1 files changed, 102 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/testing/parallelization.rb b/activesupport/lib/active_support/testing/parallelization.rb
new file mode 100644
index 0000000000..59c8486f41
--- /dev/null
+++ b/activesupport/lib/active_support/testing/parallelization.rb
@@ -0,0 +1,102 @@
+# frozen_string_literal: true
+
+require "drb"
+require "drb/unix"
+
+module ActiveSupport
+  module Testing
+    class Parallelization # :nodoc:
+      class Server
+        include DRb::DRbUndumped
+
+        def initialize
+          @queue = Queue.new
+        end
+
+        def record(reporter, result)
+          reporter.synchronize do
+            reporter.record(result)
+          end
+        end
+
+        def <<(o)
+          @queue << o
+        end
+
+        def pop; @queue.pop; end
+      end
+
+      @after_fork_hooks = []
+
+      def self.after_fork_hook(&blk)
+        @after_fork_hooks << blk
+      end
+
+      def self.after_fork_hooks
+        @after_fork_hooks
+      end
+
+      @run_cleanup_hooks = []
+
+      def self.run_cleanup_hook(&blk)
+        @run_cleanup_hooks << blk
+      end
+
+      def self.run_cleanup_hooks
+        @run_cleanup_hooks
+      end
+
+      def initialize(queue_size)
+        @queue_size = queue_size
+        @queue      = Server.new
+        @pool       = []
+
+        @url = DRb.start_service("drbunix:", @queue).uri
+      end
+
+      def after_fork(worker)
+        self.class.after_fork_hooks.each do |cb|
+          cb.call(worker)
+        end
+      end
+
+      def run_cleanup(worker)
+        self.class.run_cleanup_hooks.each do |cb|
+          cb.call(worker)
+        end
+      end
+
+      def start
+        @pool = @queue_size.times.map do |worker|
+          fork do
+            DRb.stop_service
+
+            after_fork(worker)
+
+            queue = DRbObject.new_with_uri(@url)
+
+            while job = queue.pop
+              klass    = job[0]
+              method   = job[1]
+              reporter = job[2]
+              result   = Minitest.run_one_method(klass, method)
+
+              queue.record(reporter, result)
+            end
+
+            run_cleanup(worker)
+          end
+        end
+      end
+
+      def <<(work)
+        @queue << work
+      end
+
+      def shutdown
+        @queue_size.times { @queue << nil }
+        @pool.each { |pid| Process.waitpid pid }
+      end
+    end
+  end
+end