I'm encountering a situation (in the HEAD code) where I get a deadlock when i disconnect from a QFJ acceptor running on Linux or Mac OS X from a Windows machine.
I can reproduce this using the sample executor/banai applications, so i don't think that it has anything to do with my application code.

Repro:
Run the executor app on a Mac machine
Setup Banzai to connect from a Windows machine to the acceptor on a Mac or a Linux box. this has to be a separate box, not localhost. VMWare Windows -> Linux host works.

The first time the connection will go through successfully. Now, press Ctrl-C to disconnect the Banzai process - the "acceptor" side registers the disconnect messages:
<20070726-02:30:40, FIX.4.0:EXEC->BANZAI, event> (Responding to logon request)
Jul 25, 2007 7:30:43 PM quickfix.mina.AbstractIoHandler exceptionCaught
SEVERE: socket exception (/10.1.9.204:1747): Connection reset by peer
<20070726-02:30:43, FIX.4.4:EXEC->BANZAI, event> (Disconnecting)

Now, try connecting Banzai again. on the Banzai side, you see the logon initiation messages:
<20070726-02:33:10, FIX.4.1:BANZAI->EXEC, event> (Initiated logon request)
<20070726-02:33:10, FIX.4.4:BANZAI->EXEC, outgoing> (8=FIX.4.4☺9=66☺35=A☺34=14☺4
9=BANZAI☺52=20070726-02:33:10.312☺56=EXEC☺98=0☺108=30☺10=007☺)

On the 2nd try, when you see Banzai trying to log on, there are no messages showing up on the Executor side. Doing a Ctrl-\ to get a stack trace yields the following:

"SocketAcceptorIoProcessor-0.0" prio=10 tid=0x905e1800 nid=0x2e7f in Object.wait() [0x8ffad000..0x8ffadf30]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0xb1de2338> (a org.apache.mina.common.support.DefaultCloseFuture)
        at java.lang.Object.wait(Object.java:485)
        at org.apache.mina.common.support.DefaultIoFuture.join(DefaultIoFuture.java:86)
        - locked <0xb1de2338> (a org.apache.mina.common.support.DefaultCloseFuture)
        at quickfix.mina.IoSessionResponder.disconnect(IoSessionResponder.java:44)
        at quickfix.Session.disconnect(Session.java:1369)
        at quickfix.mina.AbstractIoHandler.exceptionCaught(AbstractIoHandler.java:82)
        at org.apache.mina.common.support.AbstractIoFilterChain$TailFilter.exceptionCaught(AbstractIoFilterChain.java:695)
        at org.apache.mina.common.support.AbstractIoFilterChain.callNextExceptionCaught(AbstractIoFilterChain.java:423)
        at org.apache.mina.common.support.AbstractIoFilterChain.access$1100(AbstractIoFilterChain.java:54)
        at org.apache.mina.common.support.AbstractIoFilterChain$EntryImpl$1.exceptionCaught(AbstractIoFilterChain.java:794)
        at org.apache.mina.common.IoFilterAdapter.exceptionCaught(IoFilterAdapter.java:78)
        at org.apache.mina.common.support.AbstractIoFilterChain.callNextExceptionCaught(AbstractIoFilterChain.java:423)
        at org.apache.mina.common.support.AbstractIoFilterChain.access$1100(AbstractIoFilterChain.java:54)
        at org.apache.mina.common.support.AbstractIoFilterChain$EntryImpl$1.exceptionCaught(AbstractIoFilterChain.java:794)
        at org.apache.mina.common.support.AbstractIoFilterChain$HeadFilter.exceptionCaught(AbstractIoFilterChain.java:611)
        at org.apache.mina.common.support.AbstractIoFilterChain.callNextExceptionCaught(AbstractIoFilterChain.java:423)
        at org.apache.mina.common.support.AbstractIoFilterChain.fireExceptionCaught(AbstractIoFilterChain.java:407)
        at org.apache.mina.transport.socket.nio.SocketIoProcessor.read(SocketIoProcessor.java:293)
        at org.apache.mina.transport.socket.nio.SocketIoProcessor.process(SocketIoProcessor.java:241)
        at org.apache.mina.transport.socket.nio.SocketIoProcessor.access$500(SocketIoProcessor.java:44)
        at org.apache.mina.transport.socket.nio.SocketIoProcessor$Worker.run(SocketIoProcessor.java:563)
        at org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:43)
        at java.lang.Thread.run(Thread.java:619)

When you run this on a vanilla Quickfix/J-1.2.1 distribution everything works. However, it starts breaking using the head (as of 709) revision.
Linux->Mac and Linux->linux works, it seems that only when you enter Windows into the equation it starts to misbehave.

I'm inclined to think this is a QFJ and not a MINA issue, since it works fine with 1.2.1 but not with SVN revision.
Also, i've tried various versions of MINA - 1.0.3, 1.0.4 and 1.1.1, and the app still deadlocks in the same way.

I've looked at the code, and it seems that there are 2 different code paths that happen.
When a non-Windows initiator disconnects, the xxx.mina.xxx.DefaultCloseFuture.setValue() is hit, after which we get into the quickfix.mina.IoSessionResponder.disconnect() and sail right through the close().join() code.
However, with a Windows iniatiator, we go straight into the IoSessionResponder, and it seems that the close0() function is never hit so we never mark the future as closing and hang as a result.

I saw something related in https://issues.apache.org/jira/browse/DIRMINA-261 but since we are not specifying SO_LINGER (or SocketLinger) i don't think it applies. i tried setting SocketLinger to be 0, but that didn't change the behaviour.

I can reproduce this consistently, so would like any advice on how to go about further debugging or fixing this.