From 37e8a16d68aa94273507007f6440a092db60fb45 Mon Sep 17 00:00:00 2001
From: Ashwin Maroli <ashmaroli@gmail.com>
Date: Wed, 19 Feb 2020 14:07:28 +0530
Subject: [PATCH 1/3] Subclass Kramdown::Document to reduce allocations

---
 .../converters/markdown/kramdown_parser.rb    | 52 ++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/lib/jekyll/converters/markdown/kramdown_parser.rb b/lib/jekyll/converters/markdown/kramdown_parser.rb
index 64bb1d1c8d2..5f71e46eca7 100644
--- a/lib/jekyll/converters/markdown/kramdown_parser.rb
+++ b/lib/jekyll/converters/markdown/kramdown_parser.rb
@@ -1,5 +1,55 @@
 # Frozen-string-literal: true
 
+module Kramdown
+  # A Kramdown::Document subclass meant to optimize memory usage from initializing
+  # a kramdown document for parsing.
+  #
+  # The optimization is by using the same options Hash (and its derivatives) for
+  # converting all Markdown documents in a Jekyll site.
+  class JekyllDocument < Document
+    class << self
+      attr_reader :options, :parser
+
+      # The implementation is basically the core logic in +Kramdown::Document#initialize+
+      #
+      # rubocop:disable Naming/MemoizedInstanceVariableName
+      def setup(options)
+        @options ||= Options.merge(options).freeze
+        @parser  ||= begin
+          parser_name = (@options[:input] || "kramdown").to_s
+          parser_name = parser_name[0..0].upcase + parser_name[1..-1]
+          try_require("parser", parser_name)
+
+          if Parser.const_defined?(parser_name)
+            Parser.const_get(parser_name)
+          else
+            raise Kramdown::Error, "kramdown has no parser to handle the specified " \
+                                   "input format: #{@options[:input]}"
+          end
+        end
+      end
+      # rubocop:enable Naming/MemoizedInstanceVariableName
+
+      private
+
+      def try_require(type, name)
+        require "kramdown/#{type}/#{Utils.snake_case(name)}"
+      rescue LoadError
+        false
+      end
+    end
+
+    def initialize(source, options = {})
+      JekyllDocument.setup(options)
+
+      @options = JekyllDocument.options
+      @root, @warnings = JekyllDocument.parser.parse(source, @options)
+    end
+  end
+end
+
+#
+
 module Jekyll
   module Converters
     class Markdown
@@ -37,7 +87,7 @@ def setup
         end
 
         def convert(content)
-          document = Kramdown::Document.new(content, @config)
+          document = Kramdown::JekyllDocument.new(content, @config)
           html_output = document.to_html
           if @config["show_warnings"]
             document.warnings.each do |warning|

From d66facb4972a245052ea8d6446140ffd5ec4b298 Mon Sep 17 00:00:00 2001
From: Ashwin Maroli <ashmaroli@gmail.com>
Date: Wed, 19 Feb 2020 15:46:21 +0530
Subject: [PATCH 2/3] Reset variables if set up with different options

---
 lib/jekyll/converters/markdown/kramdown_parser.rb | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/jekyll/converters/markdown/kramdown_parser.rb b/lib/jekyll/converters/markdown/kramdown_parser.rb
index 5f71e46eca7..0c64605ef7e 100644
--- a/lib/jekyll/converters/markdown/kramdown_parser.rb
+++ b/lib/jekyll/converters/markdown/kramdown_parser.rb
@@ -14,6 +14,11 @@ class << self
       #
       # rubocop:disable Naming/MemoizedInstanceVariableName
       def setup(options)
+        @cache ||= {}
+        @cache[:id] ||= options.hash
+
+        # reset variables on a subsequent set up with a different options Hash
+        reset! unless @cache[:id] == options.hash
         @options ||= Options.merge(options).freeze
         @parser  ||= begin
           parser_name = (@options[:input] || "kramdown").to_s
@@ -32,6 +37,10 @@ def setup(options)
 
       private
 
+      def reset!
+        @options = @parser = @cache[:id] = nil
+      end
+
       def try_require(type, name)
         require "kramdown/#{type}/#{Utils.snake_case(name)}"
       rescue LoadError

From 73c05aae8abcaa845f42d34d91234e3e347bb3f9 Mon Sep 17 00:00:00 2001
From: Ashwin Maroli <ashmaroli@gmail.com>
Date: Wed, 19 Feb 2020 23:37:56 +0530
Subject: [PATCH 3/3] Reset variables if set up with different options

---
 lib/jekyll/converters/markdown/kramdown_parser.rb | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/lib/jekyll/converters/markdown/kramdown_parser.rb b/lib/jekyll/converters/markdown/kramdown_parser.rb
index 0c64605ef7e..aebd6ee7fef 100644
--- a/lib/jekyll/converters/markdown/kramdown_parser.rb
+++ b/lib/jekyll/converters/markdown/kramdown_parser.rb
@@ -15,10 +15,13 @@ class << self
       # rubocop:disable Naming/MemoizedInstanceVariableName
       def setup(options)
         @cache ||= {}
-        @cache[:id] ||= options.hash
 
         # reset variables on a subsequent set up with a different options Hash
-        reset! unless @cache[:id] == options.hash
+        unless @cache[:id] == options.hash
+          @options = @parser = nil
+          @cache[:id] = options.hash
+        end
+
         @options ||= Options.merge(options).freeze
         @parser  ||= begin
           parser_name = (@options[:input] || "kramdown").to_s
@@ -37,10 +40,6 @@ def setup(options)
 
       private
 
-      def reset!
-        @options = @parser = @cache[:id] = nil
-      end
-
       def try_require(type, name)
         require "kramdown/#{type}/#{Utils.snake_case(name)}"
       rescue LoadError