Re: [PERFORM] Sudden crazy high CPU usage

[Michael Paquier]

On Wed, Apr 2, 2014 at 7:16 AM, Andres Freund  wrote:
> On 2014-03-31 19:16:58 +0200, Niels Kristian Schjødt wrote:
>> Yes, I could install "perf", though I'm not familiar with it. What would i 
>> do? :-)
>
> As root:
> perf record -a sleep 5
> perf report > my-nice-perf-report.txt
>
> And then send the my-nice-perf-report.txt file.
>
> Locally it's much nicer to see the output using "perf report" without
> redirect into a file, you'll get an interactive UI.
The Postgres wiki has a page dedicated to perf as well here:
https://wiki.postgresql.org/wiki/Profiling_with_perf

Regards,
-- 
Michael


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Re: [PERFORM] Sudden crazy high CPU usage

[Andres Freund]

On 2014-03-31 19:16:58 +0200, Niels Kristian Schjødt wrote:
> Yes, I could install “perf”, though I’m not familiar with it. What would i 
> do? :-)

As root:
perf record -a sleep 5
perf report > my-nice-perf-report.txt

And then send the my-nice-perf-report.txt file.

Locally it's much nicer to see the output using "perf report" without
redirect into a file, you'll get an interactive UI.

Greetings,

Andres Freund

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 PostgreSQL Development, 24x7 Support, Training & Services


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Re: [PERFORM] Sudden crazy high CPU usage

[Niels Kristian Schjødt]

Sorry, but nothing unusual here either, I have compared the time just before 
with the same time the days before and the throughput pattern is exactly the 
same. No differences.


Den 31/03/2014 kl. 22.01 skrev Will Platnick :

> 
> In New Relic, go back a half hour before the problem started so you can't see 
> that this spike happened and send the same screenshot in. My guess is you 
> have increased activity hitting the DB. Do you have pgbouncer or some kind of 
> connection pooling sitting in front? 198 open server connections could 
> account for an increase in load like you're seeing. Do you have postgresql 
> addon in New Relic to show you how many queries are hitting the system to 
> correlate data to?
> 
> On Mon, Mar 31, 2014 at 1:36 PM, Sergey Konoplev  wrote:
> On Mon, Mar 31, 2014 at 3:25 AM, Niels Kristian Schjødt
>  wrote:
> > I'm running postgresql 9.3 on a production server. An hour ago, out of the 
> > "blue", I ran into an issue I have never encountered before: my server 
> > started to use CPU as crazy. The server is a standard ubuntu 12.04 LTE 
> > installation running only Postgres and Redis.
> >
> > The incident can be seen on the in numbers below:
> >
> > https://s3-eu-west-1.amazonaws.com/autouncle-public/other/cpu.png
> 
> The increase doesn't look so sudden. My guess is that the server got
> some new activity. The advice is to setup the statistics collecting
> script by the link [1] and review the results for a period of hour or
> so. It shows charts of statements by CPU/IO/calls with aggregated
> stats, so you could probably find out more than with pure
> pg_stat_statements.
> 
> [1] 
> https://github.com/grayhemp/pgcookbook/blob/master/statement_statistics_collecting_and_reporting.md
> 
> --
> Kind regards,
> Sergey Konoplev
> PostgreSQL Consultant and DBA
> 
> http://www.linkedin.com/in/grayhemp
> +1 (415) 867-9984, +7 (901) 903-0499, +7 (988) 888-1979
> gray...@gmail.com
> 
> 
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> 

Re: [PERFORM] Sudden crazy high CPU usage

[Will Platnick]

In New Relic, go back a half hour before the problem started so you can't
see that this spike happened and send the same screenshot in. My guess is
you have increased activity hitting the DB. Do you have pgbouncer or some
kind of connection pooling sitting in front? 198 open server connections
could account for an increase in load like you're seeing. Do you have
postgresql addon in New Relic to show you how many queries are hitting the
system to correlate data to?

On Mon, Mar 31, 2014 at 1:36 PM, Sergey Konoplev  wrote:

> On Mon, Mar 31, 2014 at 3:25 AM, Niels Kristian Schjødt
>  wrote:
> > I'm running postgresql 9.3 on a production server. An hour ago, out of
> the "blue", I ran into an issue I have never encountered before: my server
> started to use CPU as crazy. The server is a standard ubuntu 12.04 LTE
> installation running only Postgres and Redis.
> >
> > The incident can be seen on the in numbers below:
> >
> > https://s3-eu-west-1.amazonaws.com/autouncle-public/other/cpu.png
>
> The increase doesn't look so sudden. My guess is that the server got
> some new activity. The advice is to setup the statistics collecting
> script by the link [1] and review the results for a period of hour or
> so. It shows charts of statements by CPU/IO/calls with aggregated
> stats, so you could probably find out more than with pure
> pg_stat_statements.
>
> [1]
> https://github.com/grayhemp/pgcookbook/blob/master/statement_statistics_collecting_and_reporting.md
>
> --
> Kind regards,
> Sergey Konoplev
> PostgreSQL Consultant and DBA
>
> http://www.linkedin.com/in/grayhemp
> +1 (415) 867-9984, +7 (901) 903-0499, +7 (988) 888-1979
> gray...@gmail.com
>
>
> --
> Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
>

