example.rb

module A
  def init_ddb_client
    Aws::DynamoDB::Client.new
  end

  def query params
    client = init_ddb_client # Exception here
    # loop for counting
  end
end

class B
  include A # mixin module A
end

# in sidekiq worker
b = B.new
params = {
  # sth...
}
b.query(params)