Re: 100% cpu usage on some postmaster processes kill the complete database

On 01/03/12 16:41, Paul Dunkler wrote:
> Hi List,
>
> we are currently running a rather large postgresql-installation with approximately 4k Transactions and 50k index scans per second.
>
> In the last days on some times of the day (irregular - 3-4 times a day), some of the postmaster processes are running with 100% cpu usage. That leads to a totally breakdown of the query execution. We see tons of statements which are correctly automatically aborted by our statement_timeout set to 15 seconds. I tried to search, but do not really recognize what the problem could be there...
>
> Some things i have checked:
> - We are not running any bulk jobs or maintenance scripts at this time
> - No system errors in any logs during that slowdowns
> - I/O Performance seems fine. No high IO Wait amount... But IO Write totally drops in that times because it seems that no postgres process can perform any update
>
> I just installed a script, which prints me out the top and ps axf information for facing out the problem. I will post a snippet of the top here:

Combine that with this:
SELECT * FROM pg_stat_activity;

That will let you line up pids from top with active queries.

--
Richard Huxton
Archonet Ltd