Version 4 (modified by joshuadf, 10 years ago) (diff)


Local Variable Usage

If need temporary local variable, use the less expensive version, but if you are passing the object around use the concurrent version:

Local only Thread-safe
ArrayList Vector
HashMap Hashtable
StringBuilder StringBuffer

This and other hints are available in the Java Anti-Patterns article.

JVM Options

Here's a way to make the Sun server JVM take some extra time reserving memory (used in MindSeer and some Tomcats):

JAVA_OPTS="-server -Xmx384m -Xms384m -XX:GCTimeLimit=95 -XX:GCTimeRatio=49"

Another problem is webapps using up the perm gen space, see #15; you can increase with

JAVA_OPTS="-XX:PermSize=128m -XX:MaxPermSize=256m"