executorservice

import java.util.Arrays; import java.util.Iterator; import java.util.List; import java.util.concurrent.Callable; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Future; import java.util.concurrent.TimeUnit; class Task implements Callable<String> { public String call() throws Exception { String s = "initial"; try { System.out.println("Started.."); /*for (int i=0;i<10000;i++) { if (i % 2 == 0) { System.out.println("Even"); } }*/ boolean flag = true; while(flag) { } System.out.println("Finished!"); s = "Done"; } catch

I am posed with the following problem: I need to split work across multiple threads for perfomance reasons, but I am not sure what approach to take. Firstly, the task I would be supplying should return a value and take a parameter. Additionally, the main method (doing the main bit of work, not static main() ) is already running on separate thread and is invoked periodically. Also, this method must at some point WAIT for all threads to finish and then proceed. One approach (most obvious to me) is to schedule each job on a separate thread and store results in class vars: public Object result1,

This question already has an answer here: How to wait for all threads to finish, using ExecutorService? 24 answers I need to submit a number of task and then wait for them until all results are available. Each of them adds a String to a Vector (that is synchronized by default). Then I need to start a new task for each result in the Vector but I need to do this only when all the previous tasks have stopped doing their job. I want to use Java Executor, in particular I tried using Executors.newFixedThreadPool(100) in order to use a fixed number of thread (I have a variable number of task that can

I submitted bunch of jobs to an executorservice in Java and I somehow want to temporarily pause all these jobs. What's the best way to do this? How can I resume? Or am I doing this completely wrong? Should I follow some other pattern for what I want to achieve (i.e. ability to pause/resume execution services)? To answer my own question, I found an example of a PausableThreadPoolExecutor in the javadocs of ThreadPoolExecutor itself . Here is my version using Guava's Monitors: import com.google.common.util.concurrent.Monitor; import java.util.concurrent.ScheduledThreadPoolExecutor; import java

Since use ExecutorService can submit a Callable task and return a Future , why need to use FutureTask to wrap Callable task and use the method execute ? I feel they both do the same thing. In fact you are correct. The two approaches are identical. You generally don't need to wrap them yourself. If you are, you're likely duplicating the code in AbstractExecutorService: /** * Returns a <tt>RunnableFuture</tt> for the given callable task. * * @param callable the callable task being wrapped * @return a <tt>RunnableFuture</tt> which when run will call the * underlying callable and which, as a <tt

I am working on a multithreaded project in which I need to spawn multiple threads to measure the end to end performance of my client code, as I'm doing Load and Performance testing. So I created the below code which is using ExecutorService . Below is the code with ExecutorService : public class MultithreadingExample { public static void main(String[] args) throws InterruptedException { ExecutorService executor = Executors.newFixedThreadPool(20); for (int i = 0; i < 100; i++) { executor.submit(new NewTask()); } executor.shutdown(); executor.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS); } }

What is the difference between ExecutorService eService = Executors.newFixedThreadPool(2); eService.execute(new TestThread6()); eService.execute(new TestThread6()); eService.execute(new TestThread6()); eService.awaitTermination(1, TimeUnit.NANOSECONDS); eService.shutdown(); and eService.shutdown(); eService.awaitTermination(1, TimeUnit.NANOSECONDS); I don't really understand shutdown() . This method does not wait for previously submitted tasks to complete execution. Does it mean shutdown() may terminate the tasks which have been submitted, but not completed? I tried some examples, they do not