Channel freeze on getCloseFuture() - deadlock?

[Rafael Marins]

Hi Netties,

In the development of my own transport implementation for Netty a test were
created as the code bellow. There are very few circumstances where the
execution simply freeze on channelFuture.getChannel().close() instruction -
it's random. Most of times I run it and get it all okay, but sometimes it
breaks and I must have to stop the execution manually.


    @Test
    public void testChannelConnectAndDisconnect() throws Exception {

        ...
        ClientBootstrap bootstrap = ...

        // CONNECT
        ChannelFuture channelFuture = client.connect(calledAddress,
callingAddress);
        channelFuture.await();

        // DISCONNECT
        ChannelFuture closeFuture = channelFuture.getChannel().close();
        closeFuture.await();

    }


After a deep analysis & debugging I found that the execution freezes when
the framework try to call the AbstractChannel.getCloseFuture() method. It's
invoked from within the Channels.close() method.

When it happens the last logging entry shown is a WRITE_COMPLETE event being
handled by the ChannelSink, then it freezes. I believe that there has such a
deadlock for handling CLOSE_REQUEST concurrently with the WRITE_COMPLETE.

If a Thread.sleep(10) is introduced between the CONNECT and DISCONNECT,
everything goes fine on every execution.

Any clue?

Best regards,

-----
Rafael Marins
Neociclo - http://www.neociclo.com


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