Tasks

• v0.20
  • Design: 📖 Add a design for a priority queue #3013
  • Initial implementation: ✨ Add a priority queue #3014
  • 🐛 Bugfixes for priority queue #3060
  • 🐛 Fix a bug in the priorityqueue metrics #3066
• v0.21
  • 🌱 Add priority label to PQ depth metric #3156
  • 🐛Fix behavior of rate limit option in priorityqueue.AddWithOpts #3103
  • 🌱 Add debug logging for the state of the priority queue #3075
  • ✨ Leverage isInInitialList of ResourceEventHandler.OnAdd, Add IsInInitialList to TypedCreateEvent #3162
  • 🌱 Remove redundant WithLowPriorityWhenUnchanged in builder #3168
  • ✨ Controller: Retain the priority #3167
  • 🐛Implement priorityqueue as default on handlers if using priorityqueue interface #3111
  • 🌱 Handlers: Use low priority when object is unchanged and priority queue #3152
  • 🌱 Followups to default low priority in mappers #3160
  • 🌱 TypedEnqueueRequestForOwner: Decrease priority when unchanged #3174
• v0.22
  • ⚠️ Priorityqueue: Make priority opt a pointer #3289
  • ✨ WithLowPriorityWhenUnchanged: Set Priority for all add methods  #3290
  • 🐛 Priorityqueue: Shutdown on shutdown #3250
  • 🐛 Priorityqueue: Don't block on Get when queue is shutdown #3243
  • [release-0.22] 🐛 priority queue: properly sync the waiter manipulation  #3371
• v0.23 (enabled per default)
  • 🐛 Don't block on Get when queue is shutdown (2nd try) #3337
  • ✨ Add optional Priority field to reconcile.Result #3333
  • ✨ Priorityqueue: Enable per default #3332
  • 🐛 Fix a bug where the priorityqueue would sometimes not return high-priority items first #3330
  • 🌱 Prioriyqueue tests: Add and use newQueueWithTimeForwarder #3336
  • 🌱 Priorityqueue tests: Use synctest #3350
  • 🐛 priority queue: properly sync the waiter manipulation #3368
  • 🌱 Add some more tests to the priorityqueue #3387
  • ✨ Fix unused priorityqueue test: TestWhenAddingMultipleItemsWithRatelimitTrueTheyDontAffectEachOther #3395
  • 🐛 Priorityqueue: Do FIFO ordering within priorities and not across #3408
  • ✨ Use a buffer to optimize priority queue AddWithOpts performance #3415
  • 🌱 Priorityqueue: Use separate b-trees for ready and non-ready items #3416
  • 🐛 Limit depthWithPriorityMetric cardinality to 25 #3419

Ideas:

• Add Priority parameter to reconcile.Request (xref: 📖 Add a design for a priority queue #3013 (comment))
  • Won't implement until we have a clear use case for it

Feature enablement

The feature can be enabled by setting the UsePriorityQueue option to true, e.g.:

	ctrlOptions := ctrl.Options{
		Controller: config.Controller{
			UsePriorityQueue: ptr.To[bool](true),
		},
        ...
	}

	mgr, err := ctrl.NewManager(restConfig, ctrlOptions)

Original issue description

While discussing #857 (comment) an idea come up about having something like a priority queue, so we can give resync events a lower priority while assigning to other events a higher priority.

This could help when there are many objects of the same type and at every resync period there is a storm of events being added to the queue.

cc @alvaroaleman @sbueringer