How to Fix: Java Multithreading Error: Thread Scheduling Issues

How to solve: Java multi-threading error: thread scheduling problem

Introduction:
When using Java for multi-threaded programming, we often encounter some threads Scheduling issues. Due to the simultaneous execution of multiple threads, the execution order and execution time between threads are uncertain, which may lead to some unexpected errors. This article will introduce some common thread scheduling problems and provide solutions and sample code.

1. Common manifestations of thread scheduling problems:

1. Threads cannot be executed in the expected order;
2. The order of thread execution is unstable;
3. Too long thread execution time causes performance problems;
4. Thread execution results are inconsistent.

2. Solution:

1. Use thread synchronization mechanism: control the execution order and mutual exclusion of multiple threads by using the synchronized keyword, lock object or concurrent container Access shared resources.
2. Use thread scheduling tools: Control the execution order and time of threads by using thread priority, sleep, wait, and wake-up methods.

3. Sample code:

1. Use the synchronized keyword to achieve thread synchronization

public class ThreadDemo {
    public static void main(String[] args) {
        Printer printer = new Printer();

        Thread thread1 = new Thread(printer);
        Thread thread2 = new Thread(printer);

        thread1.start();
        thread2.start();
    }
}

class Printer implements Runnable {
    @Override
    public void run() {
        synchronized (this) {
            for (int i = 0; i < 5; i++) {
                System.out.println(Thread.currentThread().getName() + ": " + i);
            }
        }
    }
}

2. Use Lock lock to achieve thread synchronization

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ThreadDemo {
    public static void main(String[] args) {
        Printer printer = new Printer();

        Thread thread1 = new Thread(printer);
        Thread thread2 = new Thread(printer);

        thread1.start();
        thread2.start();
    }
}

class Printer implements Runnable {
    private Lock lock = new ReentrantLock();

    @Override
    public void run() {
        lock.lock();
        try {
            for (int i = 0; i < 5; i++) {
                System.out.println(Thread.currentThread().getName() + ": " + i);
            }
        } finally {
            lock.unlock();
        }
    }
}

3. Use thread scheduling tools to achieve thread control

public class ThreadDemo {
    public static void main(String[] args) {
        Thread thread1 = new Thread(new Printer(), "Thread 1");
        Thread thread2 = new Thread(new Printer(), "Thread 2");

        thread1.setPriority(Thread.MIN_PRIORITY);  // Thread.MIN_PRIORITY = 1
        thread2.setPriority(Thread.MAX_PRIORITY);  // Thread.MAX_PRIORITY = 10

        thread1.start();
        thread2.start();
    }
}

class Printer implements Runnable {
    @Override
    public void run() {
        for (int i = 0; i < 5; i++) {
            System.out.println(Thread.currentThread().getName() + ": " + i);
            try {
                Thread.sleep(100);  // 模拟耗时操作
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

4. Conclusion:
In multi-thread programming, thread scheduling problems are a common type mistake. By using thread synchronization mechanisms and thread scheduling tools, we can solve thread scheduling problems, ensure that the order and time of threads are controlled, and obtain correct execution results. I hope the solutions and sample code introduced in this article will be helpful for you to understand and solve the Java multi-threading error: thread scheduling problem.

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