Analyze if the Ruby hashing algorithm could be improved using Tabulation Hashing. This is a project for my Advanced Algorithms course by Alexandr Andoni at Columbia University.

The written C code for the project is in the tabulation_project branch of my fork of the Ruby project (MRI) in GitHub.

Ruby issue: https://bugs.ruby-lang.org/issues/16851

benchmark_tabulation.rb benchmarks the insertion of 600000 elements (by hashing their 64 bits ids) in an empty hash 100 times. Below are the times (in seconds) I got executing this code for different versions of the Ruby code:

• master (without Simple Tabulation): 29.68
• master with Linear Probing (without Simple Tabulation): 99.76
• master with Quadratic Probing (without Simple Tabulation): 29.97
• master with Simple Tabulation: 15.76
• master with Linear Probing and Simple Tabulation: 24.23
• master with Quadratic Probing and Simple Tabulation: 13.73

master refers to ruby 2.8.0dev: (2020-05-07T16:22:38Z master 7ded8fd) [x86_64-linux]. I tried with 8 x Intel i5-8265U.

This prove the potential of Simple Tabulation to improve current Ruby implementation. For more details check the project report: latex/RubyTabulation_Project.pdf.

Code published under GNU GENERAL PUBLIC LICENSE v3 (see LICENSE).