[sheepdog] fix embryonic connection

[Liu Yuan]

On 09/04/2012 03:43 PM, MORITA Kazutaka wrote:
> False timeout is not a problem if we simply retry poll when epoch is
> not incremented?  If it is true, I prefer the first approach.  I guess
> we can handle timeout simply and efficiently like this way without TCP
> keepalive.
> 
> I wonder if it is the right way to go to use TCP keepalive.  To be
> honest, I'm not familiar with TCP keepalive well.  Does it really work
> with hundreds of nodes or under heavy load?  I'm afraid there are
> other problems like this.

Keepalive message is only sent when there isn't any data transfer in the
connection, so most of time, the timer won't be fired on. I have
finished the patch with approach 2 and it works well now. I am going to
post the patch set.

Thanks,
Yuan