fix: reduce concurrent PWA icons generation tasks

mcollovati · mcollovati · commit 0df005b9039b · 2025-04-09T08:16:08.000+02:00
Submitting multiple asynchronous jobs to generate PWA icons at build time can cause OutOfMemory errors with Gradle. This change introduces a fixed thread pool executor so that fewer icon generations are processed concurrently, allowing the JVM to clean up memory for already generated images. Fixes #20842
diff --git a/flow-server/src/main/java/com/vaadin/flow/server/frontend/NodeTasks.java b/flow-server/src/main/java/com/vaadin/flow/server/frontend/NodeTasks.java
@@ -22,6 +22,7 @@
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -340,8 +341,14 @@ public void execute() throws ExecutionFailedException {
             sortCommands(commands);
             GeneratedFilesSupport generatedFilesSupport = new GeneratedFilesSupport();
             for (FallibleCommand command : commands) {
+                long startTime = System.nanoTime();
                 command.setGeneratedFileSupport(generatedFilesSupport);
                 command.execute();
+                Duration durationInNs = Duration
+                        .ofNanos(System.nanoTime() - startTime);
+                getLogger().debug("Task [ {} ] completed in {} ms",
+                        command.getClass().getSimpleName(),
+                        durationInNs.toMillis());
             }
         } finally {
             releaseLock();
diff --git a/flow-server/src/main/java/com/vaadin/flow/server/frontend/TaskGeneratePWAIcons.java b/flow-server/src/main/java/com/vaadin/flow/server/frontend/TaskGeneratePWAIcons.java
@@ -17,20 +17,20 @@
 package com.vaadin.flow.server.frontend;
 
 import javax.imageio.ImageIO;
-
 import java.awt.image.BufferedImage;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.UncheckedIOException;
 import java.net.URL;
-import java.net.URLConnection;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -92,11 +92,13 @@ public void execute() throws ExecutionFailedException {
             BufferedImage baseImage = loadBaseImage(iconURL);
             createGeneratedIconsFolder();
 
+            ExecutorService executor = Executors.newFixedThreadPool(4);
             CompletableFuture<?>[] iconsGenerators = PwaRegistry
                     .getIconTemplates(pwaConfiguration.getIconPath()).stream()
                     .map(icon -> new InternalPwaIcon(icon, baseImage))
-                    .map(this::generateIcon).toArray(CompletableFuture[]::new);
-
+                    .map(this::generateIcon)
+                    .map(task -> CompletableFuture.runAsync(task, executor))
+                    .toArray(CompletableFuture[]::new);
             try {
                 CompletableFuture.allOf(iconsGenerators).join();
             } catch (CompletionException ex) {
@@ -111,6 +113,8 @@ public void execute() throws ExecutionFailedException {
             } catch (CancellationException ex) {
                 throw new ExecutionFailedException(
                         "PWA icons generation failed", ex);
+            } finally {
+                executor.shutdown();
             }
         } finally {
             if (headless == null) {
@@ -170,16 +174,16 @@ private URL findIcon(PwaConfiguration pwaConfiguration) {
         return iconURL;
     }
 
-    private CompletableFuture<?> generateIcon(InternalPwaIcon icon) {
+    private Runnable generateIcon(InternalPwaIcon icon) {
         Path iconPath = generatedIconsPath.resolve(icon.getRelHref()
                 .substring(1).replace('/', File.separatorChar));
-        return CompletableFuture.runAsync(() -> {
+        return () -> {
             try (OutputStream os = Files.newOutputStream(iconPath)) {
                 icon.write(os);
             } catch (IOException e) {
                 throw new UncheckedIOException(e);
             }
-        });
+        };
     }
 
     private static class InternalPwaIcon extends PwaIcon {
@@ -194,5 +198,6 @@ public InternalPwaIcon(PwaIcon icon, BufferedImage baseImage) {
         protected BufferedImage getBaseImage() {
             return baseImage;
         }
+
     }
 }
