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"""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 threading
import test.support as support
LONGSLEEP = 2
SHORTSLEEP = 0.5
NUM_THREADS = 4
class ForkWait(unittest.TestCase):
def setUp(self):
self._threading_key = support.threading_setup()
self.alive = {}
self.stop = 0
self.threads = []
def tearDown(self):
# Stop threads
self.stop = 1
for thread in self.threads:
thread.join()
thread = None
self.threads.clear()
support.threading_cleanup(*self._threading_key)
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))
def test_wait(self):
for i in range(NUM_THREADS):
thread = threading.Thread(target=self.f, args=(i,))
thread.start()
self.threads.append(thread)
# busy-loop to wait for threads
deadline = time.monotonic() + 10.0
while len(self.alive) < NUM_THREADS:
time.sleep(0.1)
if deadline < time.monotonic():
break
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
self.wait_impl(cpid)
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