diff --git a/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkerTest.java b/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkerTest.java
index bcf9caaeffb..9b174b9b8de 100644
--- a/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkerTest.java
+++ b/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkerTest.java
@@ -345,6 +345,7 @@ public void testThatSettingAttributesTriggerAdditionalResourceChangeEvent() thro
 			IMarker marker = resource.createMarker(TEST_PROBLEM_MARKER);
 			marker.setAttribute(IMarker.MESSAGE, createRandomString());
 			marker.setAttribute(IMarker.PRIORITY, IMarker.PRIORITY_HIGH);
+			TestUtil.waitForCondition(() -> listener.numberOfChanges() == 3, 5000);
 			assertThat(listener.numberOfChanges()).isEqualTo(3);
 		}
 	}
@@ -362,6 +363,7 @@ public void testThatMarkersWithAttributesOnlyTriggerOnResourceChangeEvent() thro
 			// each setAttributes triggers one resource change event
 			resource.createMarker(TEST_PROBLEM_MARKER,
 					Map.of(IMarker.MESSAGE, createRandomString(), IMarker.PRIORITY, IMarker.PRIORITY_HIGH));
+			TestUtil.waitForCondition(() -> listener.numberOfChanges() == 1, 5000);
 			assertThat(listener.numberOfChanges()).isEqualTo(1);
 		}
 	}
diff --git a/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkersChangeListener.java b/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkersChangeListener.java
index 56a831bd7db..0118f0e5f63 100644
--- a/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkersChangeListener.java
+++ b/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkersChangeListener.java
@@ -16,9 +16,12 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-import java.util.HashMap;
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.Vector;
+import java.util.concurrent.ConcurrentHashMap;
 import org.eclipse.core.resources.IMarker;
 import org.eclipse.core.resources.IMarkerDelta;
 import org.eclipse.core.resources.IResource;
@@ -31,7 +34,7 @@
  * A support class for the marker tests.
  */
 public class MarkersChangeListener implements IResourceChangeListener {
-	protected HashMap<IPath, List<IMarkerDelta>> changes;
+	private final Map<IPath, List<IMarkerDelta>> changes = new ConcurrentHashMap<>();
 
 	public MarkersChangeListener() {
 		reset();
@@ -72,11 +75,12 @@ public void assertChanges(IResource resource, IMarker[] added, IMarker[] removed
 	 * changes since last reset.
 	 */
 	public void assertNumberOfAffectedResources(int expectedNumberOfResource) {
+		TestUtil.waitForCondition(() -> changes.size() == expectedNumberOfResource, 5000);
 		assertThat(changes).hasSize(expectedNumberOfResource);
 	}
 
 	public void reset() {
-		changes = new HashMap<>();
+		changes.clear();
 	}
 
 	/**
@@ -96,11 +100,7 @@ protected void resourceChanged(IResourceDelta delta) {
 		}
 		if ((delta.getFlags() & IResourceDelta.MARKERS) != 0) {
 			IPath path = delta.getFullPath();
-			List<IMarkerDelta> v = changes.get(path);
-			if (v == null) {
-				v = new Vector<>();
-				changes.put(path, v);
-			}
+			List<IMarkerDelta> v = changes.computeIfAbsent(path, p -> Collections.synchronizedList(new ArrayList<>()));
 			IMarkerDelta[] markerDeltas = delta.getMarkerDeltas();
 			for (IMarkerDelta markerDelta : markerDeltas) {
 				v.add(markerDelta);
diff --git a/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkersNumberOfDeltasChangeListener.java b/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkersNumberOfDeltasChangeListener.java
index c2f511f7efc..099e2255633 100644
--- a/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkersNumberOfDeltasChangeListener.java
+++ b/resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/MarkersNumberOfDeltasChangeListener.java
@@ -13,6 +13,7 @@
  *******************************************************************************/
 package org.eclipse.core.tests.resources;
 
+import java.util.concurrent.atomic.AtomicInteger;
 import org.eclipse.core.resources.IResourceChangeEvent;
 import org.eclipse.core.resources.IResourceChangeListener;
 
@@ -21,25 +22,25 @@
  */
 public class MarkersNumberOfDeltasChangeListener implements IResourceChangeListener {
 
-	private int number = 0;
+	private AtomicInteger number = new AtomicInteger();
 
 	/**
 	 * Returns the number of resource changed calls.
 	 */
 	public int numberOfChanges() {
-		return number;
+		return number.get();
 	}
 
 
 	public void reset() {
-		number = 0;
+		number.set(0);
 	}
 	/**
 	 * Notification from the workspace.  Extract the marker changes.
 	 */
 	@Override
 	public void resourceChanged(IResourceChangeEvent event) {
-		number++;
+		number.incrementAndGet();
 	}
 
 }