Change automatic post deletion thresholds and load detection (#24614)

app/workers/scheduler/accounts_statuses_cleanup_scheduler.rb

@@ -7,28 +7,30 @@ class Scheduler::AccountsStatusesCleanupScheduler
   # This limit is mostly to be nice to the fediverse at large and not
   # generate too much traffic.
   # This also helps limiting the running time of the scheduler itself.
-  MAX_BUDGET         = 150
+  MAX_BUDGET         = 300
 
-  # This is an attempt to spread the load across instances, as various
-  # accounts are likely to have various followers.
+  # This is an attempt to spread the load across remote servers, as
+  # spreading deletions across diverse accounts is likely to spread
+  # the deletion across diverse followers. It also helps each individual
+  # user see some effect sooner.
   PER_ACCOUNT_BUDGET = 5
 
   # This is an attempt to limit the workload generated by status removal
-  # jobs to something the particular instance can handle.
-  PER_THREAD_BUDGET  = 6
+  # jobs to something the particular server can handle.
+  PER_THREAD_BUDGET  = 5
 
-  # Those avoid loading an instance that is already under load
-  MAX_DEFAULT_SIZE    = 200
-  MAX_DEFAULT_LATENCY = 5
-  MAX_PUSH_SIZE       = 500
-  MAX_PUSH_LATENCY    = 10
-
-  # 'pull' queue has lower priority jobs, and it's unlikely that pushing
-  # deletes would cause much issues with this queue if it didn't cause issues
-  # with default and push. Yet, do not enqueue deletes if the instance is
-  # lagging behind too much.
-  MAX_PULL_SIZE       = 10_000
-  MAX_PULL_LATENCY    = 5.minutes.to_i
+  # These are latency limits on various queues above which a server is
+  # considered to be under load, causing the auto-deletion to be entirely
+  # skipped for that run.
+  LOAD_LATENCY_THRESHOLDS = {
+    default: 5,
+    push: 10,
+    # The `pull` queue has lower priority jobs, and it's unlikely that
+    # pushing deletes would cause much issues with this queue if it didn't
+    # cause issues with `default` and `push`. Yet, do not enqueue deletes
+    # if the instance is lagging behind too much.
+    pull: 5.minutes.to_i,
+  }.freeze
 
   sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
@@ -61,19 +63,20 @@ class Scheduler::AccountsStatusesCleanupScheduler
   end
 
   def compute_budget
-    threads = Sidekiq::ProcessSet.new.select { |x| x['queues'].include?('push') }.map { |x| x['concurrency'] }.sum
+    # Each post deletion is a `RemovalWorker` job (on `default` queue), each
+    # potentially spawning many `ActivityPub::DeliveryWorker` jobs (on the `push` queue).
+    threads = Sidekiq::ProcessSet.new.select { |x| x['queues'].include?('push') }.pluck('concurrency').sum
     [PER_THREAD_BUDGET * threads, MAX_BUDGET].min
   end
 
   def under_load?
-    queue_under_load?('default', MAX_DEFAULT_SIZE, MAX_DEFAULT_LATENCY) || queue_under_load?('push', MAX_PUSH_SIZE, MAX_PUSH_LATENCY) || queue_under_load?('pull', MAX_PULL_SIZE, MAX_PULL_LATENCY)
+    LOAD_LATENCY_THRESHOLDS.any? { |queue, max_latency| queue_under_load?(queue, max_latency) }
   end
 
   private
 
-  def queue_under_load?(name, max_size, max_latency)
-    queue = Sidekiq::Queue.new(name)
-    queue.size > max_size || queue.latency > max_latency
+  def queue_under_load?(name, max_latency)
+    Sidekiq::Queue.new(name).latency > max_latency
   end
 
   def last_processed_id