Multi-thread countdown timer countdownlatch and loop fence Cyclicbarrier

1. Countdown Timer Countdownlatch
Countdownlatch is a multi-line program-based tool class. Typically used to control thread waits, it allows a thread to wait until the timing is over before it starts executing.
constructor function:
public Countdownlatch (int count)//count count

例如：在主线程中启动10个子线程去数据库中获取分页数据，需要等到所有线程数据都返回之后统一做统计处理

public class Countdownlatchdemo implements runnable{
private static final Countdownlatch end = new Countdownlatch (10);
@Override
public void Run () {
SYSTEM.OUT.PRINTLN ("Thread Name:" + Thread.CurrentThread (). GetName ());
Data Service Processing
End.countdown ();//Count minus 1
}

public static void main(String[] args) {    CountDownLatchDemo countDownLatchDemo = new CountDownLatchDemo();    System.out.println("计数开始");    for (int i = 0; i < 10; i++) {        new Thread(countDownLatchDemo).start();    }    try {        end.await();        System.out.println("计数结束");    } catch (InterruptedException e) {        e.printStackTrace();    }}

}

上述代码使用CountDownLatch的await()方法，要求主线程等待所有10个计数任务全部完成后，主线程才开始继续执行可以通过getCount()方法获取当前的计数个数，当计数结束时count为0，且不会被重置

2. Circular Fence Cyclicbarrier
Cyclicbarrier is also a tool for multithreading concurrency control. More powerful than Countdownlatch,cyclicbarrier features, mainly in:
1) Construction Method:
public Cyclicbarrier (int parties, Runnable barrieraction)
Cyclicbarrier's construction method can be passed to a runnable barrieraction, which can be used to do a specific thing after the thread is assembled.
2) Cyclicbarrier can be reused, when a batch of thread parties is, the counter will be zeroed, restart counting

public class Cyclicbarrierdemo {

Class Soldier implements runnable{private Cyclicbarrier cyclicbarrier;    Public Soldier (Cyclicbarrier cyclicbarrier) {this.cyclicbarrier = Cyclicbarrier;        } @Override public void Run () {System.out.println ("soldier" + Thread.CurrentThread (). GetId () + "report");            try {//wait for all soldiers to go to Qi cyclicbarrier.await ();            Perform task doWork ();        Cyclicbarrier.await ();        } catch (Interruptedexception e) {e.printstacktrace ();        } catch (Brokenbarrierexception e) {e.printstacktrace ();        }} private void DoWork () throws Interruptedexception {thread.sleep (1000);    System.out.println ("Soldier" + Thread.CurrentThread (). GetId () + "task Complete");    }}class Commond implements runnable{@Override public void Run () {System.out.println ("End of Task");    }}public static void Main (string[] args) {Cyclicbarrierdemo Cyclicbarrierdemo = new Cyclicbarrierdemo (); Cyclicbarrier Cyclicbarrier = New Cyclicbarrier (5, Cyclicbarrierdemo.new Commond ());    for (int i = 0; i <; i++) {New Thread (cyclicbarrierdemo.new Soldier (Cyclicbarrier)). Start (); }}

}

Execution Result:

As you can see, the thread is divided into 5 groups of

Multi-thread countdown timer countdownlatch and loop fence Cyclicbarrier