RFR 8145127: VM warning: WaitForMultipleObjects timed out (0) ...

[Ivan Gerasimov]

Hello!

There was a timeout observed in os_windows.cpp at the line
3945           res = WaitForMultipleObjects(MAXIMUM_WAIT_OBJECTS, 
handles, FALSE, EXIT_TIMEOUT);

This means there were more than 64 threads exiting at the same time and 
none of the first 64 threads could make any progress during 5 minutes.
Sigh.

To address this issue I suggest two things:
1)
Increase the size of the queue of exiting threads.
We'll still have to wait for only the first 64 threads, if the queue is 
exhausted.
But the chances we hit this condition are greatly reduced.

2)
Raise process_exiting flag earlier, i.e. before trying to enter the 
critical section.
This should decrease the number of threads, contending for a slot in the 
'handles' array during the process exit.

Additionally, it is proposed to suspend all the threads, but the one 
which raised the flag 'process_exiting'.
It would be important in a case, when two threads are about to call 
exit() concurrently.
Otherwise, a race could be faced, if the first thread is waiting for all 
the registered handles, while the second one skips the critical section 
altogether and calls ::exit().

Build went fine on all platforms.  The JTREG tests from 'hotspot' subset 
all pass.

Would you please help review the proposed fix?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8145127
WEBREV: http://cr.openjdk.java.net/~igerasim/8145127/00/webrev/

Sincerely yours,
Ivan