mirror of
https://github.com/Shopify/liquid.git
synced 2026-09-17 18:00:41 -07:00
Tobi Lutke
c5a44be104
Major optimizations to reduce allocations and improve execution speed: 1. For loops: Replace catch/throw with while + break flag - Uses while loop with index instead of .each with catch/throw - Break implemented with flag variable, continue with next - Result: 18% fewer allocations, 85% faster for simple loops 2. Forloop property inlining - Inline forloop.index as (__idx__ + 1), forloop.first as (__idx__ == 0), etc. - Completely eliminates forloop hash allocation when all properties inlinable - Result: Loop with forloop went from +46% MORE to -16% FEWER allocations 3. LR.to_array helper with EMPTY_ARRAY constant - Centralized array conversion with frozen empty array for nil - Avoids allocations for empty collections 4. Inline LR.truthy? calls - Replace LR.truthy?(x) with (x != nil && x != false) - Eliminates method call overhead in conditions 5. Keep Time methods available in sandbox for date filter Overall results: - Allocations: 3.5% MORE -> 24% FEWER (27% improvement) - Time: 64% faster -> 89% faster (25% improvement) Also adds: - compile_profiler.rb for measuring allocations/performance - compile_acceptance_test.rb for output equivalence testing - OPTIMIZATION.md documenting optimization status
71 lines
2.1 KiB
Markdown
71 lines
2.1 KiB
Markdown
# Liquid Compiled Template Optimization Log
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This document tracks optimizations made to the compiled Liquid template engine.
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Each entry shows before/after code and measured impact.
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---
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## Baseline Measurement
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**Date:** 2024-12-31
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**Commit:** (pending profiler implementation)
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### Current State
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The compiled template engine generates Ruby code from Liquid templates.
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Before optimizations, here's a sample of generated code for a simple loop:
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```ruby
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# Template: {% for product in products %}{{ forloop.index }}: {{ product.name }}{% endfor %}
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->(assigns, __context__, __external__) do
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__output__ = +""
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__coll1__ = assigns["products"]
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__coll1__ = __coll1__.to_a if __coll1__.is_a?(Range)
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__len3__ = __coll1__.respond_to?(:length) ? __coll1__.length : 0
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__idx2__ = 0
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catch(:__loop__break__) do
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(__coll1__.respond_to?(:each) ? __coll1__ : []).each do |__item__|
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catch(:__loop__continue__) do
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assigns["product"] = __item__
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assigns['forloop'] = {
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'name' => "product-products",
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'length' => __len3__,
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'index' => __idx2__ + 1,
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'index0' => __idx2__,
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'rindex' => __len3__ - __idx2__,
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'rindex0' => __len3__ - __idx2__ - 1,
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'first' => __idx2__ == 0,
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'last' => __idx2__ == __len3__ - 1,
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}
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__output__ << LR.output(LR.lookup(assigns["forloop"], "index", __context__))
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__output__ << ": "
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__output__ << LR.output(LR.lookup(assigns["product"], "name", __context__))
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end
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__idx2__ += 1
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end
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end
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assigns.delete("product")
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assigns.delete('forloop')
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__output__
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end
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```
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### Issues Identified
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1. **catch/throw overhead** - Used even when no break/continue in loop
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2. **Hash allocation per iteration** - 8 key/value pairs computed every time
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3. **respond_to? checks** - Redundant after type is known
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4. **LR.lookup for forloop** - Unnecessary indirection for known hash
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5. **String literals not frozen** - Allocates on each render
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6. **Output buffer grows dynamically** - No pre-allocation
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---
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## Optimization Log
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<!-- Entries will be added here as optimizations are implemented -->
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