[NIFI-6820] If Processor adjusts a counter but does not interact with any FlowFiles, the counter isn't updated

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.13.0
• Component/s: Core Framework
• Labels: beginner easyfix newbie
• Assignee: Hsin-Ying Lee
• Reporter: Mark Payne
• Created: 29/Oct/19 14:15
• Updated: 19/Jul/21 16:12
• Resolved: 13/Nov/20 16:26

Description

If a Processor calls `ProcessSession.adjustCounter` and passes `false` for the `immediate` argument, the adjustment for the counter should be maintained by the ProcessSession. Then, when (if) the session is committed, the counter should actually be updated. However, if the Processor never interacts with any FlowFiles (never calls `get()` or `create()`), then the counter never gets updated.

This appears to be due to the fact that in the `checkpoint` method, `StandardProcessSession` checks if `records.isEmpty()` and if so returns. In such a case, it needs to first ensure that it transfers the counters to the checkpoint before returning.

Issue Links

• relates to: NIFI-6800 StandardProcessSession error - hashmap counter overwritten in highThroughputSession
• links to: GitHub Pull Request #4663