threading, how to?
Hi, I am trying to understand how to use threading in Python. I get threading as a concept, but not the implementation. In order to start threading, do you call it as a separate function, which will then be applied to the rest of the code (functions) or do you open threading in each function. This all can probably be answered by 'How python threads different functions'? Hope if somebody can drop me a few lines. I've been trying with different tutorials, but still do not understand. Cheers, Stevan -- http://mail.python.org/mailman/listinfo/python-list
Re: threading, how to?
"akrapus" <[EMAIL PROTECTED]> writes: > Hi, > > I am trying to understand how to use threading in Python. I get > threading as a concept, but not the implementation. > > In order to start threading, do you call it as a separate function, > which will then be applied to the rest of the code (functions) or do > you open threading in each function. This all can probably be answered > by 'How python threads different functions'? Python doesn't automatically thread anything. Threading in Python is manual. The idea is that you run your own function in a separate thread of execution that you create. All the functions that you call from the mentioned function (and those that they call, etc.) will then run in those thread of execution. You can create as many threads (probably up to some limit) as you wish and call either the same function from them, or different functions, depending on your application requirements. -- Sergei. -- http://mail.python.org/mailman/listinfo/python-list
Re: threading, how to?
Thanks for reply. So would it be implemented as follows: Func 1 Func 2 Func 3 Thread for Func 1 Thread for Func 2 Thread for Func 3 Cheers Stevan -- http://mail.python.org/mailman/listinfo/python-list
Re: threading, how to?
akrapus wrote: > Thanks for reply. > > So would it be implemented as follows: > > Func 1 > Func 2 > Func 3 > > Thread for Func 1 > Thread for Func 2 > Thread for Func 3 Could be, but the you woul most probably subclass threading.Thread and override the run-method. However, often it is done like this: def some_threaded_function(): while though_shalt_work(): do_work() for i in xrange(THRAD_NUM): t = threading.Thread(target=some_threaded_function) t.start() Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: threading, how to?
"akrapus" <[EMAIL PROTECTED]> writes: > Thanks for reply. > > So would it be implemented as follows: > > Func 1 > Func 2 > Func 3 > > Thread for Func 1 > Thread for Func 2 > Thread for Func 3 Yes, if you wish to run every of your 3 functions in a separate thread. -- Sergei. -- http://mail.python.org/mailman/listinfo/python-list
Re: threading, how to?
akrapus wrote: > Thanks for reply. > > So would it be implemented as follows: > > Func 1 > Func 2 > Func 3 > > Thread for Func 1 > Thread for Func 2 > Thread for Func 3 > > Cheers > > Stevan Here's how I'm doing it, using the thread module (there's a higher level class-based module: threading, but I'm more comfortable with the simple one): import thread, time class ThreadDemo: def __init__(self): self.data = [] self.lock = thread.allocate_lock() self.alive = False def Start(self): self.alive = True thread.start_new_thread(self.Process, (None,)) def Stop(self): self.alive = False def Process(self, dummy=None): while self.alive: self.lock.acquire() self.data.sort() self.lock.release() time.sleep(0.05) def Add(self, value): self.lock.acquire() self.data.append(value) self.lock.release() >>> from ThreadDemo import ThreadDemo >>> demo = ThreadDemo() >>> demo.Start() >>> demo.Add(1) >>> demo.Add(5) >>> demo.Add(2) >>> demo.data [1, 2, 5] >>> demo.Add(3) >>> demo.data [1, 2, 3, 5] >>> demo.Stop() >>> demo.Add(4) >>> demo.data [1, 2, 3, 5, 4] Use the lock whenever you are going to modify data which is shared between more than one thread. Using time.sleep stops the thread from hogging CPU cycles. You only need to sleep a few milliseconds. The thread will clean itself up as soon as it's function (in this case Process) finishes. The ugly (None,) tuple in the start_new_thread / dummy=None Process parameter are because the start_new_thread function demands a tuple of arguments, even when none are required. see http://www.python.org/doc/current/lib/module-thread.html for more info. Iain -- http://mail.python.org/mailman/listinfo/python-list
Re: threading, how to?
Here's a recipe I used a lot: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65448 -- http://mail.python.org/mailman/listinfo/python-list
Re: threading, how to?
akrapus wrote: > Hi, > > I am trying to understand how to use threading in Python. I get > threading as a concept, but not the implementation. > > In order to start threading, do you call it as a separate function, > which will then be applied to the rest of the code (functions) or do > you open threading in each function. This all can probably be answered > by 'How python threads different functions'? > > Hope if somebody can drop me a few lines. I've been trying with > different tutorials, but still do not understand. > > Cheers, > > Stevan > So, I've played with python threading a fair bit, but if you don't need to delve too far into anything special you can get away with doing things fairly simply using the threading module Basically (and this may be over simplifiied for this example), but you can create a thread() object and basically pass it a function pointer. Then you can control the thread object fairly easily with methods such as start() and join(). So, here's an example of how I might thread a function: #BEGIN Code def funcToThread(): print "I'm a function" myThread = threading.Thread(target=functToThread) #a function name without parens basically yields a function pointer myThread.start() #Performs necessary tasks in order to run this thread #Here might be other stuff in your main thread of execution myThread.join() #say you want to force synchronization at some point #END Code Anyhow, there are more ways to do it and it really depends on your needs as to how far you need to take this. Hope that helps. -carl -- Carl J. Van Arsdall [EMAIL PROTECTED] Build and Release MontaVista Software -- http://mail.python.org/mailman/listinfo/python-list
Re: threading, how to?
Thanks a lot to all of you guys. I think it'll take some time before I grasp it properly... -- http://mail.python.org/mailman/listinfo/python-list
BackgroundCall as Pythonic Thread - Re: threading, how to?
akrapus wrote: > Hi, > > I am trying to understand how to use threading in Python. I get > threading as a concept, but not the implementation. > > In order to start threading, do you call it as a separate function, > which will then be applied to the rest of the code (functions) or do > you open threading in each function. This all can probably be answered > by 'How python threads different functions'? > > Hope if somebody can drop me a few lines. I've been trying with > different tutorials, but still do not understand. It think many Python newcomers have similar questions (and confusion worries about those other answers). Maybe thats because they bought the thread/threading.Thread/Queue stuff and confusion from Java, C++ and that like.( And even encourages that throw-and-pray .join() This recipe offers BackgroundCall, which (example) you can probably understand fuildly within a second: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/491280 Thus, you could forget about the technical term "thread". As you write yoursef "..call it as a separate function..": Thats how (new) Python programmers think naturally ? -robert -- http://mail.python.org/mailman/listinfo/python-list
