Problems persist in KQueueSelectorProvider (Mac) in 7u6 ea

[David M. Lloyd]

We're consistently seeing issues under load on Mac with 
KQueueSelectorProvider.

There are two possibly related symptoms: the KQueueSelectorImpl is going 
into a mode where select() does not block, despite the continued 
emptiness of the selected key set; and FileDispatcherImpl#preClose0 is 
hanging, presumably in dup2(), trying to close a socket.

My current hypothesis that some evil race condition exists and is being 
tripped between kqueue and dup2 (a relatively rare way to close a 
socket, at least until NIO came along I guess).  My thought though is 
that sockets should not be preclosed this way: instead it would be 
better to use shutdown(fd, SHUT_RDWR), which would effectively preclose 
the socket and hopefully dodge this issue.

I'm hopefully going to have time to try out a patch which does this, but 
I'm taking a couple weeks off starting tonight so I may not have time, 
so we shall see.
-- 
- DML