To reframe from confusion i have edited the question:
one.py
import threading count = 5 dev = threading.Thread(name='dev', target=dev,args=(workQueue,count,)) dev.setDaemon(True) dev.start() workQueue = Queue.Queue(10) queueLock.acquire() workQueue.put(word) queueLock.release() count = 3 time.sleep(2) count = 5
but my confusion here is I am able to put and get values from queue between threads but in case of count it does not reflect.
Why is that?
What is point am actually missing here?
class dev ( threading.Thread ): def test(self): while 1: print count print self.EPP_Obj queueLock.acquire() if not self.workQueue.empty(): data = self.workQueue.get() print data queueLock.release() else: queueLock.release() def __init__(self, workQueue, EPP_Obj): threading.Thread.__init__(self) self.workQueue = workQueue self.EPP_Obj = EPP_Obj
Let's start with an example:
The Thread subclass:
import threading class Dev(threading.Thread): def __init__(self, workQueue, queueLock, count): super(Dev, self).__init__() # super() will call Thread.__init__ for you self.workQueue = workQueue self.queueLock= queueLock self.count = count def run(self): # put inside run your loop data = '' while 1: with self.queueLock: if not self.workQueue.empty(): data = self.workQueue.get() print data print self.count if data == 'quit': break
The with statement is a smart way to acquire and release a lock, take a look at the doc.
Now the running code:
import Queue import time work_q = Queue.Queue() # first create your "work object" q_lock = threading.Lock() count = 1 dev = Dev(work_q, q_lock, count) # after instantiate like this your Thread dev.setDaemon(True) dev.start() time.sleep(1) with q_lock: work_q.put('word') # word # 1 time.sleep(1) count = 10 with q_lock: work_q.put('dog') # dog # 1 count = 'foo' with q_lock: work_q.put('quit') # quit # 1 dev.join() # This will prevent the main to exit # while the dev thread is still running
With the code above we have a clear example on how self.count stays unchanged no matter what we do to count.
The reason of this behaviour is that calling:
dev = Dev(work_q, q_lock, count)
or
dev = Dev(work_q, q_lock, 1)
is the same thing.
Arnold Moon Showed you a way to change self.count. Adjusting that to our example:
class Dev(threading.Thread): def __init__(self, workQueue, queueLock, count): super(Dev, self).__init__() self.workQueue = workQueue self.queueLock= queueLock self.count = count def set_count(self, value): self.count = value def run(self): data = '' while 1: with self.queueLock: if not self.workQueue.empty(): data = self.workQueue.get() print data print self.count if data == 'quit': break
Calling set_count in our running code will change the value of self.count:
time.sleep(1) with q_lock: work_q.put('word') # word # 1 time.sleep(1) count = dev.count + 9 dev.set_count(count) with q_lock: work_q.put('dog') # dog # 10 count = 'foo' with q_lock: work_q.put('quit') # quit # 10 dev.join()
I hope this will help you clarify some doubts.
I hope this will help you. I think you don't know which way you need to use. there are some ways for multi-threading in python. i introduce the way which use class. you run below codes. you would understand.
main.py
import stringRepeater import Queue workqueue = Queue.Queue() workqueue.put('test1') workqueue.put('test2') workqueue.put('test3') th = stringRepeater.stringRepeater(workqueue,5) th.start() print '----daemon is on ----' th.setCount(3) workqueue.put('test4') workqueue.put('test5')
stringRepeater.py
import threading class stringRepeater(threading.Thread): def __init__(self, workQueue, count): threading.Thread.__init__(self) self.workQueue = workQueue self.repeatCount = count def run(self): while True: teststring = self.workQueue.get() for i in range(self.repeatCount): print teststring def setCount(self, newcount): self.repeatCount = newcount
