[FLINK-4459] Introduce SlotProvider for Scheduler

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0
• Component/s: Runtime / Coordination
• Assignee: Kurt Young
• Reporter: Till Rohrmann
• Created: 23/Aug/16 17:45
• Updated: 28/Feb/19 14:32
• Resolved: 04/Sep/16 21:12

Description

Currently the Scheduler maintains a queue of available instances which it scans if it needs a new slot. If it finds a suitable instance (having free slots available) it will allocate a slot from it.

This slot allocation logic can be factored out and be made available via a SlotProvider interface. The SlotProvider has methods to allocate a slot given a set of location preferences. Slots should be returned as Futures, because in the future the slot allocation might happen asynchronously (Flip-6).

In the first version, the SlotProvider implementation will simply encapsulate the existing slot allocation logic extracted from the Scheduler. When a slot is requested it will return a completed or failed future since the allocation happens synchronously.

The refactoring will have the advantage to simplify the Scheduler class and to pave the way for upcoming refactorings (Flip-6).

Issue Links

• blocks: FLINK-4344 Implement new JobManager
• requires: FLINK-4361 Introduce Flink's own future abstraction
• links to: GitHub Pull Request #2424

Sub-Tasks

• Decouple Slot and Instance: Closed