Merge remote-tracking branch 'origin/copy-puma-config-from-rails5' into registry-849

config/puma.rb

@@ -1,14 +1,56 @@
-preload_app!
+# Puma can serve each request in a thread from an internal thread pool.
+# The `threads` method setting takes two numbers: a minimum and maximum.
+# Any libraries that use thread pools should be configured to match
+# the maximum value specified for Puma. Default is set to 5 threads for minimum
+# and maximum; this matches the default thread size of Active Record.
+#
+threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }
+threads threads_count, threads_count
 
-threads 1, 4
-workers 2
+# Specifies the `port` that Puma will listen on to receive requests; default is 3000.
+#
+port        ENV.fetch("PORT") { 3000 }
 
-on_worker_boot do
-  ActiveSupport.on_load(:active_record) do
-    ActiveRecord::Base.establish_connection
-  end
-end
+# Specifies the `environment` that Puma will run in.
+#
+environment ENV.fetch("RAILS_ENV") { "development" }
 
-before_fork do
-  ActiveRecord::Base.connection_pool.disconnect!
-end
+# 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") { 2 }
+
+# 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!
+
+# If you are preloading your application and using Active Record, it's
+# recommended that you close any connections to the database before workers
+# are forked to prevent connection leakage.
+#
+# before_fork do
+#   ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
+# end
+
+# 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 the `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, as Ruby
+# cannot share connections between processes.
+#
+# on_worker_boot do
+#   ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
+# end
+#
+
+# Allow puma to be restarted by `rails restart` command.
+plugin :tmp_restart