Bugs item #846817, was opened at 2003-11-21 19:46
Message generated for change (Comment added) made by mwh
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=846817&group_id=5470
Category: Threads
Group: Python 2.3
Status: Open
Resolution: None
Priority: 5
Submitted By: sheshi sankineni (sheshi)
Assigned to: Nobody/Anonymous (nobody)
Summary: control-c is being sent to child thread rather than main
Initial Comment:
Hi All,
We just migrated from Python-2.2.1 to Python-2.3.1 and
noticed a behavior change with respect to control-c +
threads and importing readline module. We have
developed a CLI (command line interface) to our
hardware using Python (communicating with CORBA).
I am providing you with the code (below) which
demonstrates the changed behavior in Python-2.3.1
with "import readline" & without "import readline" on
Linux
Redhat 7.2. The same program works fine on Python-
2.2.1 with or without importing readline and doing
control-c ALWAYS trapped by the main program.
Any help on this issue will be appreciated
thanks
-sheshi
cli.py
-------
import os
import signal
import sys
import cliEngine
def handleKeyboardInterrupt(signalNumber, frame) :
print 'MAIN THREAD Control-C'
def handleSigUsr1(signalNumber, frame) :
pass
# The main function
if __name__ == '__main__':
try :
# Register a signal handler for ctrl-C, control-z
signal.signal(signal.SIGINT,
handleKeyboardInterrupt)
signal.signal(signal.SIGUSR1, handleSigUsr1)
signal.signal(signal.SIGTSTP, signal.SIG_IGN)
cliEngine.engine = cliEngine.CliEngine()
cliEngine.engine.setPid(os.getpid())
cliEngine.engine.start()
while cliEngine.engine.cliEngineRunning :
signal.pause()
print 'Exiting the main thread'
finally :
pass
cliEngine.py
-----------------
import os
import signal
import sys
import threading
import readline
engine = None
class CliEngine(threading.Thread) :
# Static members of the class
cliEngineRunning = 0
mainThreadPid = 0
def __init__(self) :
threading.Thread.__init__(self)
self.cliEngineRunning = 1
engine = self
def setPid(self, mainPid) :
self.mainThreadPid = mainPid
def run(self) :
print 'calling CliEngine run'
self.cliEngineRunning = 1
self.runEngine()
def runEngine(self) :
while self.cliEngineRunning :
try :
line = raw_input('# ')
if line == "logout" :
self.cliEngineRunning = 0
except KeyboardInterrupt :
print 'CHILD THREAD Control-C
(KeyboardInterrupt)'
except EOFError :
# ctrl-d to logout from CLI
self.cliEngineRunning = 0
except :
print 'Unknown Exception'
self.cliEngineRunning = 0
print 'Returning from cliEngine.runEngine()'
If I remove "import readline" in the above file, control-c
is always trapped by the main thread (cli.py) as shown
by the output below
>>python cli.py
calling CliEngine run
# MAIN THREAD Control-C
# MAIN THREAD Control-C
# logout
Returning from cliEngine.runEngine()
Exiting the main thread
If in the above Python file (cliEngine.py), If I
include "import readline", control-c will be trapped by
the child thread (CliEngine) instead of the main thread,
as shown by the output below and the program
terminates with segmentation fault
>>python cli.py
calling CliEngine run
# CHILD THREAD Control-C (KeyboardInterrupt)
# CHILD THREAD Control-C (KeyboardInterrupt)
#
# logout
Returning from cliEngine.runEngine()
Segmentation fault
----------------------------------------------------------------------
>Comment By: Michael Hudson (mwh)
Date: 2005-04-07 10:14
Message:
Logged In: YES
user_id=6656
Is this still an issue with Python 2.4?
----------------------------------------------------------------------
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=846817&group_id=5470
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