If more than one task is started in parallel within a workflow and every task is started in a different LIMITED queue, this might lead to Deadlocks and you will see errors similar to these:
A task ends and has 2+ successors. Each successor uses a different queue.
The Automation Engine tries to kick off both successors with a single command.
The order is random, but each of these will generate a queue_check (the FIFO query you see) - if there are multiple running in parallel, this is what causes the deadlock.
Our recommendation is that you upgrade to a ONE Automation version at or above the versions referenced in the Fix version(s) field below should this issue be encountered.
Cause type: Defect Root Cause: Refer to description
Resolution
This field was added on 30/03/2017. This article has not been updated yet. Refer to the "Description" or "Workaround" sections for solution information.