Allow concurrent events

PiperOrigin-RevId: 221261799
diff --git a/src/main/java/com/google/devtools/build/lib/runtime/BuildSummaryStatsModule.java b/src/main/java/com/google/devtools/build/lib/runtime/BuildSummaryStatsModule.java
index d2fb6cb..cd782bd 100644
--- a/src/main/java/com/google/devtools/build/lib/runtime/BuildSummaryStatsModule.java
+++ b/src/main/java/com/google/devtools/build/lib/runtime/BuildSummaryStatsModule.java
@@ -15,6 +15,7 @@
 
 import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
+import com.google.common.eventbus.AllowConcurrentEvents;
 import com.google.common.eventbus.EventBus;
 import com.google.common.eventbus.Subscribe;
 import com.google.devtools.build.lib.actions.ActionKeyContext;
@@ -86,6 +87,7 @@
   }
 
   @Subscribe
+  @AllowConcurrentEvents
   public void actionResultReceived(ActionResultReceivedEvent event) {
     spawnStats.countActionResult(event.getActionResult());
   }