Issue1203

This naive program creates 10000 threads. More than 2000 of them are not
executed completely:

-----
import thread, time

cnt_a = cnt_b = 0
def test():
    global cnt_a, cnt_b
    time.sleep(1)
    cnt_a += 1
    time.sleep(1)
    cnt_b += 1

i = 10000
while i:
    i -= 1
    thread.start_new_thread(test, ())

time.sleep(100)
print cnt_a, cnt_b
----

The program prints two different numbers not equal to 10000.

Tested on Linux, Jython2.1, java1.5.0 and Windows, Jython2.5a3, jdk1.6.0_01.

I'd guess that the threads all execute, but because Jython doesn't have
a GIL, several of the increments to cnt_a and cnt_b are stomped on by
other threads.  To make this work properly you can lock around
incrementing the counters, or use
java.util.concurrent.atomic.AtomicInteger instead of plain Python ints.

Confirmed!
By using Locks it works fine.

Thanks for your quick answer!