title: Netty app hangs when I try to close a io.netty.channel.Channel using closeFuture()
body: <p>My Netty app hangs when I try to close a io.netty.channel.Channel TCP/IP client connection.</p>
  <p>I do:</p>
  <pre><code>ch.isOpen(); //this is TRUE
  ch.closeFuture().sync(); //never returns
  </code></pre>
  <p>stack trace for the thread calling sync is here.</p>
  <pre><code>JavaFX Application Thread@583, prio=5, in group 'main', status: 'WAIT'
  at java.lang.Object.wait(Object.java:-1)
  at java.lang.Object.wait(Object.java:502)
  at io.netty.util.concurrent.DefaultPromise.await(DefaultPromise.java:260)
  at io.netty.channel.DefaultChannelPromise.await(DefaultChannelPromise.java:129)
  at io.netty.channel.DefaultChannelPromise.await(DefaultChannelPromise.java:28)
  at io.netty.util.concurrent.DefaultPromise.sync(DefaultPromise.java:224)
  at io.netty.channel.DefaultChannelPromise.sync(DefaultChannelPromise.java:117)
  at io.netty.channel.DefaultChannelPromise.sync(DefaultChannelPromise.java:28)
  at MyClient.stop(MyClient.java:46)
  </code></pre>
  <p>Is there something that can prevent a channel from closing?  Can I force it closed another way?</p>