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Posted by Michael Phillipson on 11/07/76 11:14
Thanks, Philip (and Richard also), for offering your impressions.
Per Philip's suggestion, I ran "ab" (Apache Benchmark) to stress test the
page that loads my persistent connection. Depending on the parameters I set
for ab, I was able to increase the number of connections from my initial 9
to anywhere between 15 and 25. This number varied from one test to
another - even if I left the ab parameters the same. I probably could have
boosted the total connections even further by raising the number of
connections/requests initiated by ab.
So, while I still don't have a rock-solid way to predict just how many
connections will be opened for a given number of users, at least I'm not
stuck at 9 :-) I guess it took using an automated approach to simulating
server load (e.g., "ab") to force Apache to open additional connections to
the database.
Interestingly, I also observed during my testing that some connections
opened by Apache were subsequently closed. So, this seems to answer my
other question re. whether persistent connections stay open forever. I
guess they don't. What seems clear is that Apache decides when to terminate
active connections, not the database.
Thanks again.
Mike
"Philip Hallstrom" <php@philip.pjkh.com> wrote in message
news:20050425135720.L734@wolf.pjkh.com...
>> What I am baffled by is the fact that the total nunber of connections
>> between the web server and my database seems to max out at 9. Why 9?
>> Not
>> that I have a problem with this number. I just want to understand how
>> this
>> limit was reached so that I might predict how the application will
>> perform
>> in a production capacity.
>
> I can't think of a reason it would max out at 9 other than perhaps you
> really don't have more than 9 connections open. My understanding is that
> Apache will open a connection per child, per database connection where a
> connection is made up of the host, user, and database.
>
> How many apache processes are running when you take this measurement?
> There's no gaurantee that each of them will have hit your web app and
> start up there own connection.
>
> You might use something like ab (apache benchmark) to hit a page that
> initiates a persistent connection to see what happens as the number of
> apache processes grows.
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