Executors newCachedThreadPool Method Example

In this article, we will learn about the Executor’s newCachedThreadPool factory method.

Executors.newCachedThreadPool() Method

This method creates a thread pool that creates new threads as needed but will reuse previously constructed threads when they are available. These pools will typically improve the performance of programs that execute many short-lived asynchronous tasks.
Calls to execute will reuse previously constructed threads if available. If no existing thread is available, a new thread will be created and added to the pool. Threads that have not been used for sixty seconds are terminated and removed from the cache. Thus, a pool that remains idle for long enough will not consume any resources. Note that pools with similar properties but different details (for example, timeout parameters) may be created using ThreadPoolExecutor constructors.
Syntax:
final ExecutorService executorService = Executors.newCachedThreadPool();

Executors.newCachedThreadPool() Method Example

import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class CachedThreadPoolExample {

    public static void main(final String[] args) throws InterruptedException, ExecutionException {

        System.out.println("Thread main started");

        Runnable task1 = () -> {
             System.out.println("Executing Task1 inside : " + Thread.currentThread().getName());
             try {
                  TimeUnit.SECONDS.sleep(2);
             } catch (InterruptedException ex) {
                  throw new IllegalStateException(ex);
             }
        };

        Runnable task2 = () -> {
             System.out.println("Executing Task2 inside : " + Thread.currentThread().getName());
             try {
                  TimeUnit.SECONDS.sleep(4);
             } catch (InterruptedException ex) {
                  throw new IllegalStateException(ex);
             }
       };

        Runnable task3 = () -> {
            System.out.println("Executing Task3 inside : " + Thread.currentThread().getName());
            try {
                 TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException ex) {
                 throw new IllegalStateException(ex);
            }
        };

        final ExecutorService executorService = Executors.newCachedThreadPool();
        System.out.println("Submitting the tasks for execution...");
        executorService.submit(task1);
        executorService.submit(task2);
        executorService.submit(task3);

        executorService.shutdown();

        System.out.println("Thread main finished");
    }
}
Output:
Thread main started
Submitting the tasks for execution...
Executing Task1 inside : pool-1-thread-1
Executing Task3 inside : pool-1-thread-3
Executing Task2 inside : pool-1-thread-2
Thread main finished


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