From 42ffc19df911711b267a3fe21d0cadbaa85af481 Mon Sep 17 00:00:00 2001
From: Janne Valkealahti <janne.valkealahti@gmail.com>
Date: Sun, 5 Nov 2017 17:14:48 +0000
Subject: [PATCH] Fix event processing threading

- Add one extra step to schedule event processing to
  recude risks that machine doesn't do full
  run-to-completion.
- Backport #419
- Relates #420
---
 .../support/DefaultStateMachineExecutor.java             | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/spring-statemachine-core/src/main/java/org/springframework/statemachine/support/DefaultStateMachineExecutor.java b/spring-statemachine-core/src/main/java/org/springframework/statemachine/support/DefaultStateMachineExecutor.java
index 6aee2a2b..65dd4d40 100644
--- a/spring-statemachine-core/src/main/java/org/springframework/statemachine/support/DefaultStateMachineExecutor.java
+++ b/spring-statemachine-core/src/main/java/org/springframework/statemachine/support/DefaultStateMachineExecutor.java
@@ -136,6 +136,9 @@ public class DefaultStateMachineExecutor<S, E> extends LifecycleObjectSupport im
 
 	@Override
 	public void queueDeferredEvent(Message<E> message) {
+		if (log.isDebugEnabled()) {
+			log.debug("Deferring message " + message);
+		}
 		deferList.addLast(message);
 	}
 
@@ -289,7 +292,13 @@ public class DefaultStateMachineExecutor<S, E> extends LifecycleObjectSupport im
 						processTriggerQueue();
 					}
 				}
+
+				if (requestTask.getAndSet(false)) {
+					scheduleEventQueueProcessing();
+				}
 				taskRef.set(null);
+				// do second attempt which should reduse risk
+				// of threading causing failed run to completion
 				if (requestTask.getAndSet(false)) {
 					scheduleEventQueueProcessing();
 				}