backups)
> >
> > 2: Client (Used as a client for remote backups)
> >
> >
> ...
> >
> >
> > Client & Server on the same machine, the result shows around 50%
> improvement in parallel run with worker 4 and 8.  We don’t see the huge
> performance improvement with more workers been added.
> >
> >
> > Whereas, when the client and server on a different machine, we don’t see
> any major benefit in performance.  This testing result matches the testing
> results posted by David Zhang up thread.
> >
> >
> >
> > We ran the test for 100GB backup with parallel worker 4 to see the CPU
> usage and other information. What we noticed is that server is consuming
> the CPU almost 100% whole the time and pg_stat_activity shows that server
> is busy with ClientWrite most of the time.
> >
> >
>
> Was this for a setup where the client and server were on the same
> machine or where the client was on a different machine?  If it was for
> the case where both are on the same machine, then ideally, we should
> see ClientRead events in a similar proportion?
>

In the particular setup, the client and server were on different machines.


> During an offlist discussion with Robert, he pointed out that current
> basebackup's code doesn't account for the wait event for the reading
> of files which can change what pg_stat_activity shows?  Can you please
> apply his latest patch to improve basebackup.c's code [1] which will
> take care of that waitevent before getting the data again?
>
> [1] -
> https://www.postgresql.org/message-id/CA%2BTgmobBw-3573vMosGj06r72ajHsYeKtksT_oTxH8XvTL7DxA%40mail.gmail.com
>


Sure, we can try out this and do a similar run to collect the
pg_stat_activity output.


> --
> With Regards,
> Amit Kapila.
> EnterpriseDB: http://www.enterprisedb.com
>
>
>

-- 
Rushabh Lathia

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