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Yi Pan (Data Infrastructure) commented on SAMZA-906: ---------------------------------------------------- Thanks! Merged and committed. > Host Affinity - Minimize task reassignment when container count changes > ----------------------------------------------------------------------- > > Key: SAMZA-906 > URL: https://issues.apache.org/jira/browse/SAMZA-906 > Project: Samza > Issue Type: Bug > Reporter: Jake Maes > Assignee: Jake Maes > Fix For: 0.10.1 > > Attachments: SAMZA-906.patch, SAMZA-906_2.patch, SAMZA-906_3.patch, > SAMZA-906_3.patch, SAMZA-906_4.patch, SAMZA-906_5.patch > > > When the job container count changes the default taskname grouper > (GroupByContainerCount) will reassign all the tasks among the new container > list in a round-robin fashion. This causes many of the tasks to shift to new > containers. The shifted tasks will be unable to restore state from local disk > because the new containers may not be assigned to the same host that the > task's original container was assigned to. > This ticket is to implement a task-to-container affinity, which complements > the container-to-host affinity in the current implementation. The > implementation will include a mapping which is persisted to the coordinator > stream and is used as the basis for the new task-to-container mapping > (ContainerModel). > If the container count doesn't change, the old task mapping will be used. > (Note that this will allow tools to inject custom mappings by writing to the > coordinator stream). > If the container count changes, a minimal number of tasks will be reassigned > from the persisted mapping, in order to "balance" the containers. -- This message was sent by Atlassian JIRA (v6.3.4#6332)