Tomcat – How many Tomcat instances can one application server handle

tomcat

My network engineer states I am part of a cluster where two apache application servers(512G RAM each) have 142 instances each of Tomcat (of which my company represents 6 each with 2G RAM). This seems like a lot and my latency issues move with the hour of the day – 7AM CST software functions fine, 10AM CST – system slows significantly this slowness continues until 6PM CST. My question is how many Tomcat instances can one application server handle?

Best Answer

It depends. At one end of the scale I have seen a 1GB RAM, 2-core pizza box server handle several thousand concurrent requests with barely a sign that the CPU is actually doing anything. That was a very well written application. At the other end, I have seen rack after rack of fairly expensive servers (16GB+ RAM, 4+ cores) handling traffic for a site because the app is so badly written if a server has to handle more than 5 concurrent requests the app falls over.

All that said, it certainly sounds like you have a capacity issue.

If it is memory related then the JVMs may start swapping and that will slow them down to a crawl.

My guess is that it is CPU related. It isn't hard for a badly written app to burn through a huge amount of CPU with very few requests.

There is a chance it is network related. With that many instances you might be serving enough content to saturate the network but I'd expect a different failure mode (e.g. dropped connections) rather than general slowness.

Related Solutions

Tomcat – How to deploy a ClickOnce application via Tomcat

ClickOnce is just a static file, prepared in a specified format. The clickonce file uses a special MimeType mapping, namely

application/x-ms-application

To configure this in tomcat, either in the $TOMCAT/conf/web.xml or the web context,

<mime-mapping>
   <extension>application</extension>
   <mime-type>application/x-ms-application</mime-type>
</mime-mapping>

Alternatively, if you use Apache in front of Tomcat to accelerate static files, you can add the mime type mapping like this in the /etc/httpd/conf/httpd.conf file

AddType application/x-ms-application .application

Linux – Tomcat instances startup

The best way under linux is with a standard SysV Init script. That is the way daemons are supposed to be started under linux so that is the first place most sys admins will look.

Standards are good like that. ;)

Many distros ship with a skeleton startup script which you can modify to suit and some ship with a library of shell functions which you can source to help you write a startup script e.g. on redhat there's /etc/init.d/functions.

You might just use it to call the standard startup script that comes with Tomcat. Tomcat may even come with a SysV init script, I can't recall, it's been ages since I installed vanilla tomcat.

Make your startup script chkconfig-able too!

Best Answer

Related Solutions

Tomcat – How to deploy a ClickOnce application via Tomcat

Linux – Tomcat instances startup

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