From b77bfee0925e264ea5376913e4abd8ca2ad001a1 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Thu, 30 Jan 2025 09:34:01 +0100
Subject: [PATCH] Avoid calls to `require` in hotspots

Followup: https://github.com/ruby/psych/pull/686

This single call shows up as 4% of some controller actions
in the lobsters benchmark.

Profile: https://share.firefox.dev/3EqKnhS
---
 lib/psych/nodes/node.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/psych/nodes/node.rb b/lib/psych/nodes/node.rb
index 1a4ea553..6ae5c591 100644
--- a/lib/psych/nodes/node.rb
+++ b/lib/psych/nodes/node.rb
@@ -55,7 +55,8 @@ def to_ruby(symbolize_names: false, freeze: false, strict_integer: false)
       #
       # See also Psych::Visitors::Emitter
       def yaml io = nil, options = {}
-        require "stringio"
+        require "stringio" unless defined?(StringIO)
+
         real_io = io || StringIO.new(''.encode('utf-8'))
 
         Visitors::Emitter.new(real_io, options).accept self