Performance fixes

[jperville]

Summary

This PR contains all the improvements I made from profiling the JSON::LD::API#frame method.

If all commits from this PR and sister PR https://github.com/ruby-rdf/rdf/pull/360 are applied, the number of objects allocated in my sample scenario drops around 32% and the runtime is improved by 20% (on Ruby 2.4, which is recommended because of the frozen string literal feature).

I would appreciate if you can do some code review before accepting the PR @gkellogg .

The details

I did not have the chance to run the whole json-ld test suite (broken since #40) but at least for each commit I verified that the CI=true bundle exec rake spec command passes, and that there is no regression in the ntriple representation of the graph that I have been framing.

This PR was developed using a sample scenario (ntriples graph that we want to frame to a certain context). The scenario was run multiple times (here 10) and I kept track of ruby object allocations using stackprof.

The sample scenario run 10 times would allocate 906000 objects at the start, and at the end only 623000, a reduction of around 32% of allocated objects. The run time was cut by around 20% (on ruby 2.4).

Here was my progression in reducing the allocated object count (each step should have a corresponding commit in this PR):

• starting with 906120 objects allocated.
• json-ld:
  • [+1k] replace KEYWORDS=%w[] with a Set (to optimize multiple .include calls) => 907840
  • [-64k] rework Array#kw_sort to use a cache of KW_ORDERS for faster lookups and less object allocations => 843600
  • [-24k] remplace mystring[0,2] == '//' with mystring.start_with?('//') => 819770
  • [-10k] remove 1 line of expensive unused code: keys = ordered ? input.keys.kw_sort : input.keys => 809580
  • [-45k] hunt uses of .keys.any?, .keys.include?, .keys == %w(), .keys.length => 764350
  • [-19k] hunt use of .keys.reject .keys.select, keys.inject ... => 745730
  • [-29k] hunt use of %w().include? and ].include? => 716860
  • [-3k] hunt use of == [], == {}, != [], != {} , replace with .empty? predicate => 713610
  • [-10k] replace (object.keys & %w[value1 value2]).length < 2 with if !(object.key?(value1) && object.key?(value2)) => 703930
  • [-1k] refactor .reject.each and .reject.map to not allocate temporary array (thanks 'next if') => 702900
  • [-10k] refactor output_object.delete('@type') if Array(output_object['@type']).join('').to_s.empty? en output_object.delete('@type') if output_object.key?('@type') && output_object['@type'].nil? => 692020
  • [-8k] replace all use of .inject with more efficient .each_with_object => 684590
  • [-7k] replace map..flatten.compact instance with .each_with_object => 677990
  • [-0k] replace mapping -= %w('@set') with mapping.delete('@set') => 677990
  • [-0k] replace .dup.delete_if with .reject => 677990
  • [-16k] replace defined: {} in function keyword args with defined: nil followed with defined = defined || {} because parameter seldom used => 661760
  • [-4k] refactor JSON::LD::Frame#count_blank_node_identifiers to allocate results hash only once => 657870
• rdf:
  • [-6k] replace matchdata.to_a[1..-1] with matchdata[1..-1] => 651111
  • [-18k] replace def method(*args) if (first=args.first) ... with def method(first, *args) => 633651
  • [-7k] replace property.to_s =~ /regexp/ with constant regexp and REGEXP.match(property) (regexp.match cares about casting nil and symbol to String) => 626961
  • [-3k] reduce unneeded object allocations in RDF::Utils::Logger#logger_common => 623851

[coveralls]

Coverage increased (+0.1%) to 89.07% when pulling 178afc2c014d69db75bd9447ed3cb166f98ee055 on PerfectMemory:performance-fixes into a1a01db875afbb8759b0cac10b7d1aa73034a3d8 on ruby-rdf:develop.

[coveralls]

Coverage increased (+0.1%) to 89.07% when pulling 178afc2c014d69db75bd9447ed3cb166f98ee055 on PerfectMemory:performance-fixes into a1a01db875afbb8759b0cac10b7d1aa73034a3d8 on ruby-rdf:develop.

[coveralls]

Coverage increased (+0.1%) to 89.07% when pulling 178afc2c014d69db75bd9447ed3cb166f98ee055 on PerfectMemory:performance-fixes into a1a01db875afbb8759b0cac10b7d1aa73034a3d8 on ruby-rdf:develop.

[jperville]

Hello @gkellogg , could you cut a new release of json-ld gem? Thank you very much.

[gkellogg]

Released as 2.1.6.