One virtual thread per task

Definition

The usual way to use virtual threads is an executor that starts a new virtual thread for every task. Because they are cheap you do not pool them. Using the executor in try-with-resources waits for all tasks before continuing.

Example code

Fetching 5 values at the same time with plain blocking code

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

class Demo {
    static String fetch(int id) throws InterruptedException {
        Thread.sleep(200);                                  // blocking is cheap on a virtual thread
        return "item-" + id;
    }

    public static void main(String[] args) throws Exception {
        List<Future<String>> futures = new ArrayList<>();

        try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
            for (int id = 1; id <= 5; id++) {
                int copy = id;
                futures.add(executor.submit(() -> fetch(copy)));
            }
        }                                                    // waits here until all 5 are done

        for (Future<String> future : futures) System.out.println(future.get());
    }
}

// Output:
// item-1
// item-2
// item-3
// item-4
// item-5