Shutting down the netty server takes long time when using SSLHandler.

[Virat Gohil]

Hi All!

I am facing a small problem shutting down my Netty based server with
~1200 connections.

I am using the ChannelGroup as described in Getting Started guide,
following is the code:

public void stop()
       {
               if(timer!=null)
               {
                       timer.stop();
               }
               if(g!=null && factory!=null)
               {
                        ChannelGroupFuture future = g.close();
                        future.awaitUninterruptibly();
                       if(ch!=null)
                       {
                               ch.unbind();
                       }
                       try {
                               bossExecutor.shutdownNow();
                               workerExecutor.shutdownNow();
                               workerExecutor.awaitTermination(3600,
TimeUnit.SECONDS);
                       bossExecutor.awaitTermination(3600, TimeUnit.SECONDS);
                       } catch (InterruptedException e) {
                               //print the exception
                       }
                       factory.releaseExternalResources();
               }
       }

The execution gets stuck at future.awaitUninterruptibly(); I tried
debugging the issue and found the following:

1. when g.close() is called the channel group creates a hashtable and
creates a new DefaultChannelGroupFuture, which becomes the registered
listener on all these channels.
2. Whenever channel.close() is called, the DefaultChannelGroupFuture
gets called and increments the succes/failure count.
3. if the success+failure count=number of channels in the group, then
the operation is considered finished and the thread waiting on the
defaultchannelgroupfuture is released.

I observed in SSLHandler that Channels.close() is called only if the
received frame was empty and the inbound was finished:
SSLHandler.java:406 (decode())
      if (frame == null && engine.isInboundDone()) {
           synchronized (closeFutures) {
               for (;;) {
                   ChannelFuture future = closeFutures.poll();
                   if (future == null) {
                       break;
                   }
                   Channels.close(ctx, future);
               }
           }
       }
Sometimes, either the frame is not null or inbound is not completed,
this causes the SSLHandler to continue decoding.  This leads in
DefaultChannelGroupFuture.childListener.operationComplete() being
called after a very long time.

What we would prefer to do, is to abandon the incomplete data in
SSLHandler.decode() and close the channel immediately as soon as the
server's shutdown method is called. Please let me know if I am missing
something or if there is another way of achieving a faster shutdown.

Thanks,

Virat