Java SynchronousQueue-白红宇

Java SynchronousQueue

阅读量：6705 次

发布时间：2019-06-25

本文共 3633 字，大约阅读时间需要 12 分钟。

This Java tutorial is to learn about the concurrent collection SynchronousQueue. It is an implementation of BlockingQueue. Among all Java concurrent collections, SynchronousQueue is different. Capacity of a synchrounous queue is always zero. It is because in SynchronousQueue an insert will wait for a remove operation by another thread and vice versa.

put() call to a SynchronousQueue will not return until there is a corresponding take() call.

peek is not possible with a SynchronousQueue

As there is no element iteration is also not possible.

Insert is not possible if there is a thread trying to remove it.

SynchronousQueue should be imagined like a baton in a relay race.

If there are more than one thread waiting for a removal so that they can do insert then with fairness set to true, threads are granted access in FIFO order.

SynchronousQueue is the default BlockingQueue used for the Executors.newCachedThreadPool() methods.

SynchronousQueue Example

Let us have a look at a producer-consumer based example to understand the SynchronousQueue.

SynchronousQueueProducer.java

package com.javapapers.java.collections;import java.util.Random;import java.util.UUID;import java.util.concurrent.BlockingQueue;public class SynchronousQueueProducer implements Runnable {	protected BlockingQueue
     
       blockingQueue;	final Random random = new Random();	public SynchronousQueueProducer(BlockingQueue
      
        queue) {		this.blockingQueue = queue;	}	@Override	public void run() {		while (true) {			try {				String data = UUID.randomUUID().toString();				System.out.println("Put: " + data);				blockingQueue.put(data);				Thread.sleep(1000);			} catch (InterruptedException e) {				e.printStackTrace();			}		}	}}

SynchronousQueueConsumer.java

package com.javapapers.java.collections;import java.util.concurrent.BlockingQueue;public class SynchronousQueueConsumer implements Runnable {	protected BlockingQueue
     
       blockingQueue;	public SynchronousQueueConsumer(BlockingQueue
      
        queue) {		this.blockingQueue = queue;	}	@Override	public void run() {		while (true) {			try {				String data = blockingQueue.take();				System.out.println(Thread.currentThread().getName()						+ " take(): " + data);				Thread.sleep(2000);			} catch (InterruptedException e) {				e.printStackTrace();			}		}	}}

SynchronousQueueExample.java

package com.javapapers.java.collections;import java.util.concurrent.BlockingQueue;import java.util.concurrent.SynchronousQueue;public class SynchronousQueueExample {	public static void main(String[] args) {		final BlockingQueue
     
       synchronousQueue = new SynchronousQueue
      
       ();		SynchronousQueueProducer queueProducer = new SynchronousQueueProducer(				synchronousQueue);		new Thread(queueProducer).start();		SynchronousQueueConsumer queueConsumer1 = new SynchronousQueueConsumer(				synchronousQueue);		new Thread(queueConsumer1).start();		SynchronousQueueConsumer queueConsumer2 = new SynchronousQueueConsumer(				synchronousQueue);		new Thread(queueConsumer2).start();	}}

Example Output

Put: 4c34138b-51dd-4c2c-9633-87a147253978Thread-2 take(): 4c34138b-51dd-4c2c-9633-87a147253978Put: 39682e81-9ba8-4b29-a37e-3dc4d5cdb1f7Thread-1 take(): 39682e81-9ba8-4b29-a37e-3dc4d5cdb1f7Put: e21dbfd2-d007-43d2-9733-cb10ce683d81Thread-2 take(): e21dbfd2-d007-43d2-9733-cb10ce683d81Put: 556c5584-7154-4117-a0f4-f52ec8dcfad8Thread-1 take(): 556c5584-7154-4117-a0f4-f52ec8dcfad8Put: 1da7f16c-c030-44ed-be02-8983b7387497Thread-2 take(): 1da7f16c-c030-44ed-be02-8983b7387497

原文连接：

翻译：

转载于:https://www.cnblogs.com/chenjunjie12321/p/9516068.html

你可能感兴趣的文章