[GitHub] [flink] zhuzhurk opened a new pull request #9288: [FLINK-13421] [runtime] Make MultiTaskSlot not available for allocation when it’s releasing c…

[GitBox <gi...@apache.org>]

zhuzhurk opened a new pull request #9288: [FLINK-13421] [runtime] Make MultiTaskSlot not available for allocation when it’s releasing c…
URL: https://github.com/apache/flink/pull/9288
 
 
   …hildren to avoid ConcurrentModificationException
   
   ## What is the purpose of the change
   
   *ConcurrentModificationException happened in the children release loop in MultiTaskSlot#release.*
   
   *It happened because new slot allocations happened, adding a new child to the MultiTaskSlot, thus modified the children field.*
   
   *New slot allocations happened because a task failover is caused by a child slot's payload releasing. The failover canceled tasks and returned allocated slots to SlotPool. The returned allocated slots were assigned to some tasks that were not canceled yet. The slot assignment satisfies the input location preference constraints of some downstream tasks, and triggered the slot allocation of these tasks.*
   
   *To fix this, this PR changes MultiTaskSlot to be not available for slot allocation when it is in releasingChildren state. The change is in SlotSharingManager#listResolvedRootSlotInfo.(SlotSharingManager#getUnresolvedRootSlot is not necessary for a change as unresolved multi-task slot is simple and does not lead to a slot allocation.) *
   
   
   ## Brief change log
   
   *(for example:)*
     - *in SlotSharingManager#listResolvedRootSlotInfo*
   
   ## Verifying this change
   
   This change added tests and can be verified as follows:
   
     - *Added uint test SlotSharingManagerTest#testResolvedSlotInReleasingIsNotAvailable*
   
   ## Does this pull request potentially affect one of the following parts:
   
     - Dependencies (does it add or upgrade a dependency): (yes / **no**)
     - The public API, i.e., is any changed class annotated with `@Public(Evolving)`: (yes / **no**)
     - The serializers: (yes / **no** / don't know)
     - The runtime per-record code paths (performance sensitive): (yes / **no** / don't know)
     - Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (**yes** / no / don't know)
     - The S3 file system connector: (yes / **no** / don't know)
   
   ## Documentation
   
     - Does this pull request introduce a new feature? (yes / **no**)
     - If yes, how is the feature documented? (not applicable / docs / JavaDocs / **not documented**)
   

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