Java Threading and concurrency programming Practice----synchronizer (countdown latch)

The synchronized keyword provided by Java provides thread-synchronous access to critical sections. Because it is difficult to synchronized based

The synchronization code is written correctly, and the Concurrency tool class provides an advanced Synchronizer. Countdown latch (countdown latch), Sync screen

(cyclic barrier), switch (exchanger), Semaphore (semaphore), and Phaser Synchronizer. The following main

Introduce the countdown latch.

The countdown latch causes one or more threads to wait at the "door" until another thread opens the door, and the thread

Before it can continue to run. He consists of a count variable and two operations, each of which "causes a thread to wait until

The count changes to 0 "and" Decrement count variable ".

Implementation class: Java.util.concurrent.CountDownLatch

The following code, implemented with a countdown latch, is the execution of all threads at the same time and ends before the main thread can proceed:

import java.util.concurrent.countdownlatch;import java.util.concurrent.executorservice;import  Java.util.concurrent.executors;public class test {final static int nthreads  = 3;public static void main (String[] args)  {final countdownlatch  startsignal = new countdownlatch (1); final countdownlatch donesignal =  new countdownlatch (nthreads); Runnable r = new runnable ()  {@Overridepublic  void run ()  {try { System.out.println (Thread.CurrentThread (). GetName ()  +  "Enter Wait"); startsignal.await (); System.out.println (Thread.CurrentThread (). GetName ()  +  "Start performing tasks"); Thread.Sleep ($);d onesignal.countdown ();}  catch  (interruptedexception e)  {e.printstacktrace ();}}; Executorservice es = executors.newfixedthreadpool (nthreads);for  (int i = 0;  i < nthreads; i++)  {es.execute (r);} Try {thread.sleep (+); Startsignal.countdown (); System.out.println (Thread.CurrentThread (). GetName ()  +  "Enter Wait");d onesignal.await (); System.out.println (Thread.CurrentThread (). GetName ()  +  "Start Execution"); Es.shutdownnow ();}  catch  (interruptedexception e)  {e.printstacktrace ();}}

Java Threading and concurrency programming Practice----synchronizer (countdown latch)