From 596da98b3ff28ff48b10aed0bbe75287862eacbb Mon Sep 17 00:00:00 2001
From: Kenta Murata <mrkn@mrkn.jp>
Date: Mon, 21 Dec 2020 15:45:50 +0900
Subject: [PATCH] [json] Make JSON.create_id thread-safe

---
 ext/json/lib/json/common.rb | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/ext/json/lib/json/common.rb b/ext/json/lib/json/common.rb
index c34fa61eb7..747effee12 100644
--- a/ext/json/lib/json/common.rb
+++ b/ext/json/lib/json/common.rb
@@ -109,7 +109,20 @@ module JSON
     #   JSON.create_id # => 'json_class'
     attr_accessor :create_id
   end
-  self.create_id = 'json_class'
+
+  DEFAULT_CREATE_ID = 'json_class'.freeze
+  private_constant :DEFAULT_CREATE_ID
+
+  CREATE_ID_TLS_KEY = "JSON.create_id".freeze
+  private_constant :CREATE_ID_TLS_KEY
+
+  def self.create_id
+    Thread.current[CREATE_ID_TLS_KEY] || DEFAULT_CREATE_ID
+  end
+
+  def self.create_id=(new_value)
+    Thread.current[CREATE_ID_TLS_KEY] = new_value.dup.freeze
+  end
 
   NaN           = 0.0/0