I'm using Fedora Core 2, apache 2.0 and postgresql 7.4.6. Recently, the application is slowing down.
You don't say what the application is.
> When I check the process
using "top", sometimes postmaster process time is increasing and the process is never end,
The postmaster is supposed to run all the time - this is called a "daemon" in Unix terms. It is responsible for receiving new connections and handling them. Backends handling queries will look something like:
postgres: richardh lamp [local] idle
This is user richardh on database lamp connecting locally with no query in action.
Now, if the processor-time-used column is increasing rapidly that would be unusual, but it should be running always.
> I think this cause the application slowing down
You haven't provided any convincing evidence of this - not yet.
and sometimes this process make the server slowing down and I have to restart postmaster.
This should not be required. Ever.
Is there somebody who experience the same problem? and what is the solution?
You'll need to work through the following steps:
1. Check there is nothing in the logs (messages/httpd/postgresql) that looks "bad" when the application is slow.
2. Check your configuration settings for apache/postgresql - make sure they are reasonable for the workload. If you're not sure what settings you want for postgresql, perhaps read the performance tuning article here:
http://www.varlena.com/varlena/GeneralBits/Tidbits/index.php
3. Check the output of "vmstat 1" when the server is busy and see what happens as it gets less busy. Especially check the disk i/o readings, as this is frequently the limiting factor in a database system.
Once you have a good idea of what is happening, post again and we'll see how we can help.
--
Richard Huxton
Archonet Ltd
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