Another solution to How do I know when a thread quits?

[Giovanni Tumiati]

On Tue, 07 Jun 2005 09:41:16 -0400, Peter Hansen wrote:

On Tue, 07 Jun 2005 06:28:33 -0700, Prashanth  Ellina wrote:

> Hi,
> 
> I have used the low-level thread module to write a multi-threaded app.
> 
> tid = thread.start_new_thread(process, ())
> tid is an integer thread ident.
> 
> the thread takes around 10 seconds to finish processing. Meanwhile the
> main thread finished execution and exits. This causes an error because
> the child thread tries to access something in the sys module which has
> already  been GC'ed.  I want a reliable way of knowing when the child
> thread finished execution so that I can make the main thread wait till
> then.
> 

Prashanth,

By reading the Python documentation I figured out to do the following:

	import threading

	# create an event flag to signal the completion of the thread
	task_event=threading.Event()

	# create thread
	task_thread = threading.Thread\
	(None, name_of_thread_function, None, (thread_args...))
	
	# clear the wait for event flag
	task_event.clear()
	
	while ...:
		# run thread 
		try:
			task_thread.start()
		except:
			task_event.set()
			error_handler()

		if main thread has nothing to do:
			# wait for thread to complete (wait on event flag)
			task_event.wait()
		else:
			if task_event.isSet():
				# thread has completed
			else:
				# thread is still active
				# so main thread can continue with more tasks

	##end while...
		
Remember to have the "task_thread" set the "task_event" flag prior to
completing.

Hope this helps.