Zookeeper Study notes (vi) distributed barrier

When we need multiple threads to start at the same time, we can use the cyclibarrier that comes with the JDK. Let's take a look at its common uses:

Package com.my.CuratorTest;
Import java.util.concurrent.BrokenBarrierException;

Import Java.util.concurrent.CyclicBarrier; /** * Title: <br/> * Intention: <br/> * <p> * Class name:com.my.curatortest.cyclibarriertest<br/ > * Create date:2017/8/26 11:18 <br/> * Project name:mytest <br/> * company:all rights Reserved. <br/> * copyright©2017 <br/> * </p> * <p> * Author:gaowei <br/> * 1st_examiner: < br/> * 2nd_examiner: <br/> * </p> * * @version 1.0 * @since JDK 1.7 */public class Cyclibarriertest
		{public static void main (string[] args) {cyclicbarrier barrier = new Cyclicbarrier (5); for (int i = 0; i < 5; i++) {New Thread (new Runnable () {@Override public void run () {System.out.prin
					TLN (Thread.CurrentThread (). GetName () + ", waiting ...");
						try {barrier.await (); System.out.println (Thread.CurrentThread (). GetName () + "," + System.currenttimemillis() + ", start work");
					} catch (Interruptedexception e) {e.printstacktrace ();
					} catch (Brokenbarrierexception e) {e.printstacktrace ();
		}}). Start (); }
	}
}

Operation Result:

Thread-3, wait ...
Thread-1, wait ...
Thread-0, wait ...
Thread-2, wait ...
Thread-4, wait ...
Thread-4, 1503736464892, started working
Thread-3, 1503736464892, started working
Thread-0, 1503736464892, started working
Thread-1, 1503736464892, start work
Thread-2, 1503736464892, start working

So, in a distributed environment, how to solve the problem of multiple threads starting at the same time. Curator provides us with distributedbarrier (main thread triggering barrier release) and distributeddoublebarrier (thread spontaneous triggering barrier release).

Distributedbarrier is used as follows, copy the code on the book:

Package com.my.CuratorTest;
Import Org.apache.curator.framework.CuratorFramework;
Import Org.apache.curator.framework.CuratorFrameworkFactory;
Import Org.apache.curator.framework.recipes.barriers.DistributedBarrier;

Import Org.apache.curator.retry.ExponentialBackoffRetry; /** * Title: <br/> * Intention: <br/> * <p> * Class NAME:COM.MY.CURATORTEST.RECIPESBARRIER&LT;BR/&G
 T * Create DATE:2017/8/26 11:07 <br/> * Project name:mytest <br/> * company:all rights Reserved. <br/> * copyright©2017 <br/> * </p> * <p> * Author:gaowei <br/> * 1st_examiner: <

	br/> * 2nd_examiner: <br/> * </p> * * @version 1.0 * @since JDK 1.7 */public class Recipesbarrier {
	static String Barrierpath = "/curator_recipes_barrier_path";

	Static Distributedbarrier barrier; public static void Main (string[] args) throws Exception {for (int i=0;i<5;i++) {new Thread (new Runnable () {@ Override Public void Run () {curatorframework client = Curatorframeworkfactory.builder (). ConnectString ("127.0.0.1:2181")
					. Retrypolicy (New Exponentialbackoffretry (8)). Build ();
					Client.start ();
					Barrier = new Distributedbarrier (client, Barrierpath);
					System.out.println (Thread.CurrentThread (). GetName () + "number barrier settings");
						try {barrier.setbarrier ();
						Barrier.waitonbarrier ();
					System.err.println (Thread.CurrentThread (). GetName () + "start ...");
					} catch (Exception e) {e.printstacktrace ();
		}}). Start ();
		} thread.sleep (2000);
	Barrier.removebarrier (); }
}

Operation Result:

Thread-4 number Barrier set
Thread-2 number Barrier set Thread-3 number Barrier set Thread-0 number Barrier set Thread-1
number barrier
settings
Thread-3 start ...
Thread-4 start ...
Thread-2 start ...
Thread-0 start ...
Thread-1 start ...

The use of Distributeddoublebarrier is as follows:

Package com.my.CuratorTest;
Import Org.apache.curator.framework.CuratorFramework;
Import Org.apache.curator.framework.CuratorFrameworkFactory;
Import Org.apache.curator.framework.recipes.barriers.DistributedDoubleBarrier;

Import Org.apache.curator.retry.ExponentialBackoffRetry; /** * Title: <br/> * Intention: <br/> * <p> * Class name:com.my.curatortest.recipesbarrier2<br/&
 Gt * Create DATE:2017/8/26 16:05 <br/> * Project name:mytest <br/> * company:all rights Reserved. <br/> * copyright©2017 <br/> * </p> * <p> * Author:gaowei <br/> * 1st_examiner: < 

	br/> * 2nd_examiner: <br/> * </p> * * @version 1.0 * @since JDK 1.7 */public class RecipesBarrier2 {

	static String Barrierpath = "/curator_recipes_barrier_path";
				public static void Main (string[] args) {for (int i = 0; i < 5; i + +) {new Thread (new Runnable () {@Override public void Run () {try {CuratoRframework client = Curatorframeworkfactory.builder (). ConnectString ("127.0.0.1:2181"). Retrypolicy (New Ex
						Ponentialbackoffretry (3)). Build ();
						Client.start ();
						Distributeddoublebarrier barrier = new Distributeddoublebarrier (client, Barrierpath, 5);
						Thread.Sleep (Math.Round (Math.random () * 3000));
						System.out.println (Thread.CurrentThread (). GetName () + "sign into barrier");
						Barrier.enter ();
						System.out.println (Thread.CurrentThread (). GetName () + "start ...");
						Thread.Sleep (Math.Round (Math.random () * 3000));
						Barrier.leave ();
					System.out.println (Thread.CurrentThread (). GetName () + "Exit ...");
					} catch (Interruptedexception e) {e.printstacktrace ();
					} catch (Exception e) {e.printstacktrace ();
		}}). Start (); }
	}
}

Operation Result:

Thread-2 Enter barrier
Thread-1 Enter barrier Thread-4 enter
barrier Thread-0 Enter barrier Thread-3 enter barrier
Thread-3 start ...
Thread-4 start ...
Thread-1 start ...
Thread-0 start ...
Thread-2 start ...
Thread-2 exit ...
Thread-4 exit ...
Thread-0 exit ...
Thread-1 exit ...
Thread-3 exit ...