12:07:06 vstinner@apu$ ./python -m test test_itertools -R 3:3 -F -j4
0:00:00 load avg: 0.44 Run tests in parallel using 4 child processes
(...)
0:02:03 load avg: 4.24 [  1] test_itertools passed (2 min 2 sec) -- running: test_itertools (2 min 3 sec), test_itertools (2 min 3 sec), test_itertools (2 min 3 sec)
beginning 6 repetitions
123456
......

0:02:03 load avg: 4.24 [  2/1] test_itertools failed (2 min 3 sec) -- running: test_itertools (2 min 3 sec), test_itertools (2 min 3 sec)
beginning 6 repetitions
123456
......

test_itertools leaked [32, 32, 32] references, sum=96
test_itertools leaked [24, 22, 22] memory blocks, sum=68

Kill <TestWorkerProcess #1 running test=test_itertools pid=159366 time=2 min 3 sec> process group
Kill <TestWorkerProcess #2 running test=test_itertools pid=159586 time=164 ms> process group
Kill <TestWorkerProcess #3 running test=test_itertools pid=159371 time=2 min 3 sec> process group

== Tests result: FAILURE ==

1 test OK.

1 test failed:
    test_itertools

Total duration: 2 min 3 sec
Tests result: FAILURE