Python3 queue queue module details

queue introduction

queue is the standard library in python, commonly known as queues.

In python, data are Shared between multiple threads, multiple threads for data exchange, will not be able to ensure the consistency and security of data, so when multiple threads need to exchange data, queue, for queue can perfectly solve the data exchange between threads, the consistency ensure the security of data between threads and.

Note: In python2.x, the module is named Queue

The queue module has three queues and constructors

First in, first out (FIFO) queue for Python queue module. queue. Queue (maxsize)

LIFO is similar to heap, i.e., in and out. queue. LifoQueue (maxsize)

The other is that the lower the priority queue, the lower the priority queue. queue. PriorityQueue (maxsize)

Common methods in the queue module

queue. qsize() returns the size of the queue

queue.empty () returns True if the queue is empty and False if not

queue.full() returns True if the queue is full, and False if not

queue.full corresponds to the size of maxsize

queue.get([block[, timeout]]) gets the queue, immediately pulls out 1 element, timeout timeout time

queue.put(item[, timeout]]) writes to the queue, immediately putting 1 element, timeout timeout time

queue.get_nowait() equivalent to ES79en. get(False)

queue.put_nowait(item) equivalent to ES88en.put (item, False)

queue.join () blocks the calling thread until all the tasks in the queue are processed, which actually means waiting until the queue is empty before doing anything else

queue.task_done () after completing a task, the queue.task_done () function sends a signal to the queue where the task has completed

The code examples

The following code is passed under Python3

Create a queue

import queue
q = queue.Queue()

empty method (returns True if the queue is empty)

import queue
q = queue.Queue()
print(q.empty())
# Output: True

full method (returns True if the queue is full)

import queue
q = queue.Queue(1) # Specify the queue size 
q.put('a')
print(q.full())
# Output: True

put method and get method

import queue
q = queue.Queue()
q.put('a')
q.put('b')
print(q.get())
# Output: a

qsize method (returns the number of elements in the queue)

import queue
q = queue.Queue()
q.put('a')
q.put('b')
print(q.qsize())
# Output: 2

conclusion