Review request for 6823609

[Xueming Shen]

looks good; approved.

Alan Bateman wrote:
> 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.