Java 9 中 Thread.onSpinWait() 方法的重要性?
Thread.onSpinWait() 方法已在 Java 9 中引入。它是 Thread 类的静态方法,可以在忙等待循环中按需调用。在某些系统架构上,它允许 JVM 发出处理器指令以改善此类自旋等待循环的反应时间,同时降低核心线程的耗电量。它可以使 Java 程序的整体功耗受益,并允许其他核心线程在相同的功耗范围内以更快的速度执行。
语法
public static void onSpinWait()
示例
public class ThreadOnSpinWaitTest {
public static void main(final String args[]) throws InterruptedException {
final NormalTask task1 = new NormalTask();
final SpinWaitTask task2 = new SpinWaitTask();
final Thread thread1 = new Thread(task1);
thread1.start();
final Thread thread2 = new Thread(task2);
thread2.start();
new Thread(() -> {
try {
Thread.sleep(1000);
} catch(final InterruptedException e) {
e.printStackTrace();
} finally {
task1.start();
task2.sta*rt();
}
}).start();
thread1.join();
thread2.join();
}
private abstract static class Task implements Runnable {
volatile boolean canStart;
void start() {
this.canStart = true;
}
}
private static class NormalTask extends Task {
@Override
public void run() {
while(!this.canStart) {
}
System.out.println("Done!");
}
}
private static class SpinWaitTask extends Task {
@Override
public void run() {
while(!this.canStart) {
Thread.onSpinWait();
}
System.out.println("Done!");
}
}
}输出
Done! Done!
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