Hi Janko,
a user of GNU Smalltalk found a serious bug in Swazoo 2.2. To reproduce
the bug, open any Swazoo page and close the browser. Running netstat
will show sockets in CLOSE_WAIT state. Repeating will show more sockets
in this state.
The problem here is that when the client closes the socket, this
condition is returned by SwazooStream as a SwazooStreamNoDataError
exception; at this point, the stream should be closed on the Swazoo side
too.
However, it is not because of this:
[[ [ [true] whileTrue:
[self getAndDispatchMessages.
Processor yield]
]
on: Error
do: [:ex | "just ignore"] ]
ifCurtailed: [
(Delay forMilliseconds: 50) wait. "to finish sending, if any"
self close] ].
Ignoring the exception causes #getAndDispatchMessages to sit forever
waiting for I/O (not busy waiting, at least on GNU Smalltalk) while the
socket is left open.
I changed this to
[[[true] whileTrue:
[self getAndDispatchMessages.
Processor yield]]
ifCurtailed:
[self close]]
on: Error
do: [:ex |
(Delay forMilliseconds: 50) wait. "to finish sending, if any"
self close]].
and it fixes the bug.
By the way, I'm not sure about the need for those delays either.
There's one here and one in #getAndDispatchMessages. They don't seem to
be necessary on GNU Smalltalk.
Finally, here we're using #on:do: directly rather than the Sport
wrapper. I think we should do this uniformly in Swazoo for this
particular case, since exceptions are now portable and we're relying on
the ANSI #ifCurtailed: message anyway.
Thanks!
Paolo
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