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https://issues.apache.org/jira/browse/SPARK-58107?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SPARK-58107:
-----------------------------------
    Labels: pull-request-available  (was: )

> LocalCheckpoint can be inconsistent because local executor BMs can store 
> inconsistent blocks from task/stage retries
> --------------------------------------------------------------------------------------------------------------------
>
>                 Key: SPARK-58107
>                 URL: https://issues.apache.org/jira/browse/SPARK-58107
>             Project: Spark
>          Issue Type: Bug
>          Components: Spark Core
>    Affects Versions: 4.3.0
>            Reporter: Juliusz Sompolski
>            Priority: Major
>              Labels: pull-request-available
>
> A locally-checkpointed RDD partition can be materialized by more than one 
> successful task attempt — from speculation, or a zombie task of a superseded 
> stage attempt during retries. When the computation is non-deterministic, the 
> attempts produce different bytes for the same RDDBlockId. The BlockManager 
> keeps both copies (the master's blockLocations just appends locations, with 
> no version/attempt id) and a reader picks one at random, so two reads of "the 
> same" local checkpoint can disagree and it is undetected.
> This particularly affects Delta's MERGE source materialization, which 
> localCheckpoints the source DataFrame (a DISK_ONLY serialized level) to cut 
> lineage before the multi-job MERGE. A non-deterministic source (e.g. a source 
> read that isn't stable across attempts) can then be observed inconsistently 
> across the MERGE's passes, surfacing as invariant/row-count violations in the 
> written data.



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