cpython: 020260ec44f2 (original) (raw)

Mercurial > cpython

changeset 74074:020260ec44f2

Issue #11867: Make test_mailbox.test_lock_conflict deterministic (and fix a race condition). [#11867]

Charles-François Natali neologix@free.fr
date	Mon, 19 Dec 2011 12:19:52 +0100
parents	6452edbc5f12(current diff)0053b7c68a02(diff)
children	c706f76c9ea8
files	Lib/test/test_mailbox.py
diffstat	1 files changed, 21 insertions(+), 9 deletions(-)[+] [-] Lib/test/test_mailbox.py 30

line wrap: on

line diff

--- a/Lib/test/test_mailbox.py +++ b/Lib/test/test_mailbox.py @@ -17,6 +17,10 @@ try: import fcntl except ImportError: pass +try:

import multiprocessing

+except ImportError:

multiprocessing = None

class TestBase(unittest.TestCase): @@ -993,28 +997,36 @@ class _TestMboxMMDF(TestMailbox): self.assertEqual(contents, f.read()) self._box = self._factory(self._path)

@unittest.skipUnless(hasattr(os, 'fork'), "Test needs fork().")
@unittest.skipUnless(multiprocessing, "Test needs multiprocessing.") def test_lock_conflict(self):

   # Fork off a subprocess that will lock the file for 2 seconds,[](#l1.21)

   # unlock it, and then exit.[](#l1.22)

   if not hasattr(os, 'fork'):[](#l1.23)

```
       return[](#l1.24)
```

   # Fork off a child process that will lock the mailbox temporarily,[](#l1.25)

```
   # unlock it and exit.[](#l1.26)
```

   ready = multiprocessing.Event()[](#l1.27)

   done = multiprocessing.Event()[](#l1.28)

+ pid = os.fork() if pid == 0:

       # In the child, lock the mailbox.[](#l1.32)

       # child[](#l1.33)
       try:[](#l1.34)

           # lock the mailbox, and signal the parent it can proceed[](#l1.35)
           self._box.lock()[](#l1.36)

```
           time.sleep(2)[](#l1.37)
```

```
           ready.set()[](#l1.38)
```

           # wait until the parent is done, and unlock the mailbox[](#l1.40)

           done.wait(5)[](#l1.41)
           self._box.unlock()[](#l1.42)
       finally:[](#l1.43)
           os._exit(0)[](#l1.44)

   # In the parent, sleep a bit to give the child time to acquire[](#l1.46)

```
   # the lock.[](#l1.47)
```
```
   time.sleep(0.5)[](#l1.48)
```

   # In the parent, wait until the child signals it locked the mailbox.[](#l1.49)

   ready.wait(5)[](#l1.50)
   try:[](#l1.51)
       self.assertRaises(mailbox.ExternalClashError,[](#l1.52)
                         self._box.lock)[](#l1.53)
   finally:[](#l1.54)

       # Signal the child it can now release the lock and exit.[](#l1.55)

       done.set()[](#l1.56)
       # Wait for child to exit.  Locking should now succeed.[](#l1.57)
       exited_pid, status = os.waitpid(pid, 0)[](#l1.58)