Errno::EMFILE（打开的文件过多 - 套接字（2））在乘客中运行时使用 RedisStore 进行缓存

Question

我的应用程序正在使用 redis 存储，它在本地运行良好，但在生产中，使用 Phusion Passenger（开源）我遇到了这个错误。

Errno::EMFILE (Too many open files - socket(2)):
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:24:in `initialize'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:24:in `initialize'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:143:in `new'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:143:in `connect_addrinfo'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:187:in `block in connect'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:185:in `each'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:185:in `each_with_index'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:185:in `connect'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/connection/ruby.rb:260:in `connect'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:336:in `establish_connection'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:101:in `block in connect'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:293:in `with_reconnect'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:100:in `connect'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:364:in `ensure_connected'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:221:in `block in process'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:306:in `logging'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:220:in `process'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis/client.rb:120:in `call'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis.rb:862:in `block in get'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis.rb:58:in `block in synchronize'
/usr/local/rvm/rubies/ruby-2.2.2/lib/ruby/2.2.0/monitor.rb:211:in `mon_synchronize'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis.rb:58:in `synchronize'
vendor/bundle/ruby/2.2.0/gems/redis-3.3.0/lib/redis.rb:861:in `get'
vendor/bundle/ruby/2.2.0/gems/redis-store-1.1.7/lib/redis/store/interface.rb:5:in `get'
vendor/bundle/ruby/2.2.0/gems/redis-store-1.1.7/lib/redis/store/marshalling.rb:17:in `get'
vendor/bundle/ruby/2.2.0/gems/redis-activesupport-4.1.5/lib/active_support/cache/redis_store.rb:230:in `block in read_entry'
vendor/bundle/ruby/2.2.0/gems/redis-activesupport-4.1.5/lib/active_support/cache/redis_store.rb:212:in `call'
vendor/bundle/ruby/2.2.0/gems/redis-activesupport-4.1.5/lib/active_support/cache/redis_store.rb:212:in `with'
vendor/bundle/ruby/2.2.0/gems/redis-activesupport-4.1.5/lib/active_support/cache/redis_store.rb:230:in `read_entry'
vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/cache.rb:413:in `block in exist?'
vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/cache.rb:547:in `block in instrument'
vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/notifications.rb:166:in `instrument'
vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/cache.rb:547:in `instrument'
vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.6/lib/active_support/cache.rb:412:in `exist?'
vendor/bundle/ruby/2.2.0/gems/redis-activesupport-4.1.5/lib/active_support/cache/redis_store.rb:200:in `exist?'

我的缓存初始化代码是

Rails.application.configure do
    Rack::MiniProfiler.config.storage_options = { host: 'redis.local.com', port: 6379 }
    Rack::MiniProfiler.config.storage = Rack::MiniProfiler::RedisStore
    config.cache_store = :redis_store, http://redis.local.com:6379, { expires_in: 5.minutes }
    Rails.cache = ActiveSupport::Cache::RedisStore.new
end

在 redis-rb 和 redis-store gems 中搜索过，根本没有发现任何东西。 如何确保乘客在将其用作缓存存储时不会创建与 Redis 的多个连接？

Answer 1

这不是乘客问题。这是您的应用程序达到其文件描述符限制。为什么会达到极限？不知道——也许它应该打开很多文件描述符，或者你可能在某处泄漏文件描述符。您可以尝试的一件事是增加passenger_app_file_descriptor_ulimit，但这只有在您的应用程序确实应该使用许多文件描述符而不是泄漏它们时才有帮助。如果您的应用泄漏了它们，那么剩下的唯一事情就是调试您的应用，找出泄漏的来源。