flutter · Copilot · Aug 20, 2025 · Aug 20, 2025 · Aug 20, 2025
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -12,6 +12,7 @@
 - Made dev release daily instead of weekly
 - Set the device selector component to opaque during its creation to avoid an unexpected background color (#8471)
 - Refactored `DeviceSelectorAction` and add rich icons to different platform devices (#8475)
+- Fix EDT freezes when opening embedded DevTools and on theme change (#8477)
 
 ## 87.1.0
 

diff --git a/src/io/flutter/FlutterInitializer.java b/src/io/flutter/FlutterInitializer.java
@@ -60,7 +60,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicLong;
 
@@ -78,6 +78,10 @@ public class FlutterInitializer extends FlutterProjectActivity {
 
   private @NotNull AtomicLong lastScheduledThemeChangeTime = new AtomicLong();
 
+  // Shared scheduler to avoid creating/closing executors on EDT
+  @NotNull
+  private final ScheduledExecutorService scheduler = AppExecutorUtil.getAppScheduledExecutorService();
+
   @Override
   public void executeProjectStartup(@NotNull Project project) {
     log().info("Executing Flutter plugin startup for project: " + project.getName());
@@ -253,57 +257,55 @@ private void sendThemeChangedEvent(@NotNull Project project) {
     lastScheduledThemeChangeTime.set(requestTime);
 
     // Schedule event to be sent in a second if nothing more recent has come in.
-    try (var executor = Executors.newSingleThreadScheduledExecutor()) {
-      executor.schedule(() -> {
-        if (lastScheduledThemeChangeTime.get() != requestTime) {
-          // A more recent request has been set, so drop this request.
+    scheduler.schedule(() -> {
+      if (lastScheduledThemeChangeTime.get() != requestTime) {
+        // A more recent request has been set, so drop this request.
+        return;
+      }
+
+      final JsonObject params = new JsonObject();
+      params.addProperty("eventKind", "themeChanged");
+      params.addProperty("streamId", "Editor");
+
+      final JsonObject themeData = new JsonObject();
+      final DevToolsUtils utils = new DevToolsUtils();
+      themeData.addProperty("isDarkMode", Boolean.FALSE.equals(utils.getIsBackgroundBright()));
+      themeData.addProperty("backgroundColor", utils.getColorHexCode());
+      themeData.addProperty("fontSize", utils.getFontSize().intValue());
+
+      final JsonObject eventData = new JsonObject();
+      eventData.add("theme", themeData);
+      params.add("eventData", eventData);
+
+      try {
+        final DtdUtils dtdUtils = new DtdUtils();
+        final DartToolingDaemonService dtdService = dtdUtils.readyDtdService(project).get();
+        if (dtdService == null) {
+          log().error("Unable to send theme changed event because DTD service is null");
           return;
         }
 
-        final JsonObject params = new JsonObject();
-        params.addProperty("eventKind", "themeChanged");
-        params.addProperty("streamId", "Editor");
-
-        final JsonObject themeData = new JsonObject();
-        final DevToolsUtils utils = new DevToolsUtils();
-        themeData.addProperty("isDarkMode", Boolean.FALSE.equals(utils.getIsBackgroundBright()));
-        themeData.addProperty("backgroundColor", utils.getColorHexCode());
-        themeData.addProperty("fontSize", utils.getFontSize().intValue());
-
-        final JsonObject eventData = new JsonObject();
-        eventData.add("theme", themeData);
-        params.add("eventData", eventData);
-
-        try {
-          final DtdUtils dtdUtils = new DtdUtils();
-          final DartToolingDaemonService dtdService = dtdUtils.readyDtdService(project).get();
-          if (dtdService == null) {
-            log().error("Unable to send theme changed event because DTD service is null");
-            return;
-          }
-
-          dtdService.sendRequest("postEvent", params, false, object -> {
-                                   JsonObject result = object.getAsJsonObject("result");
-                                   if (result == null) {
-                                     log().error("Theme changed event returned null result");
-                                     return;
-                                   }
-                                   JsonPrimitive type = result.getAsJsonPrimitive("type");
-                                   if (type == null) {
-                                     log().error("Theme changed event result type is null");
-                                     return;
-                                   }
-                                   if (!"Success".equals(type.getAsString())) {
-                                     log().error("Theme changed event result: " + type.getAsString());
-                                   }
+        dtdService.sendRequest("postEvent", params, false, object -> {
+                                 JsonObject result = object.getAsJsonObject("result");
+                                 if (result == null) {
+                                   log().error("Theme changed event returned null result");
+                                   return;
                                  }
-          );
-        }
-        catch (WebSocketException | InterruptedException | ExecutionException e) {
-          log().error("Unable to send theme changed event", e);
-        }
-      }, 1, TimeUnit.SECONDS);
-    }
+                                 JsonPrimitive type = result.getAsJsonPrimitive("type");
+                                 if (type == null) {
+                                   log().error("Theme changed event result type is null");
+                                   return;
+                                 }
+                                 if (!"Success".equals(type.getAsString())) {
+                                   log().error("Theme changed event result: " + type.getAsString());
+                                 }
+                               }
+        );
+      }
+      catch (WebSocketException | InterruptedException | ExecutionException e) {
+        log().error("Unable to send theme changed event", e);
+      }
+    }, 1, TimeUnit.SECONDS);
   }
 
