diff --git a/examples/config/realtime/runtime.properties b/examples/config/realtime/runtime.properties
index cbab843c0e4..4c66f028f67 100644
--- a/examples/config/realtime/runtime.properties
+++ b/examples/config/realtime/runtime.properties
@@ -15,3 +15,4 @@ druid.publish.type=noop
 # druid.db.connector.password=diurd
 
 druid.processing.buffer.sizeBytes=100000000
+druid.processing.numThreads=1