liunx 下线程优先级反转 的C语言使用示例

在Linux系统下，调整线程优先级通常使用`sched_setscheduler()`函数，而C语言标准库中的`pthread`库提供了相应的接口来操作线程调度。线程优先级反转是指原本高优先级的线程被切换到低优先级，而低优先级的线程获得更高的优先权。这里有一个简单的示例：

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>

// 定义线程优先级枚举值
enum thread_priority {
    LOW_PRIORITY = SCHED_YIELD,
    HIGH_PRIORITY = SCHED_RR
};

// 高优先级任务函数
void high_priority_task(void* arg) {
    pthread_attr_t attr;
    pthread_attr_init(&attr);
    
    // 设置高优先级
    pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
    pthread_attr_setschedparam(&attr, THREAD_PRIORITY_POLICY, HIGH_PRIORITY);

    while (true) {
        printf("High priority task running\n");
        sleep(1); // 模拟耗时任务
    }
}

// 低优先级任务函数
void low_priority_task(void* arg) {
    pthread_attr_t attr;
    pthread_attr_init(&attr);
    
    // 设置低优先级
    pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
    pthread_attr_setschedparam(&attr, THREAD_PRIORITY_POLICY, LOW_PRIORITY);

    while (true) {
        printf("Low priority task running\n");
        sched_yield(); // 切换当前进程让出CPU
        sleep(1);
    }
}

int main() {
    pthread_t high_thread, low_thread;

    // 创建并启动高优先级线程
    if (pthread_create(&high_thread, NULL, high_priority_task, NULL)) {
        perror("Failed to create high priority thread");
        exit(EXIT_FAILURE);
    }

    // 创建并启动低优先级线程
    if (pthread_create(&low_thread, NULL, low_priority_task, NULL)) {
        perror("Failed to create low priority thread");
        exit(EXIT_FAILURE);
    }

    // 等待两个线程结束
    pthread_join(high_thread, NULL);
    pthread_join(low_thread, NULL);

    return 0;
}