recreate the EventBus on restart to avoid classloader leaks

scm-webapp/src/main/java/sonia/scm/boot/BootstrapContextFilter.java

@@ -39,6 +39,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import sonia.scm.SCMContext;
 import sonia.scm.Stage;
+import sonia.scm.event.RecreateEventBusEvent;
 import sonia.scm.event.ScmEventBus;
 
 import javax.servlet.FilterConfig;
@@ -72,7 +73,7 @@ public class BootstrapContextFilter extends GuiceFilter
    *
    * @throws ServletException
    */
-  @Subscribe(async = false)
+  @Subscribe
   public void handleRestartEvent(RestartEvent event) throws ServletException
   {
     logger.warn("received restart event from {} with reason: {}",
@@ -87,6 +88,10 @@ public class BootstrapContextFilter extends GuiceFilter
       logger.warn("destroy filter pipeline, because of a received restart event");
       destroy();
 
+      logger.warn("send recreate eventbus event");
+      ScmEventBus.getInstance().post(new RecreateEventBusEvent());
+      ScmEventBus.getInstance().register(this);
+
       logger.warn("reinitialize filter pipeline, because of a received restart event");
       initGuice();
     }

scm-webapp/src/main/java/sonia/scm/event/LegmanScmEventBus.java

@@ -36,7 +36,7 @@ package sonia.scm.event;
 //~--- non-JDK imports --------------------------------------------------------
 
 import com.github.legman.EventBus;
-
+import com.github.legman.Subscribe;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -62,9 +62,13 @@ public class LegmanScmEventBus extends ScmEventBus
    * Constructs ...
    *
    */
-  public LegmanScmEventBus()
-  {
-    eventBus = new EventBus(NAME);
+  public LegmanScmEventBus() {
+    eventBus = create();
+  }
+
+  private EventBus create() {
+    logger.info("create new event bus {}", NAME);
+    return new EventBus(NAME);
   }
 
   //~--- methods --------------------------------------------------------------
@@ -118,8 +122,15 @@ public class LegmanScmEventBus extends ScmEventBus
     }
   }
 
+  @Subscribe(async = false)
+  public void recreateEventBus(RecreateEventBusEvent recreateEventBusEvent) {
+    logger.info("shutdown event bus executor");
+    eventBus.shutdown();
+    eventBus = create();
+  }
+
   //~--- fields ---------------------------------------------------------------
 
   /** event bus */
-  private final EventBus eventBus;
+  private EventBus eventBus;
 }

scm-webapp/src/main/java/sonia/scm/event/RecreateEventBusEvent.java

@@ -0,0 +1,7 @@
+package sonia.scm.event;
+
+/**
+ * This event forces the {@link ScmEventBus} to recreate the underlying implementation and to clear all its caches.
+ * Note: After this event is fired, every subscription is removed from the event bus.
+ */
+public final class RecreateEventBusEvent {}