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

[Trustin Lee]

Hi Virat,

On Wed, Apr 15, 2009 at 8:33 PM, Virat Gohil <virat.gohil at gmail.com> wrote:
> 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.

1) What is the state of the actual connection?  Is it closed or still connected?

2) What happens if you replace:

        if (frame == null && engine.isInboundDone()) {
with:

        if (frame == null && engine.isInboundDone() || !channel.isConnected()) {

?

> 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.

You are doing correctly and the ChannelGroupFuture should return
quickly.  Thanks for reporting the problem!

Trustin