Roman Khachatryan created FLINK-23461:
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             Summary: Consider disallowing in-memory state handles for 
materialized state
                 Key: FLINK-23461
                 URL: https://issues.apache.org/jira/browse/FLINK-23461
             Project: Flink
          Issue Type: Sub-task
          Components: Runtime / State Backends
            Reporter: Roman Khachatryan
             Fix For: 1.14.0


*For non-mateialized part*, FLINK-21353 doesn't use nor 
FsCheckpointStreamFactory neither PlaceholderStreamStateHandle so it's not an 
issue. Adding it in the future doesn't make sense as for such small changes 
incremental checkpoint might work better.

*For materialized part, ByteStreamStateHandle* can be currently used. This can 
bring back to life issues like FLINK-21351 - if checkpoint subsumption on TM 
*will* be decoupled from the state backends state. Removing those assumptions 
is one of the goals of changing the ownership.
 An easy way to solve it is to just enforce zero threshold for writing to DFS 
instead of memory.

 

*PlaceholderStreamStateHandle* can be used for the materialized state 
(regardless of ByteStreamStateHandle; unless SnapshotStrategy is changed). 
However, it shouldn't cause any issues:
 - if the file is shared (i.e. after recovery) then by definition it should be 
managed by JM
 - otherwise, JM should still replace placeholders (FLINK-23137); and it should 
have received the original state objects before; no re-upload should happen 
(FLINK-23344) - so JM and TM will always refer to the same file



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