20 Avoiding JVM Delays Caused By Random Number Generation

This chapter describes how to avoid Java Virtual Machine (JVM) delays in Oracle Communications Converged Application Server processes for delays caused by random number generation.

Avoiding JVM Delays Caused by Random Number Generation

The library used for random number generation in Sun's JVM relies on /dev/random by default for UNIX platforms. This can potentially block the Converged Application Server process because on some operating systems /dev/random waits for a certain amount of "noise" to be generated on the host machine before returning a result. Although /dev/random is more secure, Oracle recommends using /dev/urandom if the default JVM configuration delays Converged Application Server startup.

To determine if your operating system exhibits this behavior, try displaying a portion of the file from a shell prompt:

head -n 1 /dev/random

If the command returns immediately, you can use /dev/random as the default generator for SUN's JVM. If the command does not return immediately, use these steps to configure the JVM to use /dev/urandom:

1. Open the $JAVA_HOME/jre/lib/security/java.security file in a text editor.

2. Change the line:

   securerandom.source=file:/dev/random
   

   to read:

   securerandom.source=file:/dev/urandom
   

3. Save your change and exit the text editor.