Lib/test/test_fork1.py

   1 """This test checks for correct fork() behavior.
   2
   3 We want fork1() semantics -- only the forking thread survives in the
   4 child after a fork().
   5
   6 On some systems (e.g. Solaris without posix threads) we find that all
   7 active threads survive in the child after a fork(); this is an error.
   8
   9 """
  10
  11 import os, sys, time, thread
  12
  13 LONGSLEEP = 2
  14
  15 SHORTSLEEP = 0.5
  16
  17 alive = {}
  18
  19 def f(id):
  20     while 1:
  21         alive[id] = os.getpid()
  22         try:
  23             time.sleep(SHORTSLEEP)
  24         except IOError:
  25             pass
  26
  27 def main():
  28     for i in range(4):
  29         thread.start_new(f, (i,))
  30
  31     time.sleep(LONGSLEEP)
  32
  33     a = alive.keys()
  34     a.sort()
  35     assert a == range(4)
  36
  37     cpid = os.fork()
  38
  39     if cpid == 0:
  40         # Child
  41         time.sleep(LONGSLEEP)
  42         n = 0
  43         pid = os.getpid()
  44         for key in alive.keys():
  45             if alive[key] == pid:
  46                 n = n+1
  47         os._exit(n)
  48     else:
  49         # Parent
  50         spid, status = os.waitpid(cpid, 0)
  51         assert spid == cpid
  52         assert status == 0, "cause = %d, exit = %d" % (status&0xff, status>>8)
  53
  54 main()