The Queue module is primarily used to manage to process large amounts of data on multiple threads. It supports the creation of a new queue object that can take a distinct number of items.
The get() and put() methods are used to add or remove items from a queue respectively. Below is the list of operations that are used to manage Queue:
- get(): It is used to add an item to a queue.
- put(): It is used to remove an item from a queue.
- qsize(): It is used to find the number of items in a queue.
- empty(): It returns a boolean value depending upon whether the queue is empty or not.
- full(): It returns a boolean value depending upon whether the queue is full or not.
A Priority Queue is an extension of the queue with the following properties:
- An element with high priority is dequeued before an element with low priority.
- If two elements have the same priority, they are served according to their order in the queue.
Below is a code example explaining the process of creating multi-threaded priority queue:
Example:
import queueimport threadingimport time  thread_exit_Flag = 0  class sample_Thread (threading.Thread):   def __init__(self, threadID, name, q):      threading.Thread.__init__(self)      self.threadID = threadID      self.name = name      self.q = q   def run(self):      print ("initializing " + self.name)      process_data(self.name, self.q)      print ("Exiting " + self.name)  # helper function to process data        def process_data(threadName, q):   while not thread_exit_Flag:      queueLock.acquire()      if not workQueue.empty():         data = q.get()         queueLock.release()         print ("% s processing % s" % (threadName, data))      else:         queueLock.release()         time.sleep(1)  thread_list = ["Thread-1", "Thread-2", "Thread-3"]name_list = ["A", "B", "C", "D", "E"]queueLock = threading.Lock()workQueue = queue.Queue(10)threads = []threadID = 1  # Create new threadsfor thread_name in thread_list:   thread = sample_Thread(threadID, thread_name, workQueue)   thread.start()   threads.append(thread)   threadID += 1  # Fill the queuequeueLock.acquire()for items in name_list:   workQueue.put(items)  queueLock.release()  # Wait for the queue to emptywhile not workQueue.empty():   pass  # Notify threads it's time to exitthread_exit_Flag = 1  # Wait for all threads to completefor t in threads:   t.join()print ("Exit Main Thread") |
Output:
initializing Thread-1 initializing Thread-2initializing Thread-3 Thread-2 processing AThread-3 processing B Thread-3 processing C Thread-3 processing D Thread-2 processing E Exiting Thread-2 Exiting Thread-1 Exiting Thread-3 Exit Main Thread
Note: The output may differ depending upon the device specifications and processing power.
