If you have installed Tomcat 8 on your Linux server and it is taking forever to (re)start, it is not your fault. It happens when Java Runtime Environment (JRE) entropy source is short of entropy. Tomcat 8+ relies on
SecureRandom class to provide randomly generated values for its session ids and in other places. JRE can cause delays during startup if entropy source that is used to initialize
SecureRandom is short of entropy.
Note: If you are using Tomcat 9 with Java 11, just install Haveged by typing
sudo apt install havegedin your terminal and you're all good. There is no need to modify JDK security files. It might also work for Tomcat 8 with Java 8 (
nottested and worked).
To fix this issue, you need to replace the blocking entropy source with a non-blocking source in
$JAVA_PATH/jre/lib/security/java.security file. Depending on your installation of Java (headless JRE, Oracle Java, OpenJDK ...),
$JAVA_PATH can be different. In my case (Java 8 OpenJDK on Ubuntu 18.04), it is
$ nano /usr/lib/jvm/java-8-openjdk-amd64/jre/lib/security/java.security
Find the line with
securerandom.source=file:/dev/random text and change it to
securerandom.source=file:/dev/./urandom. Save the file and restart Tomcat 8. That's it.
You can also fix this issue by setting the following system property which will configure the JRE to use a non-blocking entropy source.