On Mon, 21 Nov 2005, Andrew McMillan wrote:
On Sun, 2005-11-20 at 20:06 -0800, Gary Hoffman wrote:
I've run PHP and PostgreSQL for quite a while and never seen this problem
before. I think it's new, but maybe I never paid attention to it before.
I am frequently running out of connections to the database. Here's a
snippet of my ps -ax
1882 ?? S 0:00.07 postgres: postgres cgssd_members [local] idle
1883 ?? S 0:00.09 postgres: postgres cgssd_members [local] idle
1884 ?? S 0:00.07 postgres: postgres cgssd_members [local] idle
1886 ?? S 0:00.14 postgres: postgres cgssd_members [local] idle
1887 ?? S 0:00.06 postgres: postgres cgssd_members [local] idle
500 std- S 0:01.14 /usr/local/bin/postmaster -D
/usr/local/pgsql/data
501 std- S 0:00.02 postgres: stats buffer process
502 std- S 0:00.21 postgres: stats collector process
As you can see, there are some idle connections that have come in from PHP
on my web pages. I've never seen these before and eventually they build up
and I get an error connecting from the PHP page to the database.
I'm running Apache 1.3.33 on Darwin Kernal 7.9.0 (MacOS X 10.3.9) with PHP
4.3.6 and PostgreSQL 7.4.2.
You will have as many of these as you have apache processes. That's
what persistent connections means!
You can end up with a *lot* more than apache's MaxClients if you open
persistent connections with different connection paramaters... so keep
that in mind if you're connecting to more than one database.
You might look at pgpool. Never used it, but it comes up frequently as a
solution to this...
If you have MaxClients set to (e.g.) 150 in your Apache configuration,
and you actually get to something like that, then the default PostgreSQL
configuration of 100 clients simply won't be enough. You should
increase it to at leas 20-50 more than the MaxClients setting that
Apache has.
You'll be pleased to know that each extra PostgreSQL connection
typically uses less than each additional Apache connection (especially
when you're running PHP et al.) so if you find yourself running out of
RAM you will need to lower the MaxClients setting first.
Regards,
Andrew McMillan.
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