Fix race condition in AbstractReconciler.reset() event ordering

bundles/org.eclipse.jface.text/src/org/eclipse/jface/text/reconciler/AbstractReconciler.java

@@ -140,29 +140,27 @@ public void suspendCallerWhileDirty() {
 		 */
 		public void reset() {
 
+			reconcilerReset();
+
 			if (fDelay > 0) {
 
 				synchronized (this) {
 					fIsDirty= true;
 					fReset= true;
 				}
-				synchronized (fDirtyRegionQueue) {
-					fDirtyRegionQueue.notifyAll(); // wake up wait(fDelay);
-				}
 
 			} else {
 
 				synchronized (this) {
 					fIsDirty= true;
 				}
-
-				synchronized (fDirtyRegionQueue) {
-					fDirtyRegionQueue.notifyAll();
-				}
 			}
 
 			informNotFinished();
-			reconcilerReset();
+
+			synchronized (fDirtyRegionQueue) {
+				fDirtyRegionQueue.notifyAll();
+			}
 		}
 
 		/**

tests/org.eclipse.jface.text.tests/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %Plugin.name
 Bundle-SymbolicName: org.eclipse.jface.text.tests
-Bundle-Version: 3.14.0.qualifier
+Bundle-Version: 3.14.100.qualifier
 Bundle-Vendor: %Plugin.providerName
 Bundle-Localization: plugin
 Export-Package: 

tests/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/JFaceTextTestSuite.java

@@ -26,6 +26,7 @@
 import org.eclipse.jface.text.tests.contentassist.IncrementalAsyncContentAssistTests;
 import org.eclipse.jface.text.tests.reconciler.AbstractReconcilerTest;
 import org.eclipse.jface.text.tests.reconciler.FastAbstractReconcilerTest;
+import org.eclipse.jface.text.tests.reconciler.ReconcilerResetOrderingTest;
 import org.eclipse.jface.text.tests.rules.FastPartitionerTest;
 import org.eclipse.jface.text.tests.rules.FastPartitionerZeroLengthTest;
 import org.eclipse.jface.text.tests.rules.ScannerColumnTest;
@@ -61,6 +62,7 @@
 
 		AbstractReconcilerTest.class,
 		FastAbstractReconcilerTest.class,
+		ReconcilerResetOrderingTest.class,
 
 		FastPartitionerZeroLengthTest.class,
 		FastPartitionerTest.class,

tests/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/reconciler/AbstractReconcilerTest.java

@@ -173,6 +173,7 @@ protected void aboutToBeReconciled() {
 					}
 					@Override
 					protected void reconcilerReset() {
+						AbstractReconcilerTest.this.beforeReconcilerResetLogged();
 						fCallLog.add("reconcilerReset");
 					}
 					@Override
@@ -202,6 +203,10 @@ void aboutToWork(@SuppressWarnings("unused") AbstractReconciler reconciler) {
 		// nothing
 	}
 
+	void beforeReconcilerResetLogged() {
+		// hook for subclasses to widen race window
+	}
+
 	@AfterEach
 	public void tearDown() throws Exception {
 		fBarrier.shutdown();

tests/org.eclipse.jface.text.tests/src/org/eclipse/jface/text/tests/reconciler/ReconcilerResetOrderingTest.java

@@ -0,0 +1,40 @@
+/*******************************************************************************
+ * Copyright (c) 2025 Contributors to the Eclipse Foundation.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.jface.text.tests.reconciler;
+
+import org.eclipse.jface.text.reconciler.AbstractReconciler;
+
+/**
+ * Regression test for the race condition in
+ * {@link AbstractReconciler#install BackgroundWorker.reset()} where
+ * {@code reconcilerReset()} could be called after the background thread was
+ * already notified, allowing {@code process()} to run before the reset hook.
+ * <p>
+ * This test widens the race window by introducing a 50ms delay before logging
+ * {@code reconcilerReset}. Without the fix (reconcilerReset called before queue
+ * notification), the background thread is already awake during the delay and
+ * reaches {@code process()} first, causing {@code testReplacingDocumentWhenClean}
+ * to deterministically fail.
+ * </p>
+ *
+ * @see <a href="https://github.com/eclipse-platform/eclipse.platform.ui/issues/2708">Issue 2708</a>
+ */
+public class ReconcilerResetOrderingTest extends FastAbstractReconcilerTest {
+
+	@Override
+	void beforeReconcilerResetLogged() {
+		try {
+			Thread.sleep(50);
+		} catch (InterruptedException e) {
+			Thread.currentThread().interrupt();
+		}
+	}
+}