Backend Development
Python Tutorial
Python crawler multi-threading detailed explanation and example code
Python crawler multi-threading detailed explanation and example code
Python supports multi-threading, mainly through the two modules thread and threading. The thread module is a relatively low-level module, and the threading module provides some packaging for thread, making it more convenient to use.
Although python's multi-threading is limited by GIL and is not true multi-threading, it can still significantly improve efficiency for I/O-intensive calculations, such as crawlers.
An example is used below to verify the efficiency of multi-threading. The code only involves page acquisition and does not parse it.
# -*-coding:utf-8 -*- import urllib2, time import threading class MyThread(threading.Thread): def __init__(self, func, args): threading.Thread.__init__(self) self.args = args self.func = func def run(self): apply(self.func, self.args) def open_url(url): request = urllib2.Request(url) html = urllib2.urlopen(request).read() print len(html) return html
if __name__ == '__main__':
# 构造url列表
urlList = []
for p in range(1, 10):
urlList.append('http://s.wanfangdata.com.cn/Paper.aspx?q=%E5%8C%BB%E5%AD%A6&p=' + str(p))
# 一般方式 n_start = time.time() for each in urlList: open_url(each) n_end = time.time() print 'the normal way take %s s' % (n_end-n_start)
# 多线程 t_start = time.time() threadList = [MyThread(open_url, (url,)) for url in urlList] for t in threadList: t.setDaemon(True) t.start() for i in threadList: i.join() t_end = time.time() print 'the thread way take %s s' % (t_end-t_start)
Use two methods to obtain 10 web pages with relatively slow access speed. The general method takes 50 seconds, and multi-threading takes 10 seconds.
Interpretation of multi-threaded code:
# 创建线程类，继承Thread类 class MyThread(threading.Thread): def __init__(self, func, args): threading.Thread.__init__(self) # 调用父类的构造函数 self.args = args self.func = func def run(self): # 线程活动方法 apply(self.func, self.args)
threadList = [MyThread(open_url, (url,)) for url in urlList] # 调用线程类创建新线程，返回线程列表 for t in threadList: t.setDaemon(True) # 设置守护线程，父线程会等待子线程执行完后再退出 t.start() # 线程开启 for i in threadList: i.join() # 等待线程终止，等子线程执行完后再执行父线程
The above is the entire content of this article, I hope it will be helpful to everyone’s study.
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
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
PHP and Python: Different Paradigms Explained
Apr 18, 2025 am 12:26 AM
PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.
Choosing Between PHP and Python: A Guide
Apr 18, 2025 am 12:24 AM
PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.
Python vs. JavaScript: The Learning Curve and Ease of Use
Apr 16, 2025 am 12:12 AM
Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.
PHP and Python: A Deep Dive into Their History
Apr 18, 2025 am 12:25 AM
PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.
Can vs code run in Windows 8
Apr 15, 2025 pm 07:24 PM
VS Code can run on Windows 8, but the experience may not be great. First make sure the system has been updated to the latest patch, then download the VS Code installation package that matches the system architecture and install it as prompted. After installation, be aware that some extensions may be incompatible with Windows 8 and need to look for alternative extensions or use newer Windows systems in a virtual machine. Install the necessary extensions to check whether they work properly. Although VS Code is feasible on Windows 8, it is recommended to upgrade to a newer Windows system for a better development experience and security.
Can visual studio code be used in python
Apr 15, 2025 pm 08:18 PM
VS Code can be used to write Python and provides many features that make it an ideal tool for developing Python applications. It allows users to: install Python extensions to get functions such as code completion, syntax highlighting, and debugging. Use the debugger to track code step by step, find and fix errors. Integrate Git for version control. Use code formatting tools to maintain code consistency. Use the Linting tool to spot potential problems ahead of time.
Is the vscode extension malicious?
Apr 15, 2025 pm 07:57 PM
VS Code extensions pose malicious risks, such as hiding malicious code, exploiting vulnerabilities, and masturbating as legitimate extensions. Methods to identify malicious extensions include: checking publishers, reading comments, checking code, and installing with caution. Security measures also include: security awareness, good habits, regular updates and antivirus software.
How to run python with notepad
Apr 16, 2025 pm 07:33 PM
Running Python code in Notepad requires the Python executable and NppExec plug-in to be installed. After installing Python and adding PATH to it, configure the command "python" and the parameter "{CURRENT_DIRECTORY}{FILE_NAME}" in the NppExec plug-in to run Python code in Notepad through the shortcut key "F6".
