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

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