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.
