Shopify / Shopify/liquid

Slow for loops

Open
#678 5 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Performance
Dominant language
Ruby
Stars
11.9k
Forks
1.5k
Avg merge
17h 55m
Merged PRs (30d)
3

Description

I've been running into some performance issues with for loops being slow when iterating over lots of items. It seems that even when the for loop has no body it's still quite slow.

I've put together a benchmark which reproduces this problem with some real-world data I've been working with. https://gist.github.com/chrismytton/a34ace5123c27e11dd55

Related to https://github.com/Shopify/liquid/issues/508

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the benchmark in the linked gist and read the related discussion in Shopify/liquid issue #508. Use those reproductions to locate the for-loop implementation and measure the empty-body case. Done means the benchmark shows improved performance without changing loop behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
ruby
Domain
performance
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.