From 97582101f589fae634e05bf33112b09e8c64f54f Mon Sep 17 00:00:00 2001
From: firejox <firejox@gmail.com>
Date: Sun, 29 Sep 2019 16:46:12 +0800
Subject: [PATCH] Keep Channel#close thread-safety

---
 src/channel.cr | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/channel.cr b/src/channel.cr
index 74de802ab3a8..62b268551505 100644
--- a/src/channel.cr
+++ b/src/channel.cr
@@ -92,17 +92,19 @@ class Channel(T)
   end
 
   def close
-    @closed = true
+    @lock.sync do
+      @closed = true
 
-    @senders.each &.fiber.enqueue
+      @senders.each &.fiber.enqueue
 
-    @receivers.each do |receiver|
-      receiver.state_ptr.value = DeliveryState::Closed
-      receiver.fiber.enqueue
-    end
+      @receivers.each do |receiver|
+        receiver.state_ptr.value = DeliveryState::Closed
+        receiver.fiber.enqueue
+      end
 
-    @senders.clear
-    @receivers.clear
+      @senders.clear
+      @receivers.clear
+    end
     nil
   end