From 6aee485882145a306e89446b30cedf254e85d9eb Mon Sep 17 00:00:00 2001
From: Michael Grosser <michael@grosser.it>
Date: Thu, 2 Apr 2026 18:09:15 -0700
Subject: [PATCH] ruby 4 ractors

---
 lib/parallel.rb       | 88 +++++++++++++++++++++++++++----------------
 spec/parallel_spec.rb |  4 +-
 2 files changed, 58 insertions(+), 34 deletions(-)

diff --git a/lib/parallel.rb b/lib/parallel.rb
index 491a85d..f8494d9 100644
--- a/lib/parallel.rb
+++ b/lib/parallel.rb
@@ -471,62 +471,86 @@ def work_in_ractors(job_factory, options)
         raise ArgumentError, "pass the code you want to execute as `ractor: [ClassName, :method_name]`"
       end
 
+      use_port = defined?(Ractor::Port)
+
       # build
-      ractors = Array.new(options.fetch(:count)) do
-        Ractor.new do
-          loop do
-            got = receive
-            (klass, method_name), item, index = got
-            break if index == :break
-            begin
-              Ractor.yield [nil, klass.send(method_name, item), item, index]
-            rescue StandardError => e
-              Ractor.yield [e, nil, item, index]
-            end
-          end
-        end
+      ports = {} # port (ruby 4+) or ractor (ruby 3) => ractor
+      options.fetch(:count).times do
+        port, ractor = ractor_build(use_port)
+        ports[port] = ractor
       end
 
       # start
-      ractors.dup.each do |ractor|
-        if (set = job_factory.next)
-          item, index = set
+      ports.dup.each do |port, ractor|
+        if (job = job_factory.next)
+          item, index = job
           instrument_start item, index, options
           ractor.send [callback, item, index]
-        else
-          ractor.send([[nil, nil], nil, :break]) # stop the ractor
-          ractors.delete ractor
+        else # not enough work, `receive` would hang
+          ractor_stop ractor
+          ports.delete port
         end
       end
 
-      # replace with new items
-      while (set = job_factory.next)
-        item_next, index_next = set
-        done, (exception, result, item, index) = Ractor.select(*ractors)
+      # receive result and send new items to done ractors
+      while (job = job_factory.next)
+        # receive result
+        done_port, (exception, result, item_prev, index_prev) = Ractor.select(*ports.keys)
+        done_ractor = ports[done_port]
         if exception
-          ractors.delete done
+          ports.delete done_port
           break
         end
-        instrument_finish item, index, result, options
-        results_mutex.synchronize { results[index] = (options[:preserve_results] == false ? nil : result) }
+        ractor_result item_prev, index_prev, result, results, results_mutex, options
 
+        # send new
+        item_next, index_next = job
         instrument_start item_next, index_next, options
-        done.send([callback, item_next, index_next])
+        done_ractor.send([callback, item_next, index_next])
       end
 
       # finish
-      ractors.each do |ractor|
-        (new_exception, result, item, index) = ractor.take
+      ports.each do |port, ractor|
+        (new_exception, result, item, index) = use_port ? port.receive : ractor.take
         exception ||= new_exception
         next if new_exception
-        instrument_finish item, index, result, options
-        results_mutex.synchronize { results[index] = (options[:preserve_results] == false ? nil : result) }
-        ractor.send([[nil, nil], nil, :break]) # stop the ractor
+        ractor_result item, index, result, results, results_mutex, options
+        ractor_stop ractor
       end
 
       exception || results
     end
 
+    def ractor_build(use_port)
+      args = use_port ? [Ractor::Port.new] : []
+      ractor = Ractor.new(*args) do |port|
+        loop do
+          (klass, method_name), item, index = receive
+          break if index == :break
+          begin
+            result = [nil, klass.send(method_name, item), item, index]
+          rescue StandardError => e
+            result = [e, nil, item, index]
+          end
+          if port
+            port.send result
+          else
+            Ractor.yield result
+          end
+        end
+      end
+      [use_port ? args.first : ractor, ractor]
+    end
+
+    def ractor_result(item, index, result, results, results_mutex, options)
+      instrument_finish item, index, result, options
+      results_mutex.synchronize { results[index] = (options[:preserve_results] == false ? nil : result) }
+    end
+
+    def ractor_stop(ractor)
+      ractor.send([[nil, nil], nil, :break])
+    end
+
     def work_in_processes(job_factory, options, &blk)
       workers = create_workers(job_factory, options, &blk)
       results = []
diff --git a/spec/parallel_spec.rb b/spec/parallel_spec.rb
index 6e4e208..d2093fa 100644
--- a/spec/parallel_spec.rb
+++ b/spec/parallel_spec.rb
@@ -4,7 +4,7 @@
 describe Parallel do
   worker_types = ["threads"]
   worker_types << "processes" if Process.respond_to?(:fork)
-  worker_types << "ractors" if defined?(Ractor) && RUBY_VERSION < "4.0.0" # TODO: need new code for ruby 4 ractors
+  worker_types << "ractors" if defined?(Ractor)
 
   def time_taken
     t = Time.now.to_f
@@ -31,7 +31,7 @@ def execute_start_and_kill(command, amount, signal = 'INT')
   end
 
   def without_ractor_warning(out)
-    out.sub(/.*Ractor is experimental.*\n/, "")
+    out.sub(/.*Ractor.*is experimental.*\n/, "")
   end
 
   describe ".processor_count" do