diff --git a/jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java b/jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java
index 7a8d4ac23dd..494dbb2ea87 100644
--- a/jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java
+++ b/jetty-io/src/main/java/org/eclipse/jetty/io/SelectChannelEndPoint.java
@@ -22,6 +22,7 @@ import java.nio.channels.CancelledKeyException;
 import java.nio.channels.SelectionKey;
 import java.nio.channels.SocketChannel;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import org.eclipse.jetty.io.SelectorManager.ManagedSelector;
 import org.eclipse.jetty.util.log.Log;
@@ -45,7 +46,7 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements SelectorMa
                 if (getChannel().isOpen())
                 {
                     int oldInterestOps = _key.interestOps();
-                    int newInterestOps = _interestOps;
+                    int newInterestOps = _interestOps.get();
                     if (newInterestOps != oldInterestOps)
                         setKeyInterests(oldInterestOps, newInterestOps);
                 }
@@ -72,7 +73,7 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements SelectorMa
     /**
      * The desired value for {@link SelectionKey#interestOps()}
      */
-    private volatile int _interestOps;
+    private final AtomicInteger _interestOps = new AtomicInteger();
 
     public SelectChannelEndPoint(SocketChannel channel, ManagedSelector selector, SelectionKey key, Scheduler scheduler, long idleTimeout)
     {
@@ -105,6 +106,7 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements SelectorMa
     @Override
     public void onSelected()
     {
+        assert _selector.isSelectorThread();
         int oldInterestOps = _key.interestOps();
         int readyOps = _key.readyOps();
         int newInterestOps = oldInterestOps & ~readyOps;
@@ -119,33 +121,45 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements SelectorMa
 
     private void updateLocalInterests(int operation, boolean add)
     {
-        int oldInterestOps = _interestOps;
-        int newInterestOps;
-        if (add)
-            newInterestOps = oldInterestOps | operation;
-        else
-            newInterestOps = oldInterestOps & ~operation;
-
-        if (isInputShutdown())
-            newInterestOps &= ~SelectionKey.OP_READ;
-        if (isOutputShutdown())
-            newInterestOps &= ~SelectionKey.OP_WRITE;
-
-        if (newInterestOps != oldInterestOps)
+        while (true)
         {
-            _interestOps = newInterestOps;
-            LOG.debug("Local interests updated {} -> {} for {}", oldInterestOps, newInterestOps, this);
-            _selector.submit(_updateTask);
-        }
-        else
-        {
-            LOG.debug("Ignoring local interests update {} -> {} for {}", oldInterestOps, newInterestOps, this);
+            int oldInterestOps = _interestOps.get();
+            int newInterestOps;
+            if (add)
+                newInterestOps = oldInterestOps | operation;
+            else
+                newInterestOps = oldInterestOps & ~operation;
+
+            if (isInputShutdown())
+                newInterestOps &= ~SelectionKey.OP_READ;
+            if (isOutputShutdown())
+                newInterestOps &= ~SelectionKey.OP_WRITE;
+
+            if (newInterestOps != oldInterestOps)
+            {
+                if (_interestOps.compareAndSet(oldInterestOps, newInterestOps))
+                {
+                    LOG.debug("Local interests updated {} -> {} for {}", oldInterestOps, newInterestOps, this);
+                    _selector.submit(_updateTask);
+                }
+                else
+                {
+                    LOG.debug("Local interests update conflict: now {}, was {}, attempted {}", _interestOps.get(), oldInterestOps, newInterestOps);
+                    continue;
+                }
+            }
+            else
+            {
+                LOG.debug("Ignoring local interests update {} -> {} for {}", oldInterestOps, newInterestOps, this);
+            }
+            break;
         }
     }
 
 
     private void setKeyInterests(int oldInterestOps, int newInterestOps)
     {
+        assert _selector.isSelectorThread();
         LOG.debug("Key interests updated {} -> {}", oldInterestOps, newInterestOps);
         _key.interestOps(newInterestOps);
     }
@@ -185,18 +199,20 @@ public class SelectChannelEndPoint extends ChannelEndPoint implements SelectorMa
         // Do NOT use synchronized (this)
         // because it's very easy to deadlock when debugging is enabled.
         // We do a best effort to print the right toString() and that's it.
-        String keyString = "";
-        if (_key.isValid())
+        try
         {
-            if (_key.isReadable())
-                keyString += "r";
-            if (_key.isWritable())
-                keyString += "w";
+            boolean valid = _key.isValid();
+            int keyInterests = valid ? _key.interestOps() : -1;
+            int keyReadiness = valid ? _key.readyOps() : -1;
+            return String.format("%s{io=%d,kio=%d,kro=%d}",
+                    super.toString(),
+                    _interestOps.get(),
+                    keyInterests,
+                    keyReadiness);
         }
-        else
+        catch (CancelledKeyException x)
         {
-            keyString += "!";
+            return String.format("%s{io=%s,kio=-2,kro=-2}", super.toString(), _interestOps.get());
         }
-        return String.format("%s{io=%d,k=%s}",super.toString(), _interestOps, keyString);
     }
 }
diff --git a/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java b/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java
index 2463a0c0afc..1aab8ba7698 100644
--- a/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java
+++ b/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java
@@ -516,6 +516,11 @@ public abstract class SelectorManager extends AbstractLifeCycle implements Dumpa
             _selector.wakeup();
         }
 
+        public boolean isSelectorThread()
+        {
+            return Thread.currentThread() == _thread;
+        }
+
         private EndPoint createEndPoint(SocketChannel channel, SelectionKey selectionKey) throws IOException
         {
             EndPoint endPoint = newEndPoint(channel, this, selectionKey);