Friday, January 15, 2010

Weblogic slow to start (and slow cryptography) on linux (unix),

This is a doozie.

Weblogic takes many minutes to start on unix.

Note this would also apply for any java process that uses the random number generator such as cryptography.

Turns out Weblogic uses random number generator during start up. Because of the bug in java it reads ‘randomness’ from /dev/random. /dev/random is very good random numbers generators but it is extremely slow. It takes sometimes 10 minutes or more to generate one number. /dev/urandom is not that good, but it is instant.
Java somehow maps /dev/urandom file to /dev/random. That’s why default settings in $JAVA_HOME/jre/lib/security/ are useless.

Possible solutions:
1) Add “” (/dev/urandom does not work) to java parameters.

Worse but working solution is:
2) mv /dev/random /dev/random.ORIG ; ln /dev/urandom /dev/random

3) Best solution is to change $JAVA_HOME/jre/lib/security/
Replace securerandom.source with


This problem does not happen under windows because it uses different implementation of /dev/random.

It takes seconds to start weblogic server now.

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