Reduce number of items in feeds, optimize regeneration worker slightly,

make regeneration worker unique, (only schedule/execute once at a time)

app/lib/feed_manager.rb

@@ -5,7 +5,7 @@ require 'singleton'
 class FeedManager
   include Singleton
 
-  MAX_ITEMS = 800
+  MAX_ITEMS = 400
 
   def key(type, id)
     "feed:#{type}:#{id}"
@@ -50,9 +50,9 @@ class FeedManager
 
   def merge_into_timeline(from_account, into_account)
     timeline_key = key(:home, into_account.id)
-    query        = from_account.statuses.limit(MAX_ITEMS)
+    query        = from_account.statuses.limit(FeedManager::MAX_ITEMS / 4)
 
-    if redis.zcard(timeline_key) >= FeedManager::MAX_ITEMS
+    if redis.zcard(timeline_key) >= FeedManager::MAX_ITEMS / 4
       oldest_home_score = redis.zrange(timeline_key, 0, 0, with_scores: true)&.first&.last&.to_i || 0
       query = query.where('id > ?', oldest_home_score)
     end

app/services/precompute_feed_service.rb

@@ -5,9 +5,11 @@ class PrecomputeFeedService < BaseService
   # @param [Symbol] type :home or :mentions
   # @param [Account] account
   def call(_, account)
-    Status.as_home_timeline(account).limit(FeedManager::MAX_ITEMS).each do |status|
-      next if status.direct_visibility? || FeedManager.instance.filter?(:home, status, account)
-      redis.zadd(FeedManager.instance.key(:home, account.id), status.id, status.reblog? ? status.reblog_of_id : status.id)
+    redis.pipelined do
+      Status.as_home_timeline(account).limit(FeedManager::MAX_ITEMS / 4).each do |status|
+        next if status.direct_visibility? || FeedManager.instance.filter?(:home, status, account)
+        redis.zadd(FeedManager.instance.key(:home, account.id), status.id, status.reblog? ? status.reblog_of_id : status.id)
+      end
     end
   end
 

app/workers/regeneration_worker.rb

@@ -3,7 +3,7 @@
 class RegenerationWorker
   include Sidekiq::Worker
 
-  sidekiq_options queue: 'pull', backtrace: true
+  sidekiq_options queue: 'pull', backtrace: true, unique: :until_executed
 
   def perform(account_id, _ = :home)
     PrecomputeFeedService.new.call(:home, Account.find(account_id))