Fix JMX MBean leak during Jetty restart cycle

Call MBeanContainer.destroy() in MBeanServerTracker.removedService() to
unregister all JMX MBeans before removing the event listener. Also move
the MBeanServerTracker cleanup in stopJetty() to before server.stop()
so MBeans are unregistered while the Server instance is still valid.

Without this fix, restarting Jetty leaves stale MBean registrations
(e.g. org.eclipse.jetty.server:type=server,id=0) in the platform
MBeanServer, causing an InstanceAlreadyExistsException on the next
startup cycle.

Author: francescomari

http/jetty/src/main/java/org/apache/felix/http/jetty/internal/JettyService.java

@@ -245,6 +245,12 @@ private void stopJetty()
                 this.loadBalancerCustomizerTracker = null;
             }
 
+            if (this.mbeanServerTracker != null)
+            {
+                this.mbeanServerTracker.close();
+                this.mbeanServerTracker = null;
+            }
+
             try
             {
                 this.server.stop();
@@ -255,12 +261,6 @@ private void stopJetty()
             {
                 SystemLogger.LOGGER.error("Exception while stopping Jetty", e);
             }
-
-            if (this.mbeanServerTracker != null)
-            {
-                this.mbeanServerTracker.close();
-                this.mbeanServerTracker = null;
-            }
         }
     }
 

http/jetty/src/main/java/org/apache/felix/http/jetty/internal/MBeanServerTracker.java

@@ -59,6 +59,7 @@ public void removedService(ServiceReference<MBeanServer> reference, MBeanContain
     {
         if ( service != null )
         {
+            service.destroy();
             this.server.removeEventListener(service);
             super.removedService(reference, service);
         }

http/jetty12/src/main/java/org/apache/felix/http/jetty/internal/JettyService.java

@@ -255,6 +255,12 @@ private void stopJetty()
                 this.loadBalancerCustomizerTracker = null;
             }
 
+            if (this.mbeanServerTracker != null)
+            {
+                this.mbeanServerTracker.close();
+                this.mbeanServerTracker = null;
+            }
+
             try
             {
                 this.server.stop();
@@ -265,12 +271,6 @@ private void stopJetty()
             {
                 SystemLogger.LOGGER.error("Exception while stopping Jetty", e);
             }
-
-            if (this.mbeanServerTracker != null)
-            {
-                this.mbeanServerTracker.close();
-                this.mbeanServerTracker = null;
-            }
         }
     }
 

http/jetty12/src/main/java/org/apache/felix/http/jetty/internal/MBeanServerTracker.java

@@ -59,6 +59,7 @@ public void removedService(ServiceReference<MBeanServer> reference, MBeanContain
     {
         if ( service != null )
         {
+            service.destroy();
             this.server.removeEventListener(service);
             super.removedService(reference, service);
         }