| 1 | """This test checks for correct fork() behavior.
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| 2 | """
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| 3 |
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| 4 | import imp
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| 5 | import os
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| 6 | import signal
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| 7 | import sys
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| 8 | import time
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| 9 |
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| 10 | from test.fork_wait import ForkWait
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| 11 | from test.test_support import run_unittest, reap_children, get_attribute, import_module
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| 12 | threading = import_module('threading')
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| 13 |
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| 14 | #Skip test if fork does not exist.
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| 15 | get_attribute(os, 'fork')
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| 16 |
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| 17 |
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| 18 | class ForkTest(ForkWait):
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| 19 | def wait_impl(self, cpid):
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| 20 | for i in range(10):
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| 21 | # waitpid() shouldn't hang, but some of the buildbots seem to hang
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| 22 | # in the forking tests. This is an attempt to fix the problem.
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| 23 | spid, status = os.waitpid(cpid, os.WNOHANG)
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| 24 | if spid == cpid:
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| 25 | break
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| 26 | time.sleep(1.0)
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| 27 |
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| 28 | self.assertEqual(spid, cpid)
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| 29 | self.assertEqual(status, 0, "cause = %d, exit = %d" % (status&0xff, status>>8))
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| 30 |
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| 31 | def test_import_lock_fork(self):
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| 32 | import_started = threading.Event()
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| 33 | fake_module_name = "fake test module"
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| 34 | partial_module = "partial"
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| 35 | complete_module = "complete"
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| 36 | def importer():
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| 37 | imp.acquire_lock()
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| 38 | sys.modules[fake_module_name] = partial_module
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| 39 | import_started.set()
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| 40 | time.sleep(0.01) # Give the other thread time to try and acquire.
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| 41 | sys.modules[fake_module_name] = complete_module
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| 42 | imp.release_lock()
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| 43 | t = threading.Thread(target=importer)
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| 44 | t.start()
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| 45 | import_started.wait()
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| 46 | pid = os.fork()
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| 47 | try:
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| 48 | if not pid:
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| 49 | m = __import__(fake_module_name)
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| 50 | if m == complete_module:
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| 51 | os._exit(0)
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| 52 | else:
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| 53 | os._exit(1)
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| 54 | else:
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| 55 | t.join()
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| 56 | # Exitcode 1 means the child got a partial module (bad.) No
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| 57 | # exitcode (but a hang, which manifests as 'got pid 0')
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| 58 | # means the child deadlocked (also bad.)
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| 59 | self.wait_impl(pid)
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| 60 | finally:
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| 61 | try:
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| 62 | os.kill(pid, signal.SIGKILL)
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| 63 | except OSError:
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| 64 | pass
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| 65 |
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| 66 | def test_main():
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| 67 | run_unittest(ForkTest)
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| 68 | reap_children()
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| 69 |
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| 70 | if __name__ == "__main__":
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| 71 | test_main()
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