sidekiq-unique-jobs gem not deleting expired keys in its uniquejobs hash

sidekiq_unique_jobs_hash_compactor.rb

# https://github.com/mhenrixon/sidekiq-unique-jobs/issues/161
# Even worse: https://github.com/mhenrixon/sidekiq-unique-jobs/issues/234
class SidekiqUniqueJobsHashCompactor
  include Sidekiq::Worker
  sidekiq_options queue: "slow"

  def perform
    # Skip if there are jobs queued...
    return unless Sidekiq::Queue.all.select { |q| q.size > 100 }.blank?

    # We need this to get a redis, db12 with no namespace gem
    redis = Redis.new(host: $redis.client.host, port: $redis.client.port, db: 12, thread_safe: true)

    to_be_deleted = []

    offset_str = redis.get("uniquejobscursor")
    offset = offset_str.try(:to_i) || 0

    cursor, jobs = redis.hscan("uniquejobs", offset, count: 2_000)

    redis.set("uniquejobscursor", cursor)
    jobs.each do |job_array|
      jid, unique_key = job_array
      next if redis.get(unique_key)
      to_be_deleted << jid
    end
    to_be_deleted.blank? ? num_del = 0 : num_del = redis.hdel("uniquejobs", to_be_deleted)
    FDStats.count('uniquejobs_hash_compactor', num_del)
  end
end

# start = Time.now; SidekiqUniqueJobsHashCompactor.new.perform; puts "#{(Time.now - start) * 1000} milliseconds"