[ python-Bugs-1307798 ] subprocess.Popen locks on Cygwin

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Bugs item #1307798, was opened at 2005-09-29 12:05
Message generated for change (Comment added) made by jacek_poplawski
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Category: Threads
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Jacek Poplawski (jacek_poplawski)
Assigned to: Jason Tishler (jlt63)
Summary: subprocess.Popen locks on Cygwin

Initial Comment:
I have problem running application with
subprocess.Popen, it happens only on Python from Cygwin
or compiled on Cygwin. It works correctly on Linux,
QNX, and Python from Windows installer, it also works
on one version of Python 2.4.0 from Cygwin.

When I run application with shell=True - everything is
OK, but when I run it without it - Popen locks on data
= os.read(errpipe_read, 1048576). 

Using options stdin, stdout, stderr doesn't help.

I can't reproduce it with any simple application,
application I am running is written in C++, multithreaded. 

$ python
Python 2.4.2 (#1, Sep 29 2005, 10:56:12)
[GCC 3.4.4 (cygming special) (gdc 0.12, using dmd
0.125)] on cygwin
Type "help", "copyright", "credits" or "license" for
more information.
>>> import subprocess
>>> subprocess.Popen("./application.exe")
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/local/lib/python2.4/subprocess.py", line
542, in __init__
    errread, errwrite)
  File "/usr/local/lib/python2.4/subprocess.py", line
970, in _execute_child
    data = os.read(errpipe_read, 1048576) # Exceptions
limited to 1 MB
KeyboardInterrupt
>>> subprocess.Popen("./application.exe",shell=True)
<subprocess.Popen object at 0x4dd0ec>


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>Comment By: Jacek Poplawski (jacek_poplawski)
Date: 2005-10-03 09:01

Message:
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user_id=264913

Only version of Python from Cygwin which doesn't lock:

Python 2.4 (#1, Dec  4 2004, 20:10:33)
[GCC 3.3.3 (cygwin special)] on cygwin
Type "help", "copyright", "credits" or "license" for more
information.
>>>

Example of version which locks (compiled by hand):
Python 2.4.2 (#1, Sep 29 2005, 10:56:12)
[GCC 3.4.4 (cygming special) (gdc 0.12, using dmd
0.125)] on cygwin

Or Python 2.4.1 from current Cygwin.

Official versions of Python for Windows also don't lock,
because they use different way to implement
subprocess.Popen, but I can't use such Python - it lacks
some features of Cygwin.

PS. I don't know how to report version of Cygwin, it was
installed just by running setup.exe and downloading packages.

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Comment By: Neal Norwitz (nnorwitz)
Date: 2005-10-02 22:22

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Jacek, are all the failures on cygwin?  Can you report the
version of cygwin on the failing boxes as well as the
version of cygwin on the box that passed the test?

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Comment By: Jacek Poplawski (jacek_poplawski)
Date: 2005-09-30 10:07

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Yes, I can run test_subprocess.py and all 38 tests are OK
(in 15 seconds).
Just like I wrote I can't reproduce that with any simple
command, so maybe problem is that subprocess.Popen locks
_if_ application does something specific - but what?

PS. But I can reproduce that on few different computers with
different Python installations so it is not just
installation problem.

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Comment By: Neal Norwitz (nnorwitz)
Date: 2005-09-30 07:33

Message:
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Jason, any comments?  Is this cygwin specific or a general
subprocess issue?

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Comment By: Peter Åstrand (astrand)
Date: 2005-09-29 21:32

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Does the testsuite test_subprocess.py work correctly on this
platform?

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