java - Calling System.exit() in Servlet's destroy() method

Question

This is a follow up to my earlier question.

Tomcat 5.0.28 had a bug where the Servlet's destroy() method was not being invoked by the container on a shutdown. This is fixed in Tomcat 5.0.30, but if the Servlet's destroy() method had a System.exit(), it would result in the Tomcat windows service throwing the Error 1053 and refusing to shutdown gracefully (see above link for more details on this error)

Anybody has any idea on whether:

• Calling System.exit() inside a Servlet's destroy() method to forcefully kill any non-daemon threads is a good idea?

• Why does Tomcat 5.0.30 and (later versions including Tomcat 6.x.x) fail to shutdown properly if there's a System.exit() in the destroy() method of the Servlet.

Answer 1

Calling System.exit() inside a Servlet's destroy() method to forcefully kill any non-daemon threads is a good idea?

It is absolutely not a good idea - it is a horrible idea. The destroy() method is called when the servlet is taken out of service, which can happen for any number of reasons: the servlet/webapp has been stopped, the webapp is being undeployed, the webapp is being restarted etc.

System.exit() shuts down the entire JVM! Why would you want to forcibly shutdown the entire server simply because one servlet is being unloaded?

Why does Tomcat 5.0.30 and (later versions including Tomcat 6.x.x) fail to shutdown properly if there's a System.exit() in the destroy() method of the Servlet.

Probably to prevent such dangerous behavior like this.

You shouldn't write code that assumes that your code/application is the only thing running on the server.