Java Thread Synchronization and Mutual Exclusion: Revealing the Secrets of Concurrent Programming

Java thread synchronization and mutual exclusion have always been important topics in concurrent programming. In a multi-threaded environment, ensuring thread safety is crucial. This article will delve into the concepts of thread synchronization and mutual exclusion in Java and reveal the secrets of concurrent programming. Let’s take a look at these key concepts to learn how to effectively manage threads and avoid issues like race conditions. PHP editor Youzi will lead you to gradually unlock the mysteries of these concurrent programming, allowing you to have a deeper understanding of the thread synchronization and mutual exclusion mechanisms in Java.

ThreadsSynchronization means that when multiple threads access shared resources, they coordinate their access sequence and behavior through some mechanism to prevent data confusion and program crashes.

2. Synchronization mechanism:

Java provides a variety of synchronization mechanisms, including locks, synchronization methods, synchronized blocks, atomic variables, etc. The purpose of these mechanisms is to ensure that shared resources can only be accessed by one thread at a time.

3. Lock:

Lock is a common synchronization mechanism that allows one thread to have exclusive access to shared resources. When a thread acquires a lock, other threads must wait until the thread releases the lock before continuing execution.

4. Synchronized methods and synchronized blocks:

Synchronized methods and synchronized blocks are implemented by adding the synchronized keyword before the method or code block. When a thread enters a synchronized method or synchronized block, it automatically acquires the lock, and other threads must wait until the thread releases the lock to continue execution.

5. Atomic variables:

Atomic variables are a special type of variables that can be guaranteed to be updated correctly in a multi-threaded environment. Atomic variables provide a variety of operation methods, such as compareAndSet() and getAndIncrement(), which ensure that updates to atomic variables are atomic.

2. Thread mutual exclusion:

1. Thread mutual exclusion concept:

Thread mutual exclusion means that when multiple threads access shared resources at the same time, their access to shared resources is restricted through some mechanism to prevent conflicts and data confusion.

2. Mutual exclusion mechanism:

Java provides a variety of mutual exclusion mechanisms, including locks, semaphores, barriers, etc. The purpose of these mechanisms is to ensure that shared resources can only be accessed by one thread at the same time.

3. Lock:

Lock is a common mutual exclusion mechanism that allows one thread to have exclusive access to shared resources. When a thread acquires a lock, other threads must wait until the thread releases the lock before continuing execution.

4. Semaphore:

A semaphore is a special variable that can limit the number of accesses to shared resources. When a thread obtains the semaphore, it can access the shared resource. When another thread attempts to access a shared resource, if the semaphore is already full, the thread must wait until the semaphore is released before continuing execution.

5. Barrier:

The barrier is a special synchronization mechanism that ensures that no thread can continue execution until all threads reach a certain point. Barriers can be used to coordinate operations between threads, such as waiting for all threads to complete their tasks before continuing with subsequent steps.

3. Demo code:

public class ThreadSyncDemo {
private static int count = 0;

public static void main(String[] args) {
// 创建两个线程
Thread thread1 = new Thread(() -> {
for (int i = 0; i < 10000; i++) {
// 同步方法
incrementCount();
}
});
Thread thread2 = new Thread(() -> {
for (int i = 0; i < 10000; i++) {
// 同步方法
incrementCount();
}
});

// 启动线程
thread1.start();
thread2.start();

// 等待线程结束
try {
thread1.join();
thread2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}

// 打印最终结果
System.out.println("Final count: " + count);
}

// 同步方法
private static synchronized void incrementCount() {
count++;
}
}

4. Summary:

Thread synchronization and mutual exclusion are very important concepts in Concurrent programming. They can ensure the correctness and consistency of shared resources. Java provides a variety of synchronization and mutual exclusion mechanisms, including locks, synchronized methods, synchronized blocks, atomic variables, semaphores, barriers, etc. By using these mechanisms appropriately, efficient and robust concurrency programs can be written.

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