diff --git a/bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/progress/ProgressViewUpdater.java b/bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/progress/ProgressViewUpdater.java
index 33946a9..3fd3935 100644
--- a/bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/progress/ProgressViewUpdater.java	
+++ b/bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/progress/ProgressViewUpdater.java	
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2003, 2009 IBM Corporation and others.
+ * Copyright (c) 2003, 2012 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -13,7 +13,6 @@ package org.eclipse.ui.internal.progress;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.Iterator;
-
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;
@@ -38,6 +37,16 @@ class ProgressViewUpdater implements IJobProgressManagerListener {
 
     Object updateLock = new Object();
 
+	class MutableBoolean {
+		boolean value;
+	}
+
+	/*
+	 * True when update job is scheduled or running. This is used to limit the
+	 * update job to no more than once every 100 ms.
+	 */
+	MutableBoolean updateScheduled = new MutableBoolean();
+
     boolean debug;
     
    
@@ -217,20 +226,17 @@ class ProgressViewUpdater implements IJobProgressManagerListener {
 		}
     }
 
-    /** keep track of how often we schedule the job to avoid overloading the JobManager */
-    private long lastUpdateJobScheduleRequest = 0;
-    
     /**
      * Schedule an update.
      */
     void scheduleUpdate() {
         if (PlatformUI.isWorkbenchRunning()) {
             // make sure we don't schedule too often
-        	long now = System.currentTimeMillis();
-        	if (now - lastUpdateJobScheduleRequest >= 100) {
-        		//Add in a 100ms delay so as to keep priority low
-        		updateJob.schedule(100);
-        		lastUpdateJobScheduleRequest = now;
+			synchronized (updateScheduled) {
+				if (!updateScheduled.value) {
+					updateScheduled.value = true;
+					updateJob.schedule(100);
+				}
         	}
         }
     }
@@ -246,51 +252,67 @@ class ProgressViewUpdater implements IJobProgressManagerListener {
              * @see org.eclipse.ui.progress.UIJob#runInUIThread(org.eclipse.core.runtime.IProgressMonitor)
              */
             public IStatus runInUIThread(IProgressMonitor monitor) {
-
-                //Abort the job if there isn't anything
-                if (collectors.length == 0) {
-					return Status.CANCEL_STATUS;
-				}
-
-                if (currentInfo.updateAll) {
-                    synchronized (updateLock) {
-                        currentInfo.reset();
-                    }
-                    for (int i = 0; i < collectors.length; i++) {
-                        collectors[i].refresh();
-                    }
-
-                } else {
-                    //Lock while getting local copies of the caches.
-                    Object[] updateItems;
-                    Object[] additionItems;
-                    Object[] deletionItems;
-                    synchronized (updateLock) {
-                        currentInfo.processForUpdate();
-
-                        updateItems = currentInfo.refreshes.toArray();
-                        additionItems = currentInfo.additions.toArray();
-                        deletionItems = currentInfo.deletions.toArray();
-
-                        currentInfo.reset();
-                    }
-
-                    for (int v = 0; v < collectors.length; v++) {
-                        IProgressUpdateCollector collector = collectors[v];
-
-                        if (updateItems.length > 0) {
-							collector.refresh(updateItems);
+				synchronized (updateScheduled) {
+					try {
+						// Abort the job if there isn't anything
+						if (collectors.length == 0) {
+							return Status.CANCEL_STATUS;
 						}
-                        if (additionItems.length > 0) {
-							collector.add(additionItems);
-						}
-                        if (deletionItems.length > 0) {
-							collector.remove(deletionItems);
+
+						if (currentInfo.updateAll) {
+							synchronized (updateLock) {
+								currentInfo.reset();
+							}
+							for (int i = 0; i < collectors.length; i++) {
+								collectors[i].refresh();
+							}
+
+						} else {
+							// Lock while getting local copies of the caches.
+							Object[] updateItems;
+							Object[] additionItems;
+							Object[] deletionItems;
+							synchronized (updateLock) {
+								currentInfo.processForUpdate();
+
+								updateItems = currentInfo.refreshes.toArray();
+								additionItems = currentInfo.additions.toArray();
+								deletionItems = currentInfo.deletions.toArray();
+
+								currentInfo.reset();
+							}
+
+							for (int v = 0; v < collectors.length; v++) {
+								IProgressUpdateCollector collector = collectors[v];
+
+								if (updateItems.length > 0) {
+									collector.refresh(updateItems);
+								}
+								if (additionItems.length > 0) {
+									collector.add(additionItems);
+								}
+								if (deletionItems.length > 0) {
+									collector.remove(deletionItems);
+								}
+							}
 						}
-                    }
-                }
 
-                return Status.OK_STATUS;
+						return Status.OK_STATUS;
+					} finally {
+						updateScheduled.value = false;
+					}
+				}
+			}
+
+			/*
+			 * (non-Javadoc)
+			 * 
+			 * @see org.eclipse.core.runtime.jobs.Job#canceling()
+			 */
+			protected void canceling() {
+				synchronized (updateScheduled) {
+					updateScheduled.value = false;
+				}
             }
         };
         updateJob.setSystem(true);