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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-4512) Add option for persistent checkpoints
Date Tue, 11 Oct 2016 14:17:21 GMT

    [ https://issues.apache.org/jira/browse/FLINK-4512?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15565538#comment-15565538
] 

ASF GitHub Bot commented on FLINK-4512:
---------------------------------------

Github user tillrohrmann commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2608#discussion_r82784524
  
    --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/checkpoint/StandaloneCompletedCheckpointStore.java
---
    @@ -64,9 +62,9 @@ public void recover() throws Exception {
     
     	@Override
     	public void addCheckpoint(CompletedCheckpoint checkpoint) throws Exception {
    -		checkpoints.addLast(checkpoint);
    +		checkpoints.add(checkpoint);
     		if (checkpoints.size() > maxNumberOfCheckpointsToRetain) {
    -			checkpoints.removeFirst().discardState();
    +			checkpoints.remove().subsume();
    --- End diff --
    
    What happens if the `CheckpointProperties.discardOnSubsumed() == false`. This could lead
to files in your nfs which are not cleaned up even though they are not useful for anything
else (given that it's not a persistent checkpoint), right?


> Add option for persistent checkpoints
> -------------------------------------
>
>                 Key: FLINK-4512
>                 URL: https://issues.apache.org/jira/browse/FLINK-4512
>             Project: Flink
>          Issue Type: Sub-task
>          Components: State Backends, Checkpointing
>            Reporter: Ufuk Celebi
>            Assignee: Ufuk Celebi
>
> Allow periodic checkpoints to be persisted by writing out their meta data. This is what
we currently do for savepoints, but in the future checkpoints and savepoints are likely to
diverge with respect to guarantees they give for updatability, etc.
> This means that the difference between persistent checkpoints and savepoints in the long
term will be that persistent checkpoints can only be restored with the same job settings (like
parallelism, etc.)
> Regular and persisted checkpoints should behave differently with respect to disposal
in *globally* terminal job states (FINISHED, CANCELLED, FAILED): regular checkpoints are cleaned
up in all of these cases whereas persistent checkpoints only on FINISHED. Maybe with the option
to customize behaviour on CANCELLED or FAILED.



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