From 936899aa7a7fa042ec4b2cfdf1f1269b215b2070 Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@shopify.com>
Date: Wed, 29 Jul 2026 20:54:16 +1200
Subject: [PATCH] Reset blocked operations after fork.

---
 lib/async/scheduler.rb |  1 +
 releases.md            |  4 ++++
 test/process/fork.rb   | 23 +++++++++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/lib/async/scheduler.rb b/lib/async/scheduler.rb
index 45f972fa..46610357 100644
--- a/lib/async/scheduler.rb
+++ b/lib/async/scheduler.rb
@@ -685,6 +685,7 @@ def process_fork
 			@children = nil
 			@selector = nil
 			@timers = nil
+			@blocked = 0
 			
 			# Close the scheduler:
 			Fiber.set_scheduler(nil)
diff --git a/releases.md b/releases.md
index db113ed9..420aae5c 100644
--- a/releases.md
+++ b/releases.md
@@ -1,5 +1,9 @@
 # Releases
 
+## Unreleased
+
+  - Fixed scheduler cleanup after forking while other fibers are blocked.
+
 ## v2.43.0
 
   - Propagate cancellation causes through task trees so child tasks observe the original cancellation cause.
diff --git a/test/process/fork.rb b/test/process/fork.rb
index 42885389..8b28c0c3 100644
--- a/test/process/fork.rb
+++ b/test/process/fork.rb
@@ -44,5 +44,28 @@
 				Process.waitpid(pid) if pid
 			end
 		end
+		
+		it "can fork while another fiber is blocked" do
+			r, w = IO.pipe
+			queue = Thread::Queue.new
+			
+			Async do |task|
+				blocked_task = task.async do
+					queue.pop
+				end
+				
+				pid = Process.fork do
+					# Child process:
+					w.write("hello")
+				end
+				
+				# Parent process:
+				w.close
+				expect(r.read).to be == "hello"
+			ensure
+				blocked_task&.stop
+				Process.waitpid(pid) if pid
+			end
+		end
 	end
 end