CountdownLatch 演示程序。不等待 countdownlatch 结束
CountdownLatch Demo program .Not waiting for coutdown latch to get over
在这个程序中,为什么 All countdownlatch over message 打印在两者之间。尽管它应该等待所有倒计时锁存器结束。因为在 main 方法中启动了一个额外的线程,但应该将其处理为 cdl.countDown() 方法被调用来处理此线程的倒计时。
为什么它违反了倒计时闩锁?
import java.util.concurrent.CountDownLatch;
public class CDLDemo implements Runnable {
static int count = 0;
CountDownLatch cdl = new CountDownLatch(5);
void checkForAwait() {
cdl.countDown();
System.out.println("Start " + cdl.getCount());
CDLTask1 cdlTask1 = new CDLTask1(cdl);
CDLTask2 cdlTask2 = new CDLTask2(cdl);
CDLTask3 cdlTask3 = new CDLTask3(cdl);
CDLTask4 cdlTask4 = new CDLTask4(cdl);
Thread t1 = new Thread(cdlTask1);
Thread t2 = new Thread(cdlTask2);
Thread t3 = new Thread(cdlTask3);
Thread t4 = new Thread(cdlTask4);
t1.start();
t2.start();
t3.start();
t4.start();
try {
cdl.await();
System.out.println("All countdownlatch over");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
@Override
public void run() {
checkForAwait();
}
public static void main(String[] args) throws InterruptedException {
CDLDemo cdlDemo = new CDLDemo();
Thread t1 = new Thread(cdlDemo, "Thread1");
t1.start();
t1.join();
System.out.println("All completed");
}
static int getCount() {
return count++;
}
static class CDLTask1 implements Runnable {
CountDownLatch cdl;
public CDLTask1(CountDownLatch cdl) {
this.cdl = cdl;
}
@Override
public void run() {
getCount();
cdl.countDown();
System.out.println("Available count :" + cdl.getCount() + "" + Thread.currentThread().getName());
}
}
static class CDLTask2 implements Runnable {
CountDownLatch cdl;
public CDLTask2(CountDownLatch cdl) {
this.cdl = cdl;
}
@Override
public void run() {
cdl.countDown();
System.out.println("Available count :" + cdl.getCount() + "" + Thread.currentThread().getName());
}
}
static class CDLTask3 implements Runnable {
CountDownLatch cdl;
public CDLTask3(CountDownLatch cdl) {
this.cdl = cdl;
}
@Override
public void run() {
cdl.countDown();
System.out.println("Available count :" + cdl.getCount() + "" + Thread.currentThread().getName());
}
}
static class CDLTask4 implements Runnable {
CountDownLatch cdl;
public CDLTask4(CountDownLatch cdl) {
this.cdl = cdl;
}
@Override
public void run() {
cdl.countDown();
System.out.println("Available count :" + cdl.getCount() + "" + Thread.currentThread().getName());
}
}
}
您在 CDLTask 中的打印语句在 cdl.countDown()
之后,这就是为什么您在两者之间收到消息的原因。该线程可能会在倒计时和打印语句之间被抢占,然后您的主线程可能会在所有打印完成之前发出信号。
在这个程序中,为什么 All countdownlatch over message 打印在两者之间。尽管它应该等待所有倒计时锁存器结束。因为在 main 方法中启动了一个额外的线程,但应该将其处理为 cdl.countDown() 方法被调用来处理此线程的倒计时。 为什么它违反了倒计时闩锁?
import java.util.concurrent.CountDownLatch;
public class CDLDemo implements Runnable {
static int count = 0;
CountDownLatch cdl = new CountDownLatch(5);
void checkForAwait() {
cdl.countDown();
System.out.println("Start " + cdl.getCount());
CDLTask1 cdlTask1 = new CDLTask1(cdl);
CDLTask2 cdlTask2 = new CDLTask2(cdl);
CDLTask3 cdlTask3 = new CDLTask3(cdl);
CDLTask4 cdlTask4 = new CDLTask4(cdl);
Thread t1 = new Thread(cdlTask1);
Thread t2 = new Thread(cdlTask2);
Thread t3 = new Thread(cdlTask3);
Thread t4 = new Thread(cdlTask4);
t1.start();
t2.start();
t3.start();
t4.start();
try {
cdl.await();
System.out.println("All countdownlatch over");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
@Override
public void run() {
checkForAwait();
}
public static void main(String[] args) throws InterruptedException {
CDLDemo cdlDemo = new CDLDemo();
Thread t1 = new Thread(cdlDemo, "Thread1");
t1.start();
t1.join();
System.out.println("All completed");
}
static int getCount() {
return count++;
}
static class CDLTask1 implements Runnable {
CountDownLatch cdl;
public CDLTask1(CountDownLatch cdl) {
this.cdl = cdl;
}
@Override
public void run() {
getCount();
cdl.countDown();
System.out.println("Available count :" + cdl.getCount() + "" + Thread.currentThread().getName());
}
}
static class CDLTask2 implements Runnable {
CountDownLatch cdl;
public CDLTask2(CountDownLatch cdl) {
this.cdl = cdl;
}
@Override
public void run() {
cdl.countDown();
System.out.println("Available count :" + cdl.getCount() + "" + Thread.currentThread().getName());
}
}
static class CDLTask3 implements Runnable {
CountDownLatch cdl;
public CDLTask3(CountDownLatch cdl) {
this.cdl = cdl;
}
@Override
public void run() {
cdl.countDown();
System.out.println("Available count :" + cdl.getCount() + "" + Thread.currentThread().getName());
}
}
static class CDLTask4 implements Runnable {
CountDownLatch cdl;
public CDLTask4(CountDownLatch cdl) {
this.cdl = cdl;
}
@Override
public void run() {
cdl.countDown();
System.out.println("Available count :" + cdl.getCount() + "" + Thread.currentThread().getName());
}
}
}
您在 CDLTask 中的打印语句在 cdl.countDown()
之后,这就是为什么您在两者之间收到消息的原因。该线程可能会在倒计时和打印语句之间被抢占,然后您的主线程可能会在所有打印完成之前发出信号。