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From "Christopher L. Shannon (JIRA)" <>
Subject [jira] [Commented] (AMQ-6414) The nio+ssl transports can block and hang on connection in certain situations
Date Thu, 01 Sep 2016 15:44:21 GMT


Christopher L. Shannon commented on AMQ-6414:

I will let CI run and make sure all of the tests are still good and then close this out and
backport the fix to 5.14.x.

> The nio+ssl transports can block and hang on connection in certain situations
> -----------------------------------------------------------------------------
>                 Key: AMQ-6414
>                 URL:
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker, Transport
>    Affects Versions: 5.14.0
>            Reporter: Christopher L. Shannon
>            Assignee: Christopher L. Shannon
> The nio+ssl transports can hang on initial connection and never read from the socket
after the SSL handshake for certain conditions.  This behavior is most evident when using
the auto+nio+ssl transport for a network bridge between 2 brokers, however I also saw the
issue for the normal nio+ssl transport when running the NetworkAsyncStartTest and even the
amqp+nio+ssl transport.
> After debugging I found that the issue is that the onSelect method of the registered
callback, which calls the serviceRead() method, is not always getting triggered.  I believe
that the root of the problem is that even though a selector is registered with a SelectionKey.OP_READ,
there is no guarantee that the selected set is correct which is what the SelectorWorker uses
to detect if the operation is ready. The SelectionKey documentation specifically states that
the ready set is a hint but not a guarantee that the channel is ready.  This seems to only
effect the SSL transport (not normal NIO), probably because a read selection was already done
once to unwrap the SSL transport
> More info:
> The fix for this is to trigger the selectRead() after the transport finishes starting
up.  (needs to be in a new thread specifically for OpenWire to allow the wireformat negotiation
to not block on startup).  This will work for the SSL transport specifically since we know
the transport is read to read from the the channel after starting up.  We know this because
the SSL handshake already took place which means we've already read from the channel.

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