Review request for 6823609

[Alan Bateman]

6823609: (se) Selector.select hangs on Windows under load

This is a hang in the Windows select-based Selector that has been 
haunting the woods since 1.4.1. This Selector employs a helper thread 
per 1023 registered channels. If the number of required helpers 
decreases and immediately increases then it possible, under load 
conditions, for a redundant helper to poll and finish a cycle instead of 
terminating. This can cause the main Selector thread to wakeup 
prematurely or to hang because the finished thread count goes negative. 
The fix marks redundant threads as zombies so that they terminate 
without interference.

The webrev is here:
  http://cr.openjdk.java.net/~alanb/6823609/webrev.00/

Thanks,
Alan.