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.
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Python and C each have their own advantages, and the choice should be based on project requirements. 1) Python is suitable for rapid development and data processing due to its concise syntax and dynamic typing. 2)C is suitable for high performance and system programming due to its static typing and manual memory management.

Choosing Python or C depends on project requirements: 1) If you need rapid development, data processing and prototype design, choose Python; 2) If you need high performance, low latency and close hardware control, choose C.

By investing 2 hours of Python learning every day, you can effectively improve your programming skills. 1. Learn new knowledge: read documents or watch tutorials. 2. Practice: Write code and complete exercises. 3. Review: Consolidate the content you have learned. 4. Project practice: Apply what you have learned in actual projects. Such a structured learning plan can help you systematically master Python and achieve career goals.

Methods to learn Python efficiently within two hours include: 1. Review the basic knowledge and ensure that you are familiar with Python installation and basic syntax; 2. Understand the core concepts of Python, such as variables, lists, functions, etc.; 3. Master basic and advanced usage by using examples; 4. Learn common errors and debugging techniques; 5. Apply performance optimization and best practices, such as using list comprehensions and following the PEP8 style guide.

Python is suitable for beginners and data science, and C is suitable for system programming and game development. 1. Python is simple and easy to use, suitable for data science and web development. 2.C provides high performance and control, suitable for game development and system programming. The choice should be based on project needs and personal interests.

Python is more suitable for data science and rapid development, while C is more suitable for high performance and system programming. 1. Python syntax is concise and easy to learn, suitable for data processing and scientific computing. 2.C has complex syntax but excellent performance and is often used in game development and system programming.

It is feasible to invest two hours a day to learn Python. 1. Learn new knowledge: Learn new concepts in one hour, such as lists and dictionaries. 2. Practice and exercises: Use one hour to perform programming exercises, such as writing small programs. Through reasonable planning and perseverance, you can master the core concepts of Python in a short time.

Python is easier to learn and use, while C is more powerful but complex. 1. Python syntax is concise and suitable for beginners. Dynamic typing and automatic memory management make it easy to use, but may cause runtime errors. 2.C provides low-level control and advanced features, suitable for high-performance applications, but has a high learning threshold and requires manual memory and type safety management.


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