Re: [PERFORM] Sudden crazy high CPU usage

[Sergey Konoplev]

On Mon, Mar 31, 2014 at 3:25 AM, Niels Kristian Schjødt
 wrote:
> I'm running postgresql 9.3 on a production server. An hour ago, out of the 
> "blue", I ran into an issue I have never encountered before: my server 
> started to use CPU as crazy. The server is a standard ubuntu 12.04 LTE 
> installation running only Postgres and Redis.
>
> The incident can be seen on the in numbers below:
>
> https://s3-eu-west-1.amazonaws.com/autouncle-public/other/cpu.png

The increase doesn't look so sudden. My guess is that the server got
some new activity. The advice is to setup the statistics collecting
script by the link [1] and review the results for a period of hour or
so. It shows charts of statements by CPU/IO/calls with aggregated
stats, so you could probably find out more than with pure
pg_stat_statements.

[1] 
https://github.com/grayhemp/pgcookbook/blob/master/statement_statistics_collecting_and_reporting.md

-- 
Kind regards,
Sergey Konoplev
PostgreSQL Consultant and DBA

http://www.linkedin.com/in/grayhemp
+1 (415) 867-9984, +7 (901) 903-0499, +7 (988) 888-1979
gray...@gmail.com


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Re: [PERFORM] Sudden crazy high CPU usage

[Niels Kristian Schjødt]

Thanks, I don’t think overheating is an issue, it’s a large dell server, and I 
have checked the historic CPU temperature in the servers control panel, and no 
overheating has shown.

Zone_reclaim_mode is already set to 0 

Den 31/03/2014 kl. 16.50 skrev Scott Marlowe :

> On Mon, Mar 31, 2014 at 8:24 AM, Niels Kristian Schjødt
>  wrote:
>> 
>> Thanks, this seems to persist after a reboot of the server though, and I 
>> have never in my server's 3 months life time experienced anything like it.
> 
> Could it be overheating and therefore throttling the cores?
> 
> Also another thing to look at on large memory machines with > 1 CPU
> socket is zone_reclaim_mode being set to 1. Always set it to 0 on a
> linux machine running postgres.



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Re: [PERFORM] Sudden crazy high CPU usage

[Niels Kristian Schjødt]

Yes, I could install “perf”, though I’m not familiar with it. What would i do? :-)
Niels Kristian SchjødtCo-founder & DeveloperE-Mail: nielskrist...@autouncle.comMobile: 0045 28 73 04 93www.autouncle.comFollow us: Facebook  |  Google+  |  LinkedIn  |  Twitter  Get app for: iPhone & iPad  |  Android

Den 31/03/2014 kl. 16.36 skrev Merlin Moncure :perf

Re: [PERFORM] Sudden crazy high CPU usage

[Scott Marlowe]

On Mon, Mar 31, 2014 at 8:24 AM, Niels Kristian Schjødt
 wrote:
>
> Thanks, this seems to persist after a reboot of the server though, and I have 
> never in my server's 3 months life time experienced anything like it.

Could it be overheating and therefore throttling the cores?

Also another thing to look at on large memory machines with > 1 CPU
socket is zone_reclaim_mode being set to 1. Always set it to 0 on a
linux machine running postgres.


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Re: [PERFORM] Sudden crazy high CPU usage

[Merlin Moncure]

On Mon, Mar 31, 2014 at 9:24 AM, Niels Kristian Schjødt <
nielskrist...@autouncle.com> wrote:

> Thanks, this seems to persist after a reboot of the server though, and I
> have never in my server's 3 months life time experienced anything like it.
>


huh.  Any chance of getting 'perf' installed and running a perf top?

merlin

Re: [PERFORM] Sudden crazy high CPU usage

[Niels Kristian Schjødt]

Thanks, this seems to persist after a reboot of the server though, and I have never in my server’s 3 months life time experienced anything like it.
Niels Kristian SchjødtCo-founder & DeveloperE-Mail: nielskrist...@autouncle.comMobile: 0045 28 73 04 93www.autouncle.comFollow us: Facebook  |  Google+  |  LinkedIn  |  Twitter  Get app for: iPhone & iPad  |  Android

