[OAK-3952] BackgroundObserver close should wait for stop to be processed

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: core
• Epic Link: Improve observation resilience
• Assignee: Chetan Mehrotra
• Reporter: Chetan Mehrotra
• Created: 29/Jan/16 07:02
• Updated: 26/Sep/19 11:41

Description

BackgroundObserver close method currently says that it does not wait for thread to finish. This can lead to situation when during shutdown the backing NodeStore goes away while the background thread is still busy with diff and that would lead to exceptions in the log.

As being done in OAK-3923 the close call should wait for STOP signal to be processed before returning from close call.

On side note we should also provide an option where the close call should wait for the queue to be processed instead of just silently clearing the queue which can lead to potential loss of important local events. Note that can happen for proper ordered shutdown!

Issue Links

• relates to: OAK-3923 Async indexing delayed by 30 minutes because stop order is incorrect