[BEAM-2504] Processing time timers with timestamp past GC time are interpreted as GC timers

• Type: Bug
• Status: Resolved
• Priority: P0
• Resolution: Fixed
• Fix Version/s: 2.1.0
• Component/s: runner-core
• Assignee: Kenneth Knowles
• Reporter: Kenneth Knowles
• Created: 22/Jun/17 18:46
• Updated: 16/May/20 14:20
• Resolved: 23/Jun/17 00:03

Description

The affects accumulating mode most acutely: when a processing time trigger fires and processing is ahead of the watermark (which it usually will be) there will be a final pane from the premature GC. Then, if no more data comes in, the GC timer fires and outputs another pane marked "final" but this time with an empty (aka zero) accumulator. This is a likely scenario since the processing time timer is probably just a smidge ahead of the watermark. So any sink writing the accumulated value will fill with zeros mostly, some correct values, and other values that are just the data from the last moments before GC.

This would also have a severe affect on merging windows, since merging terminates upon GC.