[Bug 1100343] [NEW] Error on some forked thread termination in python threading module

[Charles R. Harwood]

Public bug reported:

I'd like for the fix to python issue 14308 to be ported to python2.7 in Ubuntu Precise.
http://bugs.python.org/issue14308

As near as I can tell, it affects python 2.7 threading.Thread threads
which have were are created, call currentThread(), are then forked, and
then terminate.

For my purposes, it is affecting some code I wrote which does spawns
processes to run simple shell scripts in the background.  It also seems
to have affected various Django projects as well as Duplicity as per
https://bugs.launchpad.net/duplicity/+bug/946993.  As I read that
ticket, it was fixed via a workaround in Duplicity/Debbugs?  It seems to
me that this is really a Python2.7 bug.

I was able to easily reproduce this bug with this small test case as per the python bug ticket on Ubuntu Precise Server:
<code>
#!/usr/bin/python
import os
import thread
import threading
import time

def t():
    threading.currentThread() # Populate threading._active with a DummyThread
    time.sleep(3)

thread.start_new_thread(t, ())
time.sleep(1)

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

os.waitpid(pid, 0)
</code>

The fix is a simple two-line patch to threading.py implemented by the
fix for python bug 14308.  I have also attached that, again from
http://bugs.python.org/issue14308.

As far as I can tell, this has not made its way from upstream to
Precise.  My sincerest apologies if this is reported elsewhere or my
report is somehow inappropriate.

** Affects: python2.7 (Ubuntu)
     Importance: Undecided
         Status: New

** Patch added: "Patch from Python Bug 14308"
   https://bugs.launchpad.net/bugs/1100343/+attachment/3484789/+files/dummythreadafterfork2.patch

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https://bugs.launchpad.net/bugs/1100343

Title:
  Error on some forked thread termination in python threading module

Status in “python2.7” package in Ubuntu:
  New

Bug description:
  I'd like for the fix to python issue 14308 to be ported to python2.7 in Ubuntu Precise.
  http://bugs.python.org/issue14308

  As near as I can tell, it affects python 2.7 threading.Thread threads
  which have were are created, call currentThread(), are then forked,
  and then terminate.

  For my purposes, it is affecting some code I wrote which does spawns
  processes to run simple shell scripts in the background.  It also
  seems to have affected various Django projects as well as Duplicity as
  per https://bugs.launchpad.net/duplicity/+bug/946993.  As I read that
  ticket, it was fixed via a workaround in Duplicity/Debbugs?  It seems
  to me that this is really a Python2.7 bug.

  I was able to easily reproduce this bug with this small test case as per the python bug ticket on Ubuntu Precise Server:
  <code>
  #!/usr/bin/python
  import os
  import thread
  import threading
  import time

  def t():
      threading.currentThread() # Populate threading._active with a DummyThread
      time.sleep(3)

  thread.start_new_thread(t, ())
  time.sleep(1)

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

  os.waitpid(pid, 0)
  </code>

  The fix is a simple two-line patch to threading.py implemented by the
  fix for python bug 14308.  I have also attached that, again from
  http://bugs.python.org/issue14308.

  As far as I can tell, this has not made its way from upstream to
  Precise.  My sincerest apologies if this is reported elsewhere or my
  report is somehow inappropriate.

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