   private void checkSdkVersionNotification(@NotNull Project project) {

diff --git a/src/io/flutter/jxbrowser/EmbeddedJxBrowser.java b/src/io/flutter/jxbrowser/EmbeddedJxBrowser.java
@@ -129,6 +129,8 @@ public class EmbeddedJxBrowser extends EmbeddedBrowser {
     "Waiting for JxBrowser installation timed out. Restart your IDE to try again.";
   private static final String INSTALLATION_WAIT_FAILED = "The JxBrowser installation failed unexpectedly. Restart your IDE to try again.";
   private static final int INSTALLATION_WAIT_LIMIT_SECONDS = 30;
+
+  @NotNull
   private final AtomicReference<Engine> engineRef = new AtomicReference<>(null);
 
   private final Project project;
@@ -173,19 +175,14 @@ private EmbeddedJxBrowser(@NotNull Project project) {
   }
 
   @Override
-  public @Nullable EmbeddedTab openEmbeddedTab(ContentManager contentManager) {
+  public @Nullable EmbeddedTab openEmbeddedTab(@NotNull ContentManager contentManager) {
     manageJxBrowserDownload(contentManager);
-    if (engineRef.get() == null) {
-      engineRef.compareAndSet(null, EmbeddedBrowserEngine.getInstance().getEngine());
-    }
     final Engine engine = engineRef.get();
     if (engine == null) {
-      showMessageWithUrlLink(jxBrowserErrorMessage(), contentManager);
+      handleJxBrowserInstallationInProgress(contentManager);
       return null;
     }
-    else {
-      return new EmbeddedJxBrowserTab(engine);
-    }
+    return new EmbeddedJxBrowserTab(engine);
   }
 
   private @NotNull String jxBrowserErrorMessage() {

diff --git a/testSrc/unit/io/flutter/FlutterInitializerTest.java b/testSrc/unit/io/flutter/FlutterInitializerTest.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2016 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+package io.flutter;
+
+import org.junit.Test;
+
+import java.lang.reflect.Field;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Tests for {@link FlutterInitializer}.
+ */
+public class FlutterInitializerTest {
+
+  @Test
+  public void testInitializerCanBeCreated() {
+    // Test that we can create FlutterInitializer without issues
+    // This validates that the shared scheduler field is properly initialized
+    FlutterInitializer initializer = new FlutterInitializer();
+    assertNotNull("FlutterInitializer should be created successfully", initializer);
+  }
+
+  @Test
+  public void testSchedulerFieldExists() throws Exception {
+    // Test that the scheduler field exists and is properly initialized
+    FlutterInitializer initializer = new FlutterInitializer();
+
+    Field schedulerField = FlutterInitializer.class.getDeclaredField("scheduler");
+    schedulerField.setAccessible(true);
+
+    Object scheduler = schedulerField.get(initializer);
+    assertNotNull("Scheduler field should be initialized", scheduler);
+    assertTrue("Scheduler should be a ScheduledExecutorService", 
+               scheduler instanceof ScheduledExecutorService);
+  }
+
+  @Test 
+  public void testDebounceFieldExists() throws Exception {
+    // Test that the debounce field exists and is properly initialized
+    FlutterInitializer initializer = new FlutterInitializer();
+
+    Field debounceField = FlutterInitializer.class.getDeclaredField("lastScheduledThemeChangeTime");
+    debounceField.setAccessible(true);
+
+    Object debounceTimer = debounceField.get(initializer);
+    assertNotNull("Debounce timer field should be initialized", debounceTimer);
+    assertTrue("Debounce timer should be an AtomicLong", 
+               debounceTimer instanceof AtomicLong);
+  }
+}