zhuzhurk opened a new pull request #9860: [FLINK-14331][runtime] Reset vertices 
right after they transition to terminated states
URL: https://github.com/apache/flink/pull/9860
 
 
   
   ## What is the purpose of the change
   
   Currently in DefaultScheduler, tasks to restart will remain in terminated 
state until they are re-scheduled by the SchedulingStrategy.
   This behavior may cause 2 problems:
   1. Failed/Canceled tasks are possibly not be able to be restarted in lazy 
scheduling. e.g. The job A1-pipelined->B1 fails. And only A1 will be 
re-scheduled on restartTasks() since the inputs of B1 are not ready. B1 should 
be scheduled later on the partition consumable event from restarted A1. But the 
terminal state of B1 will prevent B1 from being scheduled.
   2. Keeping a task in FAILED/CANCELED state for a long time can happen if it 
takes a long time for its inputs to become ready again. This is also not 
friendly to users, which may cause confusions.
   
   This PR to reset vertices right after they transition to terminated states.
   
   
   ## Brief change log
   
     - *Change DefaultScheduler to reset vertex right after the vertex is 
terminated*
     - *Change DefaultScheduler to schedule vertices in CREATED state only*
     - *hotfix changes see each commits*
   
   
   ## Verifying this change
   
   
   This change is already covered by existing tests.
   
   This change also added some tests:
     - *Added UT to verify the changes on DefaultScheduler*
   
   ## 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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