Re: Can postgresql accept mutliple connections in the same

Neil Conway wrote:

>On Fri, 2004-11-19 at 16:17 +1300, Dru wrote:
>
>
>>Though one of hte developers
>>tells me that sometimes it gets a link resource allocation error on
>>opening connections to the database server which i dont know if that is
>>related.
>>
>>
>
>I'm not sure what you mean by a "link resource allocation error". Can
>you provide the exact error message you get when a connection is
>refused? (Try checking the PostgreSQL logfile.)
>
>
I'll get the developer to write down the exact error when it happens again.
I think he only gets it once or twice a week when using the database
server and grown accustomed to it. I myself when testing the database
server for errors dont get any at all when connections fail when they
shouldnt fail :( .

>>Max connections is set to 500, the webpage for the server code
>>initalises and then closes the connection when its done.
>>
>>
>
>It might be worth considering connection pooling or persistent
>connections, although that shouldn't be related to the specific problem
>you're having.
>
>
I was using persistent connections initally and was getting this problem
so switched to non-persistant and made sure i was cleaning them up
afterwards
in case it helped solved this problem. I've replaced the db server and
webserver
also to try and resolve it but that had no effect. I initally thought
it might
be something to do with a kernel limit on sockets or something to that
effect.
These connections are all TCP/IP based.

>>Does pg_dumpall or pg_dump lock the database block access
>>to the database so you cant create connections?
>>
>>
>No.
>
>
Ok that rules out that possibility then.

>>Could it be possible
>>postgresql can only create one connection at a time and if it gets two
>>requests for a connection at the same time it fails?
>>
>>
>
>No.
>
>

Ok rules out that possibility also. Is there any stress testing
software for
postgresql to find out how and when it breaks? I wrote a simple script
to simulate 300 concurrent users on the webfrontend which breaks
the website real quick with 1 in 10 connections to db failing with no error
returned by connect just a dead connection. The website uses php,
the problem could be in the wrapper code for PHP though. I havnt
got much luck asking php developers about the problem though.