Multiple JVMs vs single app server

Question

I\'m dealing with a system that runs a Java application per customer in its own JVM. We\'ve got about a half dozen dedicated servers that are running close to 100 JVMs total now

Answer 1

There's pros and cons of either approach:

Shared JVM

• Lower overhead - JVM memory footprint (core libraries etc.) only needs to be loaded once.
• Better memory usage. Java processes will consume OS memory for heap space that may not currently be in use.

Separate JVM

• Insulation from 'greedy' or 'leaky' applications.
• Better security from malicious code.
• Easier updates, updating one app without bringing down the other.

Overall, I wouldn't set a blanket policy. Look for small / micro-services or other low-usage apps that may be good candidates to share first and expand from there.