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Tomcat's scalability

Leon Rosenberg wrote: 
Isn't Tomcat and JVM still single threaded?
Single thread = single processor usage

I don't think it was ever singlethreaded. And if it were, what would
the Connector setting
in the server.xml mean?
  <Connector port="8580" maxHttpHeaderSize="8192"
              maxThreads="750" minSpareThreads="25" maxSpareThreads="75"

Max number of Java thread, IMHO.
Java thread is not the same as operating system thread.
In fact, JVM used to be single threaded on Linux and Windows and I'm not quite sure has it changed recently.
So, you might have 800 Java threads but it is still one thread on operating system.
When you run "ps aux | grep java" you always see one operating system thread IMHO.
It means you don't exploit 4 processors if you have 4.
To exploit 4 processors you have to setup 4 JVM (4 tomcat instances) to do round robin.
As long as you have 1 JVM active you don't exploit thread level parallelism in operating system.

AFAIK

--
Mladen Adamovic
http://www.online-utility.org http://www.shortopedia.com http://www.froola.com http://www.gift-idea4u.com



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