Does HttpServletResponse#sendError() ever throw an IOException?

Question

The doc explains that the HttpServletResponse#sendError() method throws an IOException if an input or output exception occurs (DRY ;).

I couldn't find any scenario that makes this method throw that exception, is there any?

Answer 1

HTTP is sent over TCP so you can safely assume that somewhere in the underlying HttpServletRequest and HttpServletResponse there is a SocketInputStream and a SocketOutputStream.

If a user closes their browser or the network goes down client-side or server-side, then the server won't be able to receive requests or send responses. If the disconnection happens while the server was in the process of sendError(), then an IOException will occur while writing to the SocketOutputStream.