On 6/16/2013 1:51 PM, Ken Brown wrote:
>>      ERRORS
>>        EINTR  The call was interrupted by a signal handler; see
>> signal(7).

I've revised the test case (attached) so that it checks for EINTR.  It 
now runs as expected on Cygwin:

Testing pthread_kill()

Thread 0 starting (0x800102a8)
Thread 1 starting (0x80010348)
Thread 2 starting (0x800103e8)

Sending SIGUSR1 to thread 2 (0x800103e8)
Thread 2 executes signal handler (0x800103e8)
Thread 2 woke up just fine
Sending SIGUSR1 to thread 1 (0x80010348)
Thread 1 executes signal handler (0x80010348)
Thread 1 woke up just fine
Sending SIGUSR1 to thread 0 (0x800102a8)
Thread 0 executes signal handler (0x800102a8)
Thread 0 woke up just fine

So there's no reason to think that a pthread_kill bug is causing the 
problem.  Back to the drawing board.

Ken