Topic: Proxy_Pass Max connections to Tomcat

[spdaman]

Hi all,

I need to understand how many threads or max connections will be forwarded from an apache web server to Tomcat server using Proxy_pass AJP.

This is my current configuration

<IfModule event.c>
ServerLimit 25
ThreadLimit 100
StartServers 5
MaxRequestWorkers 2500
MinSpareThreads 75
MaxSpareThreads 5000
ThreadsPerChild 100
MaxConnectionsPerChild 0

ProxyPass / ajp://tomcat01:8009/
ProxyPassReverse / ajp://tomcat01:8009/

The apache documentation states that the maximun number of allowed connections to the backend (tomcat) when using MPM (Event in my case) is controlled by the ThreadsPerChild directive. So the question is will 100 connections be allowed or ThreadsPerChild x ServerLimit = 2500 ??

Please let me know how that works.

[James Blond]

Yepp that is true, how ever effictive you will be able to have some more connections since event empm can reuse the connections and for a exmaple downloading a css files doesn't take long and than the connection is free again. Also KeepAlive with event mpm does a lot. If you have a "newer" apache and can use mod_h2 for http/2 a single browser opens only a single connection and reuses it.

[James Blond]

Yes your calculation is correct. See also https://httpd.apache.org/docs/2.4/en/mod/event.html

[spdaman]

You mention calculation is correct but don't specify which how many will get forward 100 or 2500?

Let me know.

[James Blond]

MaxRequestWorkers 2500