cpython/Lib/test/fork_wait.py
2012-12-25 16:47:37 +02:00

78 lines
2.1 KiB
Python

"""This test case provides support for checking forking and wait behavior.
To test different wait behavior, override the wait_impl method.
We want fork1() semantics -- only the forking thread survives in the
child after a fork().
On some systems (e.g. Solaris without posix threads) we find that all
active threads survive in the child after a fork(); this is an error.
"""
import os, sys, time, unittest
import test.support as support
_thread = support.import_module('_thread')
LONGSLEEP = 2
SHORTSLEEP = 0.5
NUM_THREADS = 4
class ForkWait(unittest.TestCase):
def setUp(self):
self.alive = {}
self.stop = 0
def f(self, id):
while not self.stop:
self.alive[id] = os.getpid()
try:
time.sleep(SHORTSLEEP)
except OSError:
pass
def wait_impl(self, cpid):
for i in range(10):
# waitpid() shouldn't hang, but some of the buildbots seem to hang
# in the forking tests. This is an attempt to fix the problem.
spid, status = os.waitpid(cpid, os.WNOHANG)
if spid == cpid:
break
time.sleep(2 * SHORTSLEEP)
self.assertEqual(spid, cpid)
self.assertEqual(status, 0, "cause = %d, exit = %d" % (status&0xff, status>>8))
@support.reap_threads
def test_wait(self):
for i in range(NUM_THREADS):
_thread.start_new(self.f, (i,))
time.sleep(LONGSLEEP)
a = sorted(self.alive.keys())
self.assertEqual(a, list(range(NUM_THREADS)))
prefork_lives = self.alive.copy()
if sys.platform in ['unixware7']:
cpid = os.fork1()
else:
cpid = os.fork()
if cpid == 0:
# Child
time.sleep(LONGSLEEP)
n = 0
for key in self.alive:
if self.alive[key] != prefork_lives[key]:
n += 1
os._exit(n)
else:
# Parent
try:
self.wait_impl(cpid)
finally:
# Tell threads to die
self.stop = 1