Question

I’m writing a servlet, which is executed in Java servlet container (eg, JBoss, Jetty, Tomcat, GlassFish).

What are the reasons for a servlet container to interrupt the thread running my HTTP request handler? Will it do that only when shutting down? Will it do that when the client is not responding?

Is it standardized, or is any container free to do what he wishes?

To clarify, I’m not talking about interrupting new threads that I create, only on the servlet container’s threads my requests are running on. (Although it’ll be interesting if you’ll mention what happens to new threads in the answer).

Answer 1

What are the reasons for a servlet container to interrupt the thread running my HTTP request handler?

That depends on the container itself. It’s indeed not standardized in the servlet specification.

Will it do that only when shutting down?

Seems one of the most obvious reasons. Local tests taught me that at least Tomcat 7.0.22 and Glassfish 3.1.1 will abort all the servlet’s processing immediately without letting them to continue their task. No exceptions will be thrown at that point.

Will it do that when the client is not responding?

Only when the request headers are not fully arrived. There’s a container-specific timeout on the socket connection which is usually 60 seconds. But if the request headers are not fully arrived, then your servlet method won’t be entered anyway. Only if the request headers are fully arrived, then your servlet method will be entered.

Then, inside the servlet method; if the client has supplied a request body (e.g. POST) and your servlet’s code starts reading the request body by for example request.getParameter() or request.getInputStream(), then it will throw IOException when the client has aborted sending the request body at that point. On the other hand, when you write to the response (and flush/commit it), then also an IOException will be thrown when the client aborts the connection at that point. You can if necessary put it in a try-catch, but you can’t do anything more with it than just logging. The usefulness of those loggings is highly quesitonable and will likely only clutter your server logs.