Tomcat 8 hung on Ubuntu 16.0.4

Apply the below fix when you have tomcat not starting issues:

Actually, by setting the following in /etc/default/tomcat8, I was fine:
JAVA_OPTS="-Djava.security.egd=file:/dev/./urandom -Djava.awt.headless=true -Xmx1024m -XX:MaxPermSize=512m -XX:+UseConcMarkSweepGC"