Calls to graph_post_search_get have exceeded the rate of 10000 calls per 1 seconds. [HTTP 400]

Code

app_id   = "XXX";
app_secret = "YYY";

@oauth = Koala::Facebook::OAuth.new(app_id, app_secret)
app_oauth_token = @oauth.get_app_access_token

graph = Koala::Facebook::API.new(app_oauth_token)

while(true) do

  tags = Tag.current_broadcasting

  all_posts = graph.batch do |batch_api|
    tags.each do |tag|
      batch_api.search(tag, {:type => 'post', :since => since, :until => 'now'})
    end
  end

  all_posts.each do |posts|
    posts.each do |post|
      ...
    end
  end

  sleep 10

end 

Error trace

$ RAILS_ENV=production ruby lib/daemons/facebook_tracker.rb 
/home/rails/projectname/shared/bundle/ruby/1.9.1/gems/koala-1.7.0rc1/lib/koala/api/graph_api.rb:500:in  block in graph_call': type: OAuthException, code: 613, message: (#613) Calls to graph_post_search_get have exceeded the rate of 10000 calls per 1 seconds. [HTTP 400] (Koala::Facebook::ClientError)
    from /home/rails/projectname/shared/bundle/ruby/1.9.1/gems/koala-1.7.0rc1/lib/koala/api.rb:62:in  api'
    from /home/rails/projectname/shared/bundle/ruby/1.9.1/gems/koala-1.7.0rc1/lib/koala/api/graph_api.rb:498:in graph_call'
    from /home/rails/projectname/shared/bundle/ruby/1.9.1/gems/koala-1.7.0rc1/lib/koala/api/graph_api.rb:313:in  search'
    from lib/daemons/facebook_tracker.rb:40:in block in <main>'
    from /home/rails/projectname/shared/bundle/ruby/1.9.1/gems/activerecord-3.2.14/lib/active_record/relation/delegation.rb:6:in  each'
    from /home/rails/projectname/shared/bundle/ruby/1.9.1/gems/activerecord-3.2.14/lib/active_record/relation/delegation.rb:6:in each'
    from lib/daemons/facebook_tracker.rb:38:in  <main>'