jeurope_12_09_2024

package com.pivovarit.demo;

import com.pivovarit.collectors.ParallelCollectors;

import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * @author Grzegorz Piwowarek
 * @twitter @pivovarit
 * @github pivovarit
 */
class VirtualThreadsInAction {

    public static void main(String[] args) {
        try (ExecutorService ex = Executors.newVirtualThreadPerTaskExecutor()) {
            List<Integer> result = timed(() -> Stream.iterate(0, i -> i + 1)
              .limit(1000)
              .collect(ParallelCollectors.parallel(i -> process(i), Collectors.toList(), ex))
              .join());
        }
    }

    private static <T> T timed(Supplier<T> action) {
        long before = System.currentTimeMillis();
        T result = action.get();
        long after = System.currentTimeMillis();
        System.out.println("took " + (after - before) + "ms");
        return result;
    }

    private static <T> T process(T input) {
        System.out.println("processing " + input + " on " + Thread.currentThread().getName());
        try {
            synchronized (new Object()) {
                Thread.sleep(2000);
            }
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        return input;
    }

    public static void perfTest(String[] args) throws InterruptedException {
        ExecutorService ex = Executors.newVirtualThreadPerTaskExecutor();
        for (int i = 0; i < 5000; i++) {
            CompletableFuture.runAsync(() -> {
                try {
                    var before = System.currentTimeMillis();
                    String result = HttpClient.newHttpClient()
                      .send(HttpRequest.newBuilder()
                        .GET()
                        .uri(URI.create("http://localhost:8080/api/uuid"))
                        .build(), HttpResponse.BodyHandlers.ofString())
                      .body();

                    var after = System.currentTimeMillis();

                    System.out.printf("result = %s in %dms%n", result, after - before);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }, ex);
        }
        Thread.sleep(100000);
    }
}