[ python-Bugs-1431253 ] Logging hangs thread after detaching a StreamHandler's termi

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Bugs item #1431253, was opened at 2006-02-14 06:07
Message generated for change (Settings changed) made by vsajip
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Category: Python Library
Group: Python 2.4
>Status: Pending
>Resolution: Works For Me
Priority: 5
Submitted By: Yang Zhang (yangzhang)
Assigned to: Vinay Sajip (vsajip)
Summary: Logging hangs thread after detaching a StreamHandler's termi

Initial Comment:
Hi all,

After many hours, I think I've found a bug in the 
logging module!

If you add a (stdout) StreamHandler to a logger, then 
detach the terminal for that stdout, subsequent calls 
to log() will hang the calling thread.

To reproduce this, write the following scripts (this 
was a small test case I came up with - maybe there's 
something simpler):

$ cat tryhup.bash
#!/usr/bin/env bash
scp hup.* localhost:
ssh localhost './hup.bash ; while true ; do sleep 1 ; 
done'

$ cat hup.bash
#!/usr/bin/env bash
./hup.py &

$ cat hup.py
#!/usr/bin/env python
import time
import logging
f = file( '/tmp/hup.out', 'w' )
try:
        logging.basicConfig( filename = '/tmp/lup.out', 
filemode = 'w' )
        # XXX PROBLEM LINE BELOW
        logging.getLogger('').addHandler( logging.
StreamHandler() )
        while True:
                f.write( '-------\n' )
                f.flush()
                logging.critical( '======' )
                time.sleep(1)
finally:
        f.close()

Run ./tryhup.bash. It will sit in an idle spin. Monitor 
the files /tmp/hup.out and /tmp/lup.out. Hit Ctrl-C on 
tryhup to kill it. The python process is still running, 
but is stalled (the .out files are no longer changing).

If you remove the above labeled line, however, this 
doesn't happen.

Can anybody please acknowledge this bug? Any temporary 
workarounds to this problem? Thanks in advance for 
looking into this and for hearing me in!

----------------------------------------------------------------------

>Comment By: Vinay Sajip (vsajip)
Date: 2006-02-17 01:04

Message:
Logged In: YES 
user_id=308438

Please provide more information about your OS - I ran these
scripts on Ubuntu 5.10 and did not see the problems you
mention. The script continues to run (printing dashes to the
console), and hup.out/lup.out are also updated continuously. 

Also, note that the logging module merely opens the stream
passed to the StreamHander for output, so check if in
your configuration you get a hang just doing a write to
sys.stderr.

----------------------------------------------------------------------

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