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https://issues.apache.org/jira/browse/FLINK-10333?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Till Rohrmann updated FLINK-10333:
----------------------------------
Description:
While going over the ZooKeeper based stores
({{ZooKeeperSubmittedJobGraphStore}}, {{ZooKeeperMesosWorkerStore}},
{{ZooKeeperCompletedCheckpointStore}}) and the underlying
{{ZooKeeperStateHandleStore}} I noticed several inconsistencies which were
introduced with past incremental changes.
* Depending whether {{ZooKeeperStateHandleStore#getAllSortedByNameAndLock}} or
{{ZooKeeperStateHandleStore#getAllAndLock}} is called, deserialization problems
will either lead to removing the Znode or not
* {{ZooKeeperStateHandleStore}} leaves inconsistent state in case of exceptions
(e.g. {{#getAllAndLock}} won't release the acquired locks in case of a failure)
* {{ZooKeeperStateHandleStore}} has too many responsibilities. It would be
better to move {{RetrievableStateStorageHelper}} out of it for a better
separation of concerns
* {{ZooKeeperSubmittedJobGraphStore}} overwrites a stored {{JobGraph}} even if
it is locked. This should not happen since it could leave another system in an
inconsistent state (imagine a changed {{JobGraph}} which restores from an old
checkpoint)
* Redundant but also somewhat inconsistent put logic in the different stores
* Shadowing of ZooKeeper specific exceptions in {{ZooKeeperStateHandleStore}}
which were expected to be caught in {{ZooKeeperSubmittedJobGraphStore}}
* Getting rid of the {{SubmittedJobGraphListener}} would be helpful
These problems made me think how reliable these components actually work. Since
these components are very important, I propose to refactor them.
was:
While going over the ZooKeeper based stores
({{ZooKeeperSubmittedJobGraphStore}}, {{ZooKeeperMesosWorkerStore}},
{{ZooKeeperCompletedCheckpointStore}}) and the underlying
{{ZooKeeperStateHandleStore}} I noticed several inconsistencies which were
introduced with past incremental changes.
* Depending whether {{ZooKeeperStateHandleStore#getAllSortedByNameAndLock}} or
{{ZooKeeperStateHandleStore#getAllAndLock}} is called, deserialization problems
will either lead to removing the Znode or not
* {{ZooKeeperStateHandleStore}} leaves inconsistent state in case of exceptions
(e.g. {{#getAllAndLock}} won't release the acquired locks in case of a failure)
* {{ZooKeeperStateHandleStore}} has too many responsibilities. It would be
better to move {{RetrievableStateStorageHelper}} out of it for a better
separation of concerns
* {{ZooKeeperSubmittedJobGraphStore}} overwrites a stored {{JobGraph}} even if
it is locked. This should not happen since it could leave another system in an
inconsistent state (imagine a changed {{JobGraph}} which restores from an old
checkpoint)
* Redundant but also somewhat inconsistent put logic in the different stores
* Shadowing of ZooKeeper specific exceptions in {{ZooKeeperStateHandleStore}}
which were expected to be caught in {{ZooKeeperSubmittedJobGraphStore}}
These problems made me think how reliable these components actually work. Since
these components are very important, I propose to refactor them.
> Rethink ZooKeeper based stores (SubmittedJobGraph, MesosWorker,
> CompletedCheckpoints)
> -------------------------------------------------------------------------------------
>
> Key: FLINK-10333
> URL: https://issues.apache.org/jira/browse/FLINK-10333
> Project: Flink
> Issue Type: Bug
> Components: Distributed Coordination
> Affects Versions: 1.5.3, 1.6.0, 1.7.0
> Reporter: Till Rohrmann
> Priority: Major
> Fix For: 1.7.0
>
>
> While going over the ZooKeeper based stores
> ({{ZooKeeperSubmittedJobGraphStore}}, {{ZooKeeperMesosWorkerStore}},
> {{ZooKeeperCompletedCheckpointStore}}) and the underlying
> {{ZooKeeperStateHandleStore}} I noticed several inconsistencies which were
> introduced with past incremental changes.
> * Depending whether {{ZooKeeperStateHandleStore#getAllSortedByNameAndLock}}
> or {{ZooKeeperStateHandleStore#getAllAndLock}} is called, deserialization
> problems will either lead to removing the Znode or not
> * {{ZooKeeperStateHandleStore}} leaves inconsistent state in case of
> exceptions (e.g. {{#getAllAndLock}} won't release the acquired locks in case
> of a failure)
> * {{ZooKeeperStateHandleStore}} has too many responsibilities. It would be
> better to move {{RetrievableStateStorageHelper}} out of it for a better
> separation of concerns
> * {{ZooKeeperSubmittedJobGraphStore}} overwrites a stored {{JobGraph}} even
> if it is locked. This should not happen since it could leave another system
> in an inconsistent state (imagine a changed {{JobGraph}} which restores from
> an old checkpoint)
> * Redundant but also somewhat inconsistent put logic in the different stores
> * Shadowing of ZooKeeper specific exceptions in {{ZooKeeperStateHandleStore}}
> which were expected to be caught in {{ZooKeeperSubmittedJobGraphStore}}
> * Getting rid of the {{SubmittedJobGraphListener}} would be helpful
> These problems made me think how reliable these components actually work.
> Since these components are very important, I propose to refactor them.
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