Hey everyone,
I hope one of you can help me with this. This is my first foray into
multi-threaded programming. I have tried to boil my code down to it's
simplest demonstrative form.
My program runs interactively by allowing the user to directly
interact with the python prompt. This program has a runAll() method
that runs a series of subprocesses with a cap on how many instances
are running at a time. My intent is to allow the user to use Ctrl-C to
break these subprocesses. Note that while not reflected in the demo
below, each subprocess needs to be able to run clean-up code before
shutting down (in single-threaded mode I just wrap in try-finally).
When I run DB.py, and interrupt it with Ctrl-C, things do not run so
cleanly. Please let me know what I can change to make this work
properly. My intent is to have the following output:
'key interrupt 1'
'key interrupt 2'
'key interrupt 3'
'key interrupt 4'
'********* stopped midway ********'
Here is the code for a demo:
##############################################################################
DB.py (run this):
##############################################################################
#!/usr/bin/env python
from subprocess import Popen
from threading import Thread, BoundedSemaphore
RUN_PERMISSION = BoundedSemaphore(3)
def runSingle(i):
with RUN_PERMISSION:
Popen(['./Sub.py', str(i)]).wait()
def runAll():
workers = [ Thread(target = runSingle, args = [i])
for i in xrange(RUN_PERMISSION._initial_value + 1) ]
try:
for w in workers:
w.start()
except KeyboardInterrupt:
## This should be shown on a KeyboardInterrupt
print '********* stopped midway ********'
for w in workers:
w.join()
runAll()
##############################################################################
Sub.py (called by DB.py):
##############################################################################
#!/usr/bin/env python
import sys, time
try:
while True: pass
except KeyboardInterrupt:
print 'key interrupt %s' % sys.argv[1]
raise
##############################################################################
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