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Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

Currently, the Flink cluster only requests Task Managers (TMs) when there is a resource requirement, and idle TMs are released after a certain period of time. However, in certain scenarios, we need to improve the efficiency of job execution by maintaining a certain number of available resources in the system. For example:

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Option nameDefault Value
slotmanager.number-of-slots.min0
slotmanager.min-total-resource.cpuno default value, it can be derived from slotmanager.number-of-slots.min
slotmanager.min-total-resource.memoryno default value, it can be derived from slotmanager.number-of-slots.min

Proposed Changes

Minimum required resource check in DefaultResourceAllocationStrategy

The minimum resource limitation will be implemented in the DefaultResourceAllocationStrategy of FineGrainedSlotManager.

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Notice: The minimum resource limitation will be fulfilled in the best effort manner. The unfulfilled request will be retried in the next resource check but will not block job scheduling.

Resource stability check in SlotManagerConfiguration

After minimum required resource options are introduced, users can configure both minimum and maximum required resources in SlotManager, which might lead to worker resource oscillation. Here is an example:

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To avoid this oscillation, we need to check the worker number derived from minimum and maximum resource configuration is consistent before starting SlotManager.


Compatibility, Deprecation, and Migration Plan

  • What impact (if any) will there be on existing users?  No

Test Plan

UT & Manually verify that the min resource limitation is working as expected.

Rejected Alternatives

If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.