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https://issues.apache.org/jira/browse/FLINK-22676?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17355141#comment-17355141
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Jin Xing commented on FLINK-22676:
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Hi, Till ~ Yes, I think we are on the same page -- we are discussing how should
JMPartitionTracker manage partitions properly ~
{quote}If the ShuffleMaster should lose a result partition, then a reading task
should fail with a PartitionException which will invalidate the partition on
the JobMasterPartitionTracker so that it is reproduced.
{quote}
1. True, the reproduction of a lost upstream partition could be triggered by
the shuffle-read failure of downstream. But it tends to be unacceptable in
production environment for batch processing job. Say there are 100 upstream
partitions are lost due to failure of an external shuffle worker, if there's no
notification from ShuffleMaster to JMPartitionTracker, 100
_PartitionExceptions_ on downstream will happen and upstream partitions will be
reproduced one by one sequentially. The time overhead will be unacceptable.
From this point of view, I tend to think ShuffleMaster should have the ability
to unregister partitions by locationID on JMPartitionTracker.
{quote}I think that deciding whether the partition is stored externally or not
can be answered by using the ShuffleDescriptor.storesLocalResourcesOn method.
{quote}
2. Yes, I agree it works (though it's not easy to access ShuffleDescriptor by
_tmID_ from JMPartitionTracker at this moment). But if we agree that my first
point is valid, JMPartitionTracker should maintain the index from _locationID_
to partition. Then it will be straightforward to check whether a partition is
accommodated on remote by comparing its _tmID_ and _locationID_;
> The partition tracker should support remote shuffle properly
> ------------------------------------------------------------
>
> Key: FLINK-22676
> URL: https://issues.apache.org/jira/browse/FLINK-22676
> Project: Flink
> Issue Type: Sub-task
> Components: Runtime / Coordination, Runtime / Network
> Reporter: Jin Xing
> Priority: Major
>
> In current Flink, data partition is bound with the ResourceID of TM in
> Execution#startTrackingPartitions and partition tracker will stop tracking
> corresponding partitions when a TM
> disconnects(JobMaster#disconnectTaskManager), i.e. the lifecycle of shuffle
> data is bound with computing resource (TM). It works fine for internal
> shuffle service, but doesn't for remote shuffle service. Note that shuffle
> data is accommodated on remote, the lifecycle of a completed partition is
> capable to be decoupled with TM, i.e. TM is totally fine to be released when
> no computing task on it and further shuffle reading requests could be
> directed to remote shuffle cluster. In addition, when a TM is lost, its
> completed data partitions on remote shuffle cluster could avoid reproducing.
>
> The issue mentioned above is because Flink JobMasterPartitionTracker mixed up
> partition's locationID (where the partition is located) and tmID (which TM
> the partition is produced from). In TM internal shuffle, partition's
> locationID is the same with tmID, but it is not in remote shuffle;
> JobMasterPartitionTracker as an independent component should be able to
> differentiate locationID and tmID of a partition, thus to handle the
> lifecycle of a partition properly;
> We propose that JobMasterPartitionTracker manages and indexes partitions with
> both locationID and tmID. The process of registration and unregistration will
> be like below:
> *A. Partiiton Registration*
> # Execution#registerProducedPartitions registers partition to ShuffleMaster
> and get a ShuffleDescriptor. Current ShuffleDescriptor#storesLocalResourcesOn
> only returns the location of the producing TM if the partition occupies local
> resources there.
> We proposes to change a proper name of this method and always return the
> locationID of the partition. It might be as below:
> {code:java}
> ResourceID getLocationID(); {code}
> # Execution#registerProducePartitions then registers partition to
> JMPartitionTracker with tmID (ResourceID of TaskManager from
> TaskManagerLocation) and the locationID (acquired in step 1).
> JobMasterPartitionTracker will indexes a partition with both tmID and
> locationID;
> *B. Invokes from JM and ShuffleMaster*
> JobMasterPartitionTracker listens invokes from both JM and
> ShuffleMaster.
> # When JMPartitionTracker hears from JobMaster#disconnectTaskManager that a
> TM disconnects, it will check whether the disconnected tmID equals to a
> certain locationID of a partition. If so, tracking of the corresponding
> partition will be stopped.
> # When JobMasterPartitionTracker hears from ShuffleMaster that a data
> location gets lost, it will unregister corresponding partitions by locationID;
> *C. Partition Unregistration*
> When unregister a partition, JobMasterPartitionTracker removes the
> corresponding indexes to tmID and locationID firstly, and then release the
> partition by shuffle service types --
> # If the locationID equals to the tmID, it indicates the partition is
> accommodated by TM internal shuffle service, JMPartitionTracker will invokes
> TaskExecutorGateway for the release;
> # If the locationID doesn't equal to tmID, it indicates the partition is
> accommodated by external shuffle service, JMPartitionTracker will invokes
> ShuffleMaster for the release;
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