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https://issues.apache.org/jira/browse/BEAM-7192?focusedWorklogId=236203&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-236203
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ASF GitHub Bot logged work on BEAM-7192:
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Author: ASF GitHub Bot
Created on: 02/May/19 10:11
Start Date: 02/May/19 10:11
Worklog Time Spent: 10m
Work Description: mxm commented on issue #8441: [BEAM-7192] Fix
partitioning of buffered elements during checkpointing
URL: https://github.com/apache/beam/pull/8441#issuecomment-488620160
There are two threads:
1. Main operator thread which emits elements and buffers them in the state
backend
2. GRPC thread which delegates state requests of pending elements to the
state backend
So there can be concurrent writes to the state backend which must be
avoided. We don't need the lock in case only the main operator thread can have
access, as it is the case for `flushBuffer()` where the bundle is ensured to be
finished. That's why there is only a lock in the `buffer` method.
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Issue Time Tracking
-------------------
Worklog Id: (was: 236203)
Time Spent: 1h 20m (was: 1h 10m)
> Elements buffered during checkpointing may not be partitioned correctly
> -----------------------------------------------------------------------
>
> Key: BEAM-7192
> URL: https://issues.apache.org/jira/browse/BEAM-7192
> Project: Beam
> Issue Type: Bug
> Components: runner-flink
> Reporter: Maximilian Michels
> Assignee: Maximilian Michels
> Priority: Major
> Fix For: 2.13.0
>
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> When a Flink checkpoint is taken, the current bundle is finalized. The
> finalization happens when the checkpoint barrier has already been sent
> downstream; emitting elements at this point would violate the checkpoint
> barrier alignment.
> When elements are emitted during checkpointing they are buffered until the
> checkpoint is complete. We should ensure that they are keyed correctly and
> emission of the buffered elements does not interfere with any concurrent
> state requests (in case of portability).
>
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