add RAILS_MIN_THREADS, RAILS_MAX_THREADS, set default worker, preload if using workers

History.md

@@ -10,6 +10,11 @@
   * Changed #connected_port to #connected_ports (#2076)
   * `--control` has been removed. Use `--control-url` (#1487)
   * `worker_directory` has been removed. Use `directory`
+  * min_threads now set by environment variables RAILS_MIN_THREADS and MIN_THREADS
+  * max_threads now set by environment variables RAILS_MAX_THREADS and MAX_THREADS
+  * max_threads default to 5 in MRI or 16 for all other interpretters
+  * preload by default if workers > 1 and interpretter supports workers
+
 
 * Bugfixes
   * Windows update extconf.rb for use with ssp and varied Ruby/MSYS2 combinations (#2069)

lib/puma/configuration.rb

@@ -137,6 +137,8 @@ module Puma
       @file_dsl    = DSL.new(@options.file_options, self)
       @default_dsl = DSL.new(@options.default_options, self)
 
+      default_options[:preload_app] = (default_options[:workers] > 1 && Puma::Plugin.new.workers_supported?)
+
       if block
         configure(&block)
       end
@@ -167,14 +169,19 @@ module Puma
       self
     end
 
+    def default_max_threads
+      return 5 if Puma.mri?
+      16
+    end
+
     def puma_default_options
       {
-        :min_threads => 0,
-        :max_threads => 16,
+        :min_threads => Integer(ENV['RAILS_MIN_THREADS'] || ENV['MIN_THREADS'] || 0),
+        :max_threads => Integer(ENV['RAILS_MAX_THREADS'] || ENV['MAX_THREADS'] || default_max_threads),
         :log_requests => false,
         :debug => false,
         :binds => ["tcp://#{DefaultTCPHost}:#{DefaultTCPPort}"],
-        :workers => 0,
+        :workers => Integer(ENV['WEB_CONCURRENCY'] || 0),
         :daemon => false,
         :mode => :http,
         :worker_timeout => DefaultWorkerTimeout,

lib/puma/detect.rb

@@ -12,4 +12,8 @@ module Puma
   def self.windows?
     IS_WINDOWS
   end
+
+  def self.mri?
+    RUBY_ENGINE == 'ruby' || RUBY_ENGINE.nil? 
+  end
 end

test/test_config.rb

@@ -8,6 +8,58 @@ require "puma/configuration"
 class TestConfigFile < TestConfigFileBase
   parallelize_me!
 
+  def test_default_max_threads
+    max_threads = 16
+    max_threads = 5 if RUBY_ENGINE.nil? || RUBY_ENGINE == 'ruby'
+    assert_equal max_threads, Puma::Configuration.new.default_max_threads
+  end
+
+  def test_config_loads_correct_min_threads
+    conf = Puma::Configuration.new
+    assert_equal 0, conf.options.default_options[:min_threads]
+
+    ENV['MIN_THREADS'] = '7'
+    conf = Puma::Configuration.new
+    assert_equal 7, conf.options.default_options[:min_threads]
+
+    ENV['RAILS_MIN_THREADS'] = '8'
+    conf = Puma::Configuration.new
+    assert_equal 8, conf.options.default_options[:min_threads]
+  end
+
+  def test_config_loads_correct_max_threads
+    conf = Puma::Configuration.new
+    assert_equal conf.default_max_threads, conf.options.default_options[:max_threads]
+
+    ENV['MAX_THREADS'] = '7'
+    conf = Puma::Configuration.new
+    assert_equal 7, conf.options.default_options[:max_threads]
+
+    ENV['RAILS_MAX_THREADS'] = '8'
+    conf = Puma::Configuration.new
+    assert_equal 8, conf.options.default_options[:max_threads]
+  end
+
+  def test_config_loads_correct_workers
+    conf = Puma::Configuration.new
+    assert_equal 0, conf.options.default_options[:workers]
+
+    ENV['WEB_CONCURRENCY'] = '8'
+    conf = Puma::Configuration.new
+    assert_equal 8, conf.options.default_options[:workers]
+  end
+
+  def test_config_preloads_app_if_using_workers
+    ENV['WEB_CONCURRENCY'] = '0'
+    conf = Puma::Configuration.new
+    assert_equal false, conf.options.default_options[:preload_app]
+
+    ENV['WEB_CONCURRENCY'] = '2'
+    preload = Puma::Plugin.new.workers_supported?
+    conf = Puma::Configuration.new
+    assert_equal preload, conf.options.default_options[:preload_app]
+  end
+
   def test_app_from_rackup
     conf = Puma::Configuration.new do |c|
       c.rackup "test/rackup/hello-bind.ru"