Use posix-spawn to spawn childprocess with timeout of 10 (configurable) seconds

Gemfile

@@ -95,6 +95,9 @@ gem 'ruby-duration', '~> 3.2.0'
 # provide compatible filesystem information for available storage
 gem 'sys-filesystem', '~> 1.1.4', require: false
 
+# Faster posix-compliant spawns for 8.0. conversions with pandoc
+gem 'posix-spawn', '~> 0.3.13', require: false
+
 gem 'bcrypt', '~> 3.1.6'
 
 gem 'multi_json', '~> 1.12.1'

Gemfile.lock

@@ -384,6 +384,7 @@ GEM
       activesupport (> 2.2.1)
       nokogiri (~> 1.8.1)
       rubyzip (~> 1.2.1)
+    posix-spawn (0.3.13)
     powerpack (0.1.1)
     prawn (2.2.2)
       pdf-core (~> 0.7.0)
@@ -680,6 +681,7 @@ DEPENDENCIES
   passenger (~> 5.3.3)
   pg (~> 1.0.0)
   plaintext (= 0.1.0)
+  posix-spawn (~> 0.3.13)
   prawn (~> 2.2)
   prawn-table (~> 0.2.2)
   pry-byebug (~> 3.6.0)

lib/open_project/text_formatting/formats/markdown/pandoc_wrapper.rb

@@ -28,7 +28,7 @@
 # See docs/COPYRIGHT.rdoc for more details.
 #++
 
-require 'open3'
+require 'posix-spawn'
 
 module OpenProject::TextFormatting::Formats
   module Markdown
@@ -97,18 +97,24 @@ module OpenProject::TextFormatting::Formats
       private
 
       ##
-      # Run pandoc through open3 and raise if an exception occurred
-      def run_pandoc!(args, **options)
-        output, stderr_str, status = Open3.capture3('pandoc', *args, **options)
-        raise stderr_str unless status.success?
+      # Run pandoc through posix-spawn and raise if an exception occurred
+      def run_pandoc!(command, stdin_data: nil, timeout: pandoc_timeout)
+        child = POSIX::Spawn::Child.new('pandoc', *command, input: stdin_data, timeout: timeout)
+        raise child.err unless child.status.success?
 
-        output
+        child.out
+      rescue POSIX::Spawn::TimeoutExceeded => e
+        raise Timeout::Error, "Timeout occurred while running pandoc: #{e.message}"
       end
 
       def read_usage_string
         run_pandoc! %w[--help]
       end
 
+      def pandoc_timeout
+        ENV.fetch('OPENPROJECT_PANDOC_TIMEOUT_SECONDS', 10).to_i
+      end
+
       def read_output_formats
         @output_formats ||= begin
           begin

lib/open_project/text_formatting/formats/markdown/textile_converter.rb

@@ -117,7 +117,6 @@ module OpenProject::TextFormatting::Formats
           # Iterate in batches to avoid plucking too much
           with_original_values_in_batches(klass, attributes) do |orig_values|
             markdowns_in_groups = bulk_convert_textile_with_fallback(orig_values, attributes)
-
             new_values = new_values_for(attributes, orig_values, markdowns_in_groups)
 
             next if new_values.empty?
@@ -198,11 +197,18 @@ module OpenProject::TextFormatting::Formats
 
         markdown = execute_pandoc_with_stdin! textile
 
-        cleanup_after_pandoc(markdown)
+        if markdown.empty?
+          markdown
+        else
+          cleanup_after_pandoc(markdown)
+        end
       end
 
       def execute_pandoc_with_stdin!(textile)
         pandoc.execute! textile
+      rescue Timeout::Error => e
+        warn "Execution of pandoc failed: #{e}"
+        ''
       rescue StandardError => e
         raise "Execution of pandoc failed: #{e}"
       end