In the following article, we will learn about what is Semaphore (semaphore) in python. Learn about python semaphores and what role Semaphore can play in python programming.
Semaphore(Semaphore)
The mutex only allows one thread to change data at the same time, while Semaphore allows a certain number of threads to change data at the same time. For example, the toilet has 3 What a pit, only 3 people are allowed to go to the toilet at most, and the people behind can only go in after someone comes out.
import threading,time def run(n): semaphore.acquire() time.sleep(1) print("run the thread: %s\n" %n) semaphore.release() if __name__ == '__main__': num= 0 semaphore = threading.BoundedSemaphore(5) #最多允许5个线程同时运行 for i in range(20): t = threading.Thread(target=run,args=(i,)) t.start() while threading.active_count() != 1: pass #print threading.active_count() else: print('----all threads done---') print(num)
Events inter-thread communication
Python provides the Event object for inter-thread communication. It is a signal flag set by the thread. If the signal flag is If true, other threads wait until the signal is touched.
Event object implements a simple thread communication mechanism. It provides setting signals, clearing signals, waiting, etc. for realizing communication between threads.
Usage of Events
event = threading.Event()
##event.wait( )
The wait method of the Event object will execute quickly and complete the return only when the internal signal is true. When the internal signal flag of the Event object is false, the wait method waits until it is true before returning.
event.set()
Use the set() method of Event to set the signal flag inside the Event object to true. The Event object provides the isSet() method to determine the status of its internal signal flags. When using the set() method of the event object, the isSet() method returns true
event.clear()
Using the Event object The clear() method can clear the signal flag inside the Event object, that is, set it to false. When the clear method of Event is used, the isSet() method returns false .
The above is all the content described in this article. This article mainly introduces the relevant knowledge ofpythonSemaphore(Semaphore). I hope you can use the information to understand the above content. . I hope what I have described in this article will be helpful to you and make it easier for you to learn python.
For more related knowledge, please visit thePython tutorial column on the php Chinese website.
The above is the detailed content of What is python Semaphore (semaphore)? (detailed examples). For more information, please follow other related articles on the PHP Chinese website!

本篇文章给大家带来了关于Python的相关知识,其中主要介绍了关于Seaborn的相关问题,包括了数据可视化处理的散点图、折线图、条形图等等内容,下面一起来看一下,希望对大家有帮助。

本篇文章给大家带来了关于Python的相关知识,其中主要介绍了关于进程池与进程锁的相关问题,包括进程池的创建模块,进程池函数等等内容,下面一起来看一下,希望对大家有帮助。

本篇文章给大家带来了关于Python的相关知识,其中主要介绍了关于简历筛选的相关问题,包括了定义 ReadDoc 类用以读取 word 文件以及定义 search_word 函数用以筛选的相关内容,下面一起来看一下,希望对大家有帮助。

VS Code的确是一款非常热门、有强大用户基础的一款开发工具。本文给大家介绍一下10款高效、好用的插件,能够让原本单薄的VS Code如虎添翼,开发效率顿时提升到一个新的阶段。

本篇文章给大家带来了关于Python的相关知识,其中主要介绍了关于数据类型之字符串、数字的相关问题,下面一起来看一下,希望对大家有帮助。

本篇文章给大家带来了关于Python的相关知识,其中主要介绍了关于numpy模块的相关问题,Numpy是Numerical Python extensions的缩写,字面意思是Python数值计算扩展,下面一起来看一下,希望对大家有帮助。

pythn的中文意思是巨蟒、蟒蛇。1989年圣诞节期间,Guido van Rossum在家闲的没事干,为了跟朋友庆祝圣诞节,决定发明一种全新的脚本语言。他很喜欢一个肥皂剧叫Monty Python,所以便把这门语言叫做python。


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

Atom editor mac version download
The most popular open source editor

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft

Dreamweaver CS6
Visual web development tools
