[FLINK-21084] Allows tasks to report finish state

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Implemented
• Fix Version/s: 1.14.0
• Component/s: API / DataStream, Runtime / Checkpointing
• Labels: pull-request-available
• Assignee: Yun Gao
• Reporter: Yun Gao
• Created: 22/Jan/21 03:44
• Updated: 19/Jul/21 06:49
• Resolved: 19/Jul/21 06:49

Description

After we have modified the operator interface to change close to finish and dispose to close, it would become reasonable for operators to continue taking checkpoint after finished() and before closed(). In fact, we would not have checkpoints after operators get closed, thus it would be reasonable to view operator subtasks as FINISHED once the tasks are finished. 

However, there is a special case, if an operator is finished in the restored checkpoints, although in this case we would skip the lifecycle of the operators, the task still need to report a snapshot. Since it is reasonable to keep the operators still be finished in all the following checkpoints, thus the task should tell CheckpointCoordinator about that. Thus we would report a TaskStateSnapshot{isFinished = true} in this case.

Issue Links

• links to: GitHub Pull Request #16238