Bug reference: 5284
Logged by: azuneko
Email address: azu...@hotmail.com
PostgreSQL version: 8.3.3
Operating system: FreeBSD7.0.2
Description: Postgres CPU 100% and worker took too long to start;
cancelled... Systemdown
Details:
Hello,
I have the following 2 problems.
It would be appreciated if you give me some information such as the way to
avoid them.(Or if those problems are already known and fixed, could you
please tell me what version I should apply.)
1,CPU utilization of postgres reaches 100%.
I excuted "top" command and sometimes found that CPU utilization of postgres
process reached 100% or almost 100%. (This is similar to the problem that
was posted at
http://archives.free.net.ph/message/20081104.074244.6e0dbcde.ja.html.)
What might be the cause?
2. The following warning can be seen in the postgres log.
WARNING: worker took too long to start; cancelled
After this warning firstly appears in the log, the same warining message
seems to be repeated. And if you leave this state as it is, the OS freezes
before long. I guess this event happens because the daemons related to
postgres (such as vacuum and autovacuum) won't release the shared memory and
exclusively keep using it. Am I correct?
Those 2 problems are confirmed to happen at least under the following
conditions;
Software
-OS : FreeBSD 7.0.2
-Postgres version : 8.3.3
Hardware
-Disk configuration : RAID5 (MegaCLI)
-CPU : Xeon2.4
Thank you.
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You haven't really provided us with much detail here, but it kind of
sounds like your system is overloaded.
...Robert
> RAID Card : LSI MegaRAID
> Battery Cache : YES
> write-back Cache : NO
> Software RAID : NO ( Hardware RAID)
The LSI MegaRAID series are, AFAIK, software raid implementations. The
hardware has some BIOS hooks to enable boot-loading, then the OS loads a
driver that does all the real work for the RAID implementation.
... though a quick Google search suggests they may be using that brand
for real RAID hardware too, so without specifying the model number it's
hard to know what your RAID hardware is. The fact that your card has a
BBU tends to confirm they're making real RAID hardware under that name.
It probably doesn't make much difference in this particular case,
though, as disk I/O is unlikely to be part of your issue.
> SAN : NO
> Disk : 7,200rpm SATA 3lot
> Disk : RAID5 3slot
Again it's not the cause of the problem you report, but: Most databases,
and certainly PostgreSQL, perform poorly on RAID 5. In particular,
PostgreSQL really doesn't like having the WAL stored on RAID 5, but
really you're much better off using RAID 10 for all your
database-related storage if you can.
--
Craig Ringer