Hello!
We have encountered an issue that I was able to replicate in a simple process model. (Refer to the screenshot below)
We had a completed instance that skipped the "True" node, we wanted to edit the conditions so this node is executed, so the conditions were swapped (in Edit mode) and we restarted the "Script Task" node (in Monitoring mode) since gateways cannot be restarted and the flow got stuck in the "Gateway 2" without any errors.
There are no process variables or rules. We are using Appian 19.1.
The steps are the following:
- Build a process model with two gateways. (Similar to the example above)
- Run an instance and let it finish
- Edit the previous instance and swap the conditions in the second gateway configuration. (in Edit mode) Click File > Apply Changes
- Restart the first "Script Task" node (in Monitoring mode)
- The process gets stuck in the second gateway. (Stays green) There are no errors in the process nor the logs. The process remains "Active" not paused or paused with an exception.
Any insights?
Thanks!
Discussion posts and replies are publicly visible
Hi,
This is due to the fact that "Gateway 2" has two incoming flows. From the documentation on XOR gateways (https://docs.appian.com/suite/help/19.1/XOR_Node.html):
"When multiple incoming flows are connected to the XOR gateway, it allows the first flow token through to an exclusive outgoing flow. Subsequent flow tokens wait for all incoming flows to arrive before executing the output flow decision."
Hope this helps!
Dan
Hi Dan,
Thanks for your response.
Interesting, so this means the first time the gateway is executed with only one incoming path but the second time it waits for all incoming paths?
If so, I tried adding a "Dummy" node before Gateway 2 to receive both inputs but I ran into the same problem again, the process is stuck in Gateway 2.
Any ideas?
Thanks,
Aby
That is my understanding. With the dummy node in place, which node was it that you started after the process instance completed the first time? The new "Dummy" script task?
I previously restarted the "Script Task" node and it got stuck again.
But I just tried to restart the "Dummy" node now and it went through!
(Restarting Dummy node)
I'm not sure I why this happened but it's good to know it finally got to the node I wanted.
Thanks a lot for your help, Dan! :)