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https://issues.apache.org/jira/browse/FLINK-14344?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16961729#comment-16961729
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Biao Liu commented on FLINK-14344:
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[~pnowojski], thanks a lot for feedback.
{quote}After the refactor, it would block whole JobManager, right?{quote}
Yes, you are right. It might cause a performance issue if the hook executes a
time-consuming operation.
I have taken a look at the Pravega connector codes. The current implementation
of {{MasterTriggerRestoreHook.triggerCheckpoint}} is executed asynchronously
with an internal {{ScheduledExecutorService}}, not the IO executor provided.
It's acceptable for us. I have left a message to the guys of this project [1].
I hope they could give me a feedback.
Regarding to the "two possible semantics". I'm afraid we have to choose option
2 due to compatibility. There is a comment of
{{MasterTriggerRestoreHook.triggerCheckpoint}}:
{quote}This method is called by the checkpoint coordinator prior when
triggering a checkpoint, prior to sending the "trigger checkpoint" messages to
the source tasks{quote}
[1] https://github.com/pravega/flink-connectors/issues/287
> Snapshot master hook state asynchronously
> -----------------------------------------
>
> Key: FLINK-14344
> URL: https://issues.apache.org/jira/browse/FLINK-14344
> Project: Flink
> Issue Type: Sub-task
> Components: Runtime / Checkpointing
> Reporter: Biao Liu
> Assignee: Biao Liu
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.10.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Currently we snapshot the master hook state synchronously. As a part of
> reworking threading model of {{CheckpointCoordinator}}, we have to make this
> non-blocking to satisfy the requirement of running in main thread.
> The behavior of snapshotting master hook state is similar to task state
> snapshotting. Master state snapshotting is taken before task state
> snapshotting. Because in master hook, there might be external system
> initialization which task state snapshotting might depend on.
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