如何让Rails.cache(内存缓存)与Puma一起使用？

Question

我正在使用Rails 5.1.我在Rails中发生了应用程序范围的memory_store缓存.这是在我的config/environments/development.rb文件中设置的

  £ Enable/disable caching. By default caching is disabled.
  if Rails.root.join('tmp/caching-dev.txt').exist?
    config.action_controller.perform_caching = true

    config.cache_store = :memory_store
    config.public_file_server.headers = {
      'Cache-Control' => 'public, max-age=172800'
    }
  else
    config.action_controller.perform_caching = true
    config.cache_store = :memory_store
  end

这让我可以做的事情

      Rails.cache.fetch(cache_key) do
        msg_data
      end

在我的应用程序的一部分(Web套接字)并访问我的应用程序的另一部分(控制器)中的数据.但是,我注意到的是,如果我用puma运行启动我的Rails服务器(例如在config/puma.rb中包含以下文件)...

threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }.to_i
threads threads_count, threads_count

£ Specifies the `port` that Puma will listen on to receive requests, default is 3000.
£
port        ENV.fetch("PORT") { 3000 }

£ Specifies the number of `workers` to boot in clustered mode.
£ Workers are forked webserver processes. If using threads and workers together
£ the concurrency of the application would be max `threads` * `workers`.
£ Workers do not work on JRuby or Windows (both of which do not support
£ processes).
£
workers ENV.fetch("WEB_CONCURRENCY") { 4 }

app_dir = File.expand_path("../..", __FILE__)
shared_dir = "£{app_dir}/shared"

£ Default to production
rails_env = ENV['RAILS_ENV'] || "production"
environment rails_env

£ Set up socket location
bind "unix://£{shared_dir}/sockets/puma.sock"

£ Logging
stdout_redirect "£{shared_dir}/log/puma.stdout.log", "£{shared_dir}/log/puma.stderr.log", true

£ Set master PID and state locations
pidfile "£{shared_dir}/pids/puma.pid"
state_path "£{shared_dir}/pids/puma.state"
activate_control_app





£ Use the `preload_app!` method when specifying a `workers` number.
£ This directive tells Puma to first boot the application and load code
£ before forking the application. This takes advantage of Copy On Write
£ process behavior so workers use less memory. If you use this option
£ you need to make sure to reconnect any threads in the `on_worker_boot`
£ block.
£
£ preload_app!

£ The code in the `on_worker_boot` will be called if you are using
£ clustered mode by specifying a number of `workers`. After each worker
£ process is booted this block will be run, if you are using `preload_app!`
£ option you will want to use this block to reconnect to any threads
£ or connections that may have been created at application boot, Ruby
£ cannot share connections between processes.
£
on_worker_boot do
  require "active_record"
  ActiveRecord::Base.connection.disconnect! rescue ActiveRecord::ConnectionNotEstablished
  ActiveRecord::Base.establish_connection(YAML.load_file("£{app_dir}/config/database.yml")[rails_env])
end

£ Allow puma to be restarted by `rails restart` command.
plugin :tmp_restart

内存缓存不再有效.换一种说法

Rails.cache.fetch(cache_key)

永远不会回报.我想有一个多线程的puma环境(最终)优雅地处理许多请求.但是我也喜欢我的缓存工作.我怎样才能让他们一起玩？

Answer 1

您不能memory_store与以集群模式运行的 puma 一起使用（即使用多个工作器）。在 Rails 指南中就是这么说的。你不能在不同的进程之间共享内存，所以这显然是有道理的。

如果将 puma worker 减少到 1 个不是一种选择，那么请考虑使用 Redis 或 Memcached。Rails的指南中的文档在这方面是相当完整的-你需要一个宝石或两个添加到您Gemfile，并更新config.cache_store。您需要在盒子上安装相关服务，或者有很多托管服务提供商会为您管理它（Heroku Redis、Redis To Go、Memcachier 等）