Other thread Messenger's thread
lock() connection lock()
send_message() connect
try connection lock() ms_fast_connect()
try lock()
DEAD LOCK
supplement
On Tue, Dec 2, 2014 at 4:27 PM, Haomai Wang <haomaiwang@xxxxxxxxx> wrote:
> Hi Gregoy and Sage,
>
> I'm just writing Messenger's unit tests to ensure that SimpleMessenger
> and AsyncMessenger behavior same and expected.
>
> I think the most unclear thing is the lock rule of fast dispatch. When
> introduced fast dispatch, there exists three methods
> "ms_fast_connect", "ms_fast_accept", "ms_fast_dispatch" will be called
> within Messenger's thread. Because without fast dispatcher all
> messages are delivered from queue to queue, fast path will result in
> potential dead lock I think.
>
> "ms_fast_accept" and "ms_fast_connect" are called with
> "pipe_lock"(Pipe) or "lock"(AsyncConnection). And
> Connection::send_message will called outsider. So it may happen:
>
> Other thread Messenger's thread
> lock() connection lock()
> send_message() connect
> try connection lock() ms_fast_connect()
>
> DEAD LOCK
>
> So I'm not sure whether we have some lock rules whether on caller side
> or ms_fast_connect/accept side. For example, ms_fast_connect/accept
> can't acquire the same lock with send_message?
>
> --
>
> Best Regards,
>
> Wheat
--
Best Regards,
Wheat
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