Den 31/03/2014 kl. 15.47 skrev Merlin Moncure :On Mon, Mar 31, 2014 at 5:25 AM, Niels Kristian Schjødt wrote:I'm running postgresql 9.3 on a production server. An hour ago, out of the "blue", I ran into an issue I have never encountered before: my server started to use CPU as crazy. The server is a standard ubuntu 12.04 LTE installation running only Postgres and Redis.The incident can be seen on the in numbers below:https://s3-eu-west-1.amazonaws.com/autouncle-public/other/cpu.pngI imidiatly took a look at pg_stat_activity but nothing in there seemed suspicious. I also had a look at the postgres log, but nothing was in there too. I have pg_stat_statements running, so I reseted that one, and nothing really suspicious occurred in there, expect for the fact, that all queries were taking 100x times longer than usual.I have tried the following with no luck:    * Restart clients connecting to the db    * Restart postgres    * Restart the whole serverI have run memory tests on the server as well, and nothing seems to be wrong.No changes in any software running on the servers has been made within the last 24 hours.The question is: I have a streaming replication server running, which I have now done a failover to, and it runs fine. However I still have no clue why my master suddenly has become so CPU consuming, and how I can debug / trace it further down?Using linux 6? One possible culprit is "Transparent Huge PageCompaction".  It tends to hit severs with a lot of memory, especiallyif they've configured a lot of shared buffers.  Google it a for a lotof info.There may be other issues masquerading as this one but it's the firstthing to rule out.  Symptoms are very high cpu utilization and poorperformance that strikes without warning and then resolves alsowithout warning (typically seconds or minutes after the event).For starters, take a look at the value of:/sys/kernel/mm/redhat_transparent_hugepage/enabledAnd do some due diligence research.merlin

Re: [PERFORM] Sudden crazy high CPU usage

[Merlin Moncure]

On Mon, Mar 31, 2014 at 5:25 AM, Niels Kristian Schjødt
 wrote:
> I'm running postgresql 9.3 on a production server. An hour ago, out of the 
> "blue", I ran into an issue I have never encountered before: my server 
> started to use CPU as crazy. The server is a standard ubuntu 12.04 LTE 
> installation running only Postgres and Redis.
>
> The incident can be seen on the in numbers below:
>
> https://s3-eu-west-1.amazonaws.com/autouncle-public/other/cpu.png
>
> I imidiatly took a look at pg_stat_activity but nothing in there seemed 
> suspicious. I also had a look at the postgres log, but nothing was in there 
> too. I have pg_stat_statements running, so I reseted that one, and nothing 
> really suspicious occurred in there, expect for the fact, that all queries 
> were taking 100x times longer than usual.
>
> I have tried the following with no luck:
>
> * Restart clients connecting to the db
> * Restart postgres
> * Restart the whole server
>
> I have run memory tests on the server as well, and nothing seems to be wrong.
>
> No changes in any software running on the servers has been made within the 
> last 24 hours.
>
> The question is: I have a streaming replication server running, which I have 
> now done a failover to, and it runs fine. However I still have no clue why my 
> master suddenly has become so CPU consuming, and how I can debug / trace it 
> further down?

Using linux 6? One possible culprit is "Transparent Huge Page
Compaction".  It tends to hit severs with a lot of memory, especially
if they've configured a lot of shared buffers.  Google it a for a lot
of info.

There may be other issues masquerading as this one but it's the first
thing to rule out.  Symptoms are very high cpu utilization and poor
performance that strikes without warning and then resolves also
without warning (typically seconds or minutes after the event).

For starters, take a look at the value of:

/sys/kernel/mm/redhat_transparent_hugepage/enabled

And do some due diligence research.

merlin


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[PERFORM] Sudden crazy high CPU usage

[Niels Kristian Schjødt]

I'm running postgresql 9.3 on a production server. An hour ago, out of the 
"blue", I ran into an issue I have never encountered before: my server started 
to use CPU as crazy. The server is a standard ubuntu 12.04 LTE installation 
running only Postgres and Redis.

The incident can be seen on the in numbers below: 

https://s3-eu-west-1.amazonaws.com/autouncle-public/other/cpu.png

I imidiatly took a look at pg_stat_activity but nothing in there seemed 
suspicious. I also had a look at the postgres log, but nothing was in there 
too. I have pg_stat_statements running, so I reseted that one, and nothing 
really suspicious occurred in there, expect for the fact, that all queries were 
taking 100x times longer than usual.

I have tried the following with no luck:

• Restart clients connecting to the db
• Restart postgres
• Restart the whole server

I have run memory tests on the server as well, and nothing seems to be wrong.

No changes in any software running on the servers has been made within the last 
24 hours.

The question is: I have a streaming replication server running, which I have 
now done a failover to, and it runs fine. However I still have no clue why my 
master suddenly has become so CPU consuming, and how I can debug / trace it 
further down?

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