In theory, I'd go with Kwok's recommendation: one Apache with it's own load-balancer, and 3 Tomcats instead of 3 Apaches. However, in the real-world, this would require you to upgrade to Apache 2.0.x with the 'worker' MPM.
We cannot repurpose machines. Three web servers (a fourth one is in the way, don't ask why) are a need for other projects, as Apache servers are shared. And technically, I don't think it is viable either (see previous post).
However, I am worried about what you say about Apache 2.0.x and the 'worker' MPM. Could you please tell me about the real-world inconveniences of having 3/4 Apache 1.3.X with 2/3 tomcats behind?
Yes, for your current config, you need to have your maxProcessors somewhere near 600 to handle peak load. For part two, go to each of your Apache machines and run: $ ps -ef | grep httpd | wc -l
Done that. Very varying, depending on time of day. But we set MaxClients to 200 knowing what we were doing. We used to have 100 and it was not enough. Raised to 150 and still not enough. It was during a peak period, but I don't think we should lower it back.
The problem is that the connection is kept open even if unused, isn't it?Add the numbers together, and subtract three (one for each of the Apache 'controller' processes). If the system has been running for awhile, this should be about the same as the number of connections to your Tomcat server on 8009, since mod_jk holds the connection open (by default) for the lifetime of the Apache child.
I mean: If I do not connect to my web-app, does it start the connections?
Except maybe memory requirement??The threads that are waiting for Apache to talk to them are blocked pending input, so aren't affecting Tomcat's performance in any way.
I think it is CoyoteConnector, but I'd have to check to be sure.Since you are using 4.1.9, I'm assuming that you are using the AjpConnector (instead of the newer CoyoteConnector).
We'll be moving to 4.1.26 as soon as we have time to test our app on it. Stuck on 4.1.9 because of client cert auth problem.
Does that apply to CoyoteConnector? Is it really useful?With the AjpConnector, you can set the attribute 'connectionTimeout=xx-ms"' to have Tomcat drop the connection to Apache after xx milliseconds have gone by without traffic.
For tuning, I like OptimizeIt (but it costs).It helped me once upon a time. But I'm in a different company now.
Yes, I heard of JProbe. Never tested. Any insights? How is it compared to (3 years ago) OptimizeIt?I'm sure that other people will offer there opinions.
Thank you very much for your answer, Bill. I think it was really useful.
Antonio Fiol
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