Elastic Beanstalk數據庫池問題

Question

我最近決定從Heroku切換到通過他們的Elastic Beanstalk服務直接部署到AWS - 希望我的術語仍然適合AWS。我有在EB上運行的應用程序和Heroku上的應用程序（這是一個免費的Heroku應用程序，因此可能需要10秒鐘才能啓動）。該應用程序在Heroku上運行完美，但在EB上它只是有時會加載。也許像4次中的1次，我得到一個Internal Server Error。我的數據庫池設置爲5，如果我擴展到25它可以工作，但我是唯一使用該網站的人，從我聽到的5應該是充足的。

這裏是我的database.yml：

development: 
    adapter: sqlite3 
    database: db/website.db 
    pool: 5 
    timeout: 5000 
test: 
    adapter: sqlite3 
    database: db/cucumber-tests.db 
    pool: 5 
    timeout: 5000 
production: 
    adapter: postgresql 
    encoding: utf8 
    database: <%= ENV['RDS_DB_NAME'] %> 
    username: <%= ENV['RDS_USERNAME'] %> 
    password: <%= ENV['RDS_PASSWORD'] %> 
    pool: 5 
    host: <%= ENV['RDS_HOSTNAME'] %> 
    port: <%= ENV['RDS_PORT'] %> 

側面說明，以後我弄清楚爲什麼池5是不夠的，如何讓我的池大小可擴展性？從我可以告訴的是沒有RDS_POOL變量。有沒有一種方法可以根據用戶數量進行縮放？

這裏是彪馬我的錯誤日誌：

------------------------------------- 
/var/log/puma/puma.log 
------------------------------------- 
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/xss_header.rb:18:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/path_traversal.rb:16:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/json_csrf.rb:18:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/frame_options.rb:31:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/session/abstract/id.rb:225:in `context' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/session/abstract/id.rb:220:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/nulllogger.rb:9:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/head.rb:13:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:182:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:2013:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1487:in `block in call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1787:in `synchronize' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1487:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/deflater.rb:35:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/configuration.rb:232:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/server.rb:578:in `handle_request' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/server.rb:415:in `process_client' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/server.rb:275:in `block in run' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/thread_pool.rb:120:in `block in spawn_thread' 
2017-03-10 03:43:14 - ActiveRecord::ConnectionTimeoutError - could not obtain a connection from the pool within 5.000 seconds (waited 5.000 seconds); all pooled connections were i 
n use: 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:202:in `block in wait_poll' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:193:in `loop' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:193:in `wait_poll' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:154:in `internal_poll' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:278:in `internal_poll' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:148:in `block in poll' 
     /opt/rubies/ruby-2.3.1/lib/ruby/2.3.0/monitor.rb:214:in `mon_synchronize' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:158:in `synchronize' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:148:in `poll' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:717:in `acquire_connection' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:490:in `checkout' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:364:in `connection' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_adapters/abstract/connection_pool.rb:883:in `retrieve_connection' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_handling.rb:128:in `retrieve_connection' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/connection_handling.rb:91:in `connection' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/associations/join_dependency.rb:96:in `initialize' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/relation/finder_methods.rb:399:in `new' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/relation/finder_methods.rb:399:in `construct_join_dependency' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/relation/finder_methods.rb:321:in `exists?' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.2/lib/active_record/querying.rb:3:in `exists?' 
     app/views/index.erb:66:in `block in singleton class' 
app/views/index.erb:-6:in `instance_eval' 
     app/views/index.erb:-6:in `singleton class' 
     app/views/index.erb:-8:in `__tilt_47116404404940' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/tilt-2.0.6/lib/tilt/template.rb:161:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/tilt-2.0.6/lib/tilt/template.rb:161:in `evaluate' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/tilt-2.0.6/lib/tilt/template.rb:100:in `render' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:823:in `render' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:667:in `erb' 
     /var/app/current/app/controllers/application_controller.rb:60:in `block in <class:ApplicationController>' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1611:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1611:in `block in compile!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:975:in `block (3 levels) in route!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:994:in `route_eval' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:975:in `block (2 levels) in route!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1015:in `block in process_route' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1013:in `catch' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1013:in `process_route' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:973:in `block in route!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:972:in `each' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:972:in `route!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1085:in `block in dispatch!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1067:in `block in invoke' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1067:in `catch' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1067:in `invoke' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1082:in `dispatch!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:907:in `block in call!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1067:in `block in invoke' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1067:in `catch' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1067:in `invoke' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:907:in `call!' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:895:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/xss_header.rb:18:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/path_traversal.rb:16:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/json_csrf.rb:18:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/base.rb:49:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-protection-1.5.3/lib/rack/protection/frame_options.rb:31:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/session/abstract/id.rb:225:in `context' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/session/abstract/id.rb:220:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/nulllogger.rb:9:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/head.rb:13:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:182:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:2013:in `call' 
/opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1487:in `block in call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1787:in `synchronize' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/sinatra-1.4.8/lib/sinatra/base.rb:1487:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/rack-1.6.5/lib/rack/deflater.rb:35:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/configuration.rb:232:in `call' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/server.rb:578:in `handle_request' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/server.rb:415:in `process_client' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/server.rb:275:in `block in run' 
     /opt/rubies/ruby-2.3.1/lib/ruby/gems/2.3.0/gems/puma-3.7.1/lib/puma/thread_pool.rb:120:in `block in spawn_thread' 

- 所有的代碼是開源的，可以發現here -

謝謝。任何幫助深表感謝。

更新：我不能讓這個應用程序停機。我現在將游泳池設置爲25。我也改變了DSN所以old app can be found here和the new app here

更新2：我加入ruby-on-rails標記，因爲這個問題涉及到獲得更多的牽引力，但該項目是利用西納特拉不是Rails的。

Answer 1

它看起來像你正在使用彪馬一個線程的Web服務器。 Puma在一個進程中啓動多個ruby線程來同時處理請求。 Puma創建的線程數可能會高於您池中的數據庫連接數（在database.yml中定義）。

ActiveRecord自然保持打開一個數據庫連接池並懶惰地創建新的連接。您的database.yml看起來好像您的最大池大小已設置爲5.這意味着ActiveRecord不會在池中創建超過5個連接，並且只會在池爲空且需要連接時創建新連接。

我無法在您的存儲庫中找到puma配置，因此我會假設puma使用默認設置。 The default max threads for Puma is 16。這可能表示您的Web服務器有16個線程正在運行（最糟糕的情況），並且第5個線程之後的每個線程都在等待連接返回到要使用的池。這是你的16個線程共享的5個連接。作爲最佳做法，我總是確保數據庫池大小爲n+1，其中n是將在我的應用程序中運行的最大線程數。

我猜不出爲什麼這個問題在heroku中不存在。