Basic Load Testing

[gogmagog]

My company has been developing a product on top of JBoss/Tomcat for the last six months.

I have a question about a simple load test I'm trying to perform. I have two boxes, running Windows XP Pro, and JBoss-2.4.7_Tomcat-4.0.4.

On the one box, I start up 500 threads, they wait() until everyone is started, and then I launch them all with notifyAll(). Once launched, each thread makes an HTTP request to the server with an XML document in the body.

On the server, I have an echo servlet, that takes the request and echo's the document back to the client... that's it.

Tomcat is configured with:




Can anyone explain why, if I increase the number of client threads beyond about 100, I get a ton of connection refused exceptions? Shouldn't I just see performance degrade, but not see outright connection refusal?

thanks,

Ryan

[joelvogt]

There are a few problems with the jboss 2.4.7 release If I remember correctly. I would strongly advise grabbing the 2.4.8 version and seeing if your problems remain.

[gogmagog]

I've run this with:
JBoss-2.4.4_Tomcat-3.2.3
JBoss-2.4.7_Tomcat-4.0.4
JBoss-2.4.7_Jetty-4.0.4
JBoss-2.4.8_Tomcat-4.0.4

With standalone
Tomcat-4.0.4
Tomcat-4.1.9 Beta

and with Resin

Is this just a limitation of servlet containers?

I had assumed if you set the min_threads=500, then you could receive 500 simultaneous requests.

Resin kinda worked, but only if you ran it a couple of times to warm it up. Standalone Tomcat could handle about 200 requests, but no higher?

Am I missing something here?

Ryan

[pascalpt]

I'm not 100% positive, but I think your problem is Win XP Pro which is not considered a "server OS" by MS and has therefore a limitation on number of concurrent connections.

[gogmagog]

According to the MS website, "connection limit" is the number of different IP addresses that can connect; however, from one box to another, there isn't a fixed limit.

We actually tested this to make sure. We opened a bunch of connections to a servlet that goes to sleep.

Strangely enough, there is a limit of 15 Connections from a box to itself *boggle*

Ryan