Related: #3219
Motivation:
ChunkedWriteHandler.flush() does not call ctx.flush() when channel is
not writable. This can be a problem when other handler / non-Netty
thread writes messages simultaneously, because
ChunkedWriteHandler.flush() might have no chance to observe
channel.isWritable() returns true and thus the channel is never flushed.
Modifications:
- Ensure that ChunkedWriteHandler.flush() calls ctx.flush() at least
once.
Result:
A stall connection issue, that occurs when certain combination of
handlers exist in a pipeline, has been fixed. (e.g. SslHandler and
ChunkedWriteHandler)