Use Sun Java plugin in Firefox for Ubuntu 12.04

Technical, Technology
  1. Download and expand a JRE or JDK using root account.  Record the path, e.g. /usr/lib/jvm/jdk1.6.0_23 (we call it <java path>).
  2. sudo update-alternatives --install "/usr/bin/java" "java" "<java path>/bin/java" 1
  3. mkdir -v ~/.mozilla/plugins (skip this if the directory already exists)
  4. cd ~/.mozilla/plugins
  5. ln -s <java path>/jre/lib/amd64/

Quick Java – PermSize and MaxPermSize

Technical, Technology

“Perm” in these 2 JVM arguments refers to Permanent Generation.

The permanent generation is used to hold reflective of the VM itself such as class objects and method objects. These reflective objects are allocated directly into the permanent generation, and it is sized independently from the other generations. Generally, sizing of this generation can be ignored because the default size is adequate. However, programs that load many classes may need a larger permanent generation.

MaxPermSize defaults to 32m for -client and 64m for -server.

e.g. -XX:PermSize=64m -XX:MaxPermSize=128m