Thread running (os.system or popen#)

[johanfo]

BPO	701836
Nosy	@mwhudson, @facundobatista

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2005-05-30.19:29:34.000>
created_at = <Date 2003-03-11.21:46:44.000>
labels = ['interpreter-core']
title = 'Thread running (os.system or popen#)'
updated_at = <Date 2005-05-30.19:29:34.000>
user = 'https://bugs.python.org/johanfo'

bugs.python.org fields:

activity = <Date 2005-05-30.19:29:34.000>
actor = 'facundobatista'
assignee = 'none'
closed = True
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2003-03-11.21:46:44.000>
creator = 'johanfo'
dependencies = []
files = []
hgrepos = []
issue_num = 701836
keywords = []
message_count = 6.0
messages = ['15079', '15080', '15081', '15082', '15083', '15084']
nosy_count = 3.0
nosy_names = ['mwh', 'facundobatista', 'johanfo']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue701836'
versions = ['Python 2.2']

[johanfo]

Bottom line: Some programs may lock up when
spawned from a thread.

>>> import thread, os
>>> thread.start_new_thread(os.system,
("/usr/sbin/ntpdate ifi.uio.no",))

This starts a program "ntpdate" from a Python thread.
Usually this is no problem. Ntpdate, is a simple program
to adjust the clock of the system. However, when
ntpdate is started from a thread it locks up and newer
exits!! With my limited debugging knowledge, it sems
as it hangs in a "poll()" kernel call, however, this could
be misleading. (I used stacktrace -p <pid>)

[mwhudson]

Logged In: YES
user_id=6656

IIRC, threads other than the main thread get a signal mask
that blocks everything. That could be the problem, but I
don't know what to do about it...

What platform are you on? Linux?

[johanfo]

Logged In: YES
user_id=556425

I have verified this bug on both Redhat 8.0 and SuSE 8.1,
linux yes.

Signal is one possible path, filedescriptors another. I read
somwhere that there was some issues with pthreads forking
and filedescriptors. However, this is not my area (too low
level)....

[facundobatista]

Logged In: YES
user_id=752496

Please, could you verify if this problem persists in Python 2.3.4
or 2.4?

If yes, in which version? Can you provide a test case?

If the problem is solved, from which version?

Note that if you fail to answer in one month, I'll close this bug
as "Won't fix".

Thank you!

. Facundo

[facundobatista]

Logged In: YES
user_id=752496

Works ok for me:

Python 2.3.4 (#1, Oct 26 2004, 16:42:40)
[GCC 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)] on linux2
Type "help", "copyright", "credits" or "license" for more
information.
>>> import thread, os
>>> thread.start_new_thread(os.system,("/usr/sbin/ntpdate
ifi.uio.no",))
-1210684496
>>>

[facundobatista]

Logged In: YES
user_id=752496

Deprecated. Reopen only if still happens in 2.3 or newer.

. Facundo