Java 8 - Producer/Consumer threads using executor framework

Creating a thread consumes a significant amount of memory. In an application where there are lot of client programs, creating a thread per client will not scale. So, Java 5 came up with an executor framework to provide a thread pool for execution limiting the number of threads serving client request at any point of time. This helps in performance and in reducing the memory requirement.

Java 5 also provides blocking queue implementations and we no longer requires to control producer/consumer applications using wait/notify. This is automatically taken care by BlockingQueue implementations.

An example producer/consumer making use of a blocking queue implementation and executor framework is as follows:

package com.prasune.coding.thread; import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.BlockingQueue; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.logging.Level; import java.util.logging.Logger; public class TestProducerConsumer {     private static final int NUM_OF_MSGS = 20;     private static final BlockingQueue<String> queue                                                = new ArrayBlockingQueue<String>(5);     private static ExecutorService producerPool = Executors.newFixedThreadPool(3);     private static ExecutorService consumerPool = Executors.newFixedThreadPool(1);     private static Logger logger =                                                                               Logger.getLogger(TestProducerConsumer.class.getName());     public static void main(String[] args) {         Runnable producerTask = () -> {             try {                 queue.put("test Message");                 System.out.println(Thread.currentThread().getName()                                     + " put message queue.size() " + queue.size());             } catch (InterruptedException e) {                 logger.log(Level.SEVERE, e.getMessage(), e);             }         };         Runnable consumerTask = () -> {             try {                 System.out.println(Thread.currentThread().getName()                                     + " received msg " + queue.take());             } catch (InterruptedException e) {                 logger.log(Level.SEVERE, e.getMessage(), e);             }         };         try {             for (int i = 0; i < NUM_OF_MSGS; i++) {                 producerPool.submit(producerTask);             }             for (int i = 0; i < NUM_OF_MSGS; i++) {                 consumerPool.submit(consumerTask);             }         } finally {             if (producerPool != null) {                 producerPool.shutdown();             }             if (consumerPool != null) {                 consumerPool.shutdown();             }         }     } }