[ruby-core:44059] [ruby-trunk - Bug #6236] WEBrick::HTTPServer swallows Exception

Issue #6236 has been updated by regularfry (Alex Young).


I couldn't see that it was reasonable for WEBrick to expect to handle any of the Exception subclasses that aren't StandardErrors.  This problem is caused precisely because WEBrick tried to handle something it shouldn't have, and I'd expect a similar problem with other Exceptions.

For this immediate problem, yes, `rescue Interrupt` would work just as well.  I think it would be masking a wider issue.  My rule of thumb is that you should `rescue Exception` precisely once in any given program, and *never* in a library. That being said, I'd be interested to see WEBrick code which expects to keep working under a `rescue Exception` but would break under `rescue StandardError`. It may just be that I'm insufficiently imaginative to see where it's useful :-)
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Bug #6236: WEBrick::HTTPServer swallows Exception
https://bugs.ruby-lang.org/issues/6236#change-25589

Author: regularfry (Alex Young)
Status: Open
Priority: Normal
Assignee: 
Category: lib
Target version: 
ruby -v: ruby 2.0.0dev (2012-03-31 trunk 35198) [x86_64-linux]


At the moment when using WEBrick you've always got to remember to define a signal handler to be able to kill the server when you're done with it.  This is annoying and makes it more painful to use than it should be, because if you realise you've forgotten to define a trap("INT") handler after you've started the server, all you can do is kill -9 the process.  This also catches out people learning the library more than it should.  It shouldn't be the web server's job to take over process management, but that's what it ends up doing.

The reason this happens is because webrick/server.rb uses `rescue Exception` around its accept loop.  This is more broad than it should be.  The attached patch replaces this with a `rescue StandardError`, and causes other Exception subclasses to be logged and re-raised.  This makes WEBrick::HTTPServer somewhat more friendly to use at the command-line.

If you Ctrl-c out of a `server.start` loop with this patch applied, you can't restart the server because it leaves internal state lying around, but I think it's still an improvement over the current situation.


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