PostAlerter 作业最近卡住/OOM

[kris.kotlarek (Kris)]

我刚刚合并了另一个尝试改进此作业性能的请求：

FIX: more performance improvement for PostAlert job

我在几个实例上进行了测试，它们运行正常，但这些实例比你的要小。

如果此提交仍然导致失败，你能否提供 EXPLAIN ANALYSE 报告？生成它的脚本：

topic = Topic.last
user_option_sql_fragment =
  if SiteSetting.watched_precedence_over_muted
    <<~SQL
    INTERSECT
    SELECT user_id FROM user_options WHERE user_options.watched_precedence_over_muted IS false
    SQL
  else
    <<~SQL
    EXCEPT
    SELECT user_id FROM user_options WHERE user_options.watched_precedence_over_muted IS true
    SQL
  end
user_ids_sql = <<~SQL
  (
    SELECT user_id FROM category_users WHERE category_id = #{topic.category_id.to_i} AND notification_level = #{CategoryUser.notification_levels[:muted]}
    UNION
    SELECT user_id FROM tag_users tu JOIN topic_tags tt ON tt.tag_id = tu.tag_id AND tt.topic_id = #{topic.id} WHERE tu.notification_level = #{TagUser.notification_levels[:muted]}
    EXCEPT
    SELECT user_id FROM topic_users tus WHERE tus.topic_id = #{topic.id} AND tus.notification_level = #{TopicUser.notification_levels[:watching]}
  )
  #{user_option_sql_fragment}
SQL
sql = User.where("id IN (#{user_ids_sql})").to_sql

sql_with_index = <<~SQL
EXPLAIN ANALYZE #{sql};
SQL
result = ActiveRecord::Base.connection.execute("#{sql_with_index}")
puts sql_with_index
result.each do |r|
  puts r.values
end

这将帮助我找到缺失的索引或此查询的哪个部分如此缓慢。