[NIFI-6879] Variable Update Error when trying to change outside variable used inside a Process Group

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.10.0
• Fix Version/s: 1.11.0
• Component/s: Core Framework
• Environment: Host OS: Ubuntu 16.04 ; Docker version 19.03.4, build 9013bf583a ; Docker Image: apache/nifi 1.10.0 4310dad3312f
• Assignee: Mark Payne
• Reporter: Marcio Sugar
• Created: 18/Nov/19 15:49
• Updated: 24/Jan/20 05:02
• Resolved: 26/Dec/19 17:06

Description

This works fine in NiFi 1.7.1 but fails in NiFi 1.10.1.

Whenever I try to change the value of a variable that's defined outside a Process Group where it's used, NiFi fails during the Applying Updates with the following message (image also attached):

Variable Update Error
Unable to complete variable update request: Failed to update Variable Registry because failed while performing step: Applying updates to Variable Registry.

To reproduce the problem:

1. On the top-level canvas, create a variable named "myvar", and set it to "blah".
2. Create a Process Group named "mypg".  Enter the group. 
3. Inside "mypg", add a GenerateFlowFile and set its "Run Schedule" to "1 day" to get just one flow file when it's started.
4. Still inside "mypg", add a LogMessage. Set its "Log prefix" to "MYLOG: " and its "Log message" to "My message is: '${myvar}'."
5. Start both processors and see a message like this appeared in the application's log:  MYLOG: My message is: 'blah'.
6. Now leave the "mypg" Process Group and go back to the top-level canvas. Try to set the "myvar" variable to a different value, like "blah-blah", and hit "Apply". NiFi starts the steps to make the change, but fails during the "Applying Updates" step with the above error message. In the log, the following error message appears:

ERROR [Variable Registry Update Thread] o.a.nifi.web.api.ProcessGroupResource Failed to update variable registry for Process Group with ID 7f16c8da-016e-1000-aeb0-e65ea5e5f889
java.lang.IllegalStateException: Cannot update variable 'myvar' because it is referenced by 1 components that are currently running. 

Images and log file attached. The log file has the full exception trace.

 

Issue Links

• duplicates: NIFI-6844 Unable to update NiFi Variables despite stopping all processors
• is caused by: NIFI-6194 Updating variables does not properly resolve referencing components causing variable updates to incorrectly fail
• links to: GitHub Pull Request #3949