[Python-bugs-list] [ python-Bugs-426735 ] [Linux] Threaded Python program hangs

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Bugs item #426735, was updated on 2001-05-23 12:56
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Category: Python Interpreter Core
Group: Platform-specific
>Status: Closed
>Resolution: Wont Fix
Priority: 5
Submitted By: Jeff Epler (jepler)
Assigned to: Nobody/Anonymous (nobody)
Summary: [Linux] Threaded Python program hangs

Initial Comment:
import thread, os, time
thread.start_new_thread(os._exit, (1,))
time.sleep(1)
print "done"

The program never prints "done".

Python 2.1 (tummy RPM 2.1-4)
RedHat 6.2

strace of the main thread shows:
select(0, NULL, NULL, NULL, {1, 0})     = 0 (Timeout)
rt_sigprocmask(SIG_SETMASK, NULL, [RT_0], 8) = 0
rt_sigsuspend([]
... Python completes the time.sleep() call, and then
hangs waiting something.

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>Comment By: Tim Peters (tim_one)
Date: 2001-05-29 13:16

Message:
Logged In: YES 
user_id=31435

Use thread.exit() to abort a thread.

os._exit() is platform-dependent.  On Linux it exits only 
the thread that invokes it, and if that thread holds the 
global interpreter lock at the time, all other threads will 
hang.  On Windows it kills off the process, and all threads 
ever spawned by the process.  I suspect other Unices behave 
more like Windows than Linux here, but clear docs are hard 
to find.

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Comment By: Tim Peters (tim_one)
Date: 2001-05-28 18:52

Message:
Logged In: YES 
user_id=31435

BTW, it doesn't print "done" for me on Win98 either, and I 
didn't expect it to:  _exit() is a "panic! stop the world!" 
function.

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Comment By: Tim Peters (tim_one)
Date: 2001-05-28 18:47

Message:
Logged In: YES 
user_id=31435

Changed to platform-specific, since it Works For Me on 
Win98SE.  However, I'm not sure what "works" means:  what 
do the Linux docs say _exit should do when called from a 
spawned thread?  Does this program fail the same way if you 
write it in C?  It may have to do with that Python 
implements time.sleep() on Linux via select(), to get fine
(r)-grained resolution.

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