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      1 """This test case provides support for checking forking and wait behavior.
      2 
      3 To test different wait behavior, override the wait_impl method.
      4 
      5 We want fork1() semantics -- only the forking thread survives in the
      6 child after a fork().
      7 
      8 On some systems (e.g. Solaris without posix threads) we find that all
      9 active threads survive in the child after a fork(); this is an error.
     10 
     11 While BeOS doesn't officially support fork and native threading in
     12 the same application, the present example should work just fine.  DC
     13 """
     14 
     15 import os, sys, time, unittest
     16 import test.test_support as test_support
     17 thread = test_support.import_module('thread')
     18 
     19 LONGSLEEP = 2
     20 SHORTSLEEP = 0.5
     21 NUM_THREADS = 4
     22 
     23 class ForkWait(unittest.TestCase):
     24 
     25     def setUp(self):
     26         self.alive = {}
     27         self.stop = 0
     28 
     29     def f(self, id):
     30         while not self.stop:
     31             self.alive[id] = os.getpid()
     32             try:
     33                 time.sleep(SHORTSLEEP)
     34             except IOError:
     35                 pass
     36 
     37     def wait_impl(self, cpid):
     38         for i in range(10):
     39             # waitpid() shouldn't hang, but some of the buildbots seem to hang

     40             # in the forking tests.  This is an attempt to fix the problem.

     41             spid, status = os.waitpid(cpid, os.WNOHANG)
     42             if spid == cpid:
     43                 break
     44             time.sleep(2 * SHORTSLEEP)
     45 
     46         self.assertEqual(spid, cpid)
     47         self.assertEqual(status, 0, "cause = %d, exit = %d" % (status&0xff, status>>8))
     48 
     49     def test_wait(self):
     50         for i in range(NUM_THREADS):
     51             thread.start_new(self.f, (i,))
     52 
     53         time.sleep(LONGSLEEP)
     54 
     55         a = self.alive.keys()
     56         a.sort()
     57         self.assertEqual(a, range(NUM_THREADS))
     58 
     59         prefork_lives = self.alive.copy()
     60 
     61         if sys.platform in ['unixware7']:
     62             cpid = os.fork1()
     63         else:
     64             cpid = os.fork()
     65 
     66         if cpid == 0:
     67             # Child

     68             time.sleep(LONGSLEEP)
     69             n = 0
     70             for key in self.alive:
     71                 if self.alive[key] != prefork_lives[key]:
     72                     n += 1
     73             os._exit(n)
     74         else:
     75             # Parent

     76             self.wait_impl(cpid)
     77             # Tell threads to die

     78             self.stop = 1
     79             time.sleep(2*SHORTSLEEP) # Wait for threads to die

     80