Created
November 21, 2019 00:16
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CompletableFutures newWorkStealingPool test
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| import org.junit.Test; | |
| import java.util.ArrayList; | |
| import java.util.List; | |
| import java.util.concurrent.CompletableFuture; | |
| import java.util.concurrent.ExecutorService; | |
| import java.util.concurrent.Executors; | |
| import java.util.concurrent.TimeUnit; | |
| import org.slf4j.Logger; | |
| import org.slf4j.LoggerFactory; | |
| public class G1Test { | |
| Logger logger = LoggerFactory.getLogger(G1Test.class); | |
| // ExecutorService e1 = Executors.newFixedThreadPool(2); | |
| ExecutorService e1 = Executors.newWorkStealingPool(2); | |
| @Test | |
| public void test() { | |
| // Gather CompletableFutures to wait for them at the end | |
| List<CompletableFuture> futures = new ArrayList<>(); | |
| // First steps | |
| for (int i = 0; i < 5; i++) { | |
| int finalI = i; | |
| CompletableFuture<Void> fut = CompletableFuture.supplyAsync(() -> { | |
| logger.info("Start step a - " + finalI); | |
| //simulateLongProcessing();// just waits for 1 s | |
| try { | |
| Thread.sleep(1000); | |
| } catch (InterruptedException e) { | |
| e.printStackTrace(); | |
| } | |
| logger.info("End step a - " + finalI); | |
| return "step1 output - " + finalI; | |
| }, e1) | |
| .orTimeout(5000, TimeUnit.MILLISECONDS) | |
| .exceptionally(t -> "exp 1 output " + finalI) | |
| .thenComposeAsync(s -> { | |
| List<CompletableFuture> subFutures = new ArrayList<>(); | |
| // Second step : Launch several sub-tasks based on the result of the first step | |
| for (int j = 0; j < 5; j++) { | |
| final int finalJ = j; | |
| CompletableFuture<String> f = CompletableFuture.supplyAsync(() -> { | |
| logger.info("Start - step b : " + s + " | " + finalJ); | |
| //simulateLongProcessing(); | |
| logger.info("End - step b : " + s + " | " + finalJ); | |
| return "step2 output - " + s + " | " + finalJ; | |
| }, e1); | |
| subFutures.add(f); | |
| } | |
| return CompletableFuture.allOf(subFutures.toArray(new CompletableFuture[0])); | |
| }, e1); | |
| futures.add(fut); | |
| } | |
| // Wait for the completion | |
| for (CompletableFuture future : futures) { | |
| future.join(); | |
| } | |
| } | |
| } |
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