Python Programs - Multithreading - Synchronizing Threads:

• Synchronization

  #!/usr/bin/python
  
  import threading
  import time
  
  class myThread (threading.Thread):
     def __init__(self, threadID, name, counter):
       self.threadID = threadID
       self.name = name
       self.counter = counter
       threading.Thread.__init__(self)
     def run(self):
       print "Starting " + self.name
       # Get lock to synchronize threads
       threadLock.acquire()
       print_time(self.name, self.counter, 3)
       # Free lock to release next thread
       threadLock.release()
  
    def print_time(threadName, delay, counter):
       while counter:
         time.sleep(delay)
         print "%s: %s" % (threadName, time.ctime(time.time()))
         counter -= 1
  
  threadLock = threading.Lock()
  threads = []
  
  # Create new threads
  thread1 = myThread(1, "Thread-1", 1)
  thread2 = myThread(2, "Thread-2", 2)
  
  # Start new Threads
  thread1.start()
  thread2.start()
  
  # Add threads to thread list
  threads.append(thread1)
  threads.append(thread2)
  
  # Wait for all threads to complete
  for t in threads:
     t.join()
  print "Exiting Main Thread"

• Output

  Starting Thread-1
  Starting Thread-2
  Thread01: Thu Jan 22 16:04:38 2009
  Thread01: Thu Jan 22 16:04:39 2009
  Thread01: Thu Jan 22 16:04:40 2009
  Thread02: Thu Jan 22 16:04:42 2009
  Thread02: Thu Jan 22 16:04:44 2009
  Thread02: Thu Jan 22 16:04:46 2009
  Exiting Main Thread