6395224: (so) SocketChannel writer blocked on large buffer is not preempted by close method (vista)

[Alan Bateman]

The test java/nio/channels/AsyncCloseAndInterrupt.java has been failing 
on Windows for a long time. There are a couple of issues.

The main one is that we can't asynchronously close a SocketChannel if 
there is a thread doing I/O on the channel's socket with a buffer size 
of 128k or more. The issue applies to all versions of Windows from 
Windows Server 2003 to present day. It can only be solved by limiting 
the buffer size to less than 128k. Classic networking doesn't run into 
this because it limits the buffer size to 64k on Windows (that limit 
stems from a long standing Microsoft recommendation to only use buffers 
of 64k or smaller).  While this isn't a great solution it should reduce 
the incidents of WSAENOBUFS that come up periodically with applications 
doing blocking I/O with huge buffers. I hope some day to separate the 
blocking and non-blocking paths so this should confine this to blocking I/O.

The other issues are test related. When testing DatagramChannel it binds 
to a local address but attempts to connect to the loopback address 
(different interface). This is corrected by binding to the loopback 
address. The SocketChannel connect/finishConnect tests need to be able 
to "saturate" the connection backlog, which just isn't feasible on 
Window Server editions (no problem on the consumer editions). It's not 
clear that we can create robust tests for this so for now, these 
sub-tests are skipped on Windows.

I've put the webrev here:
  http://cr.openjdk.java.net/~alanb/6395224/webrev/

Thanks,
Alan.