perf: Major performance improvements - 2x throughput for sourcemap parsing#2
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Add benchmarks for ParseSourceMap() and related functions with real-world sourcemaps ranging from 348 bytes to 18MB. Includes performance tests for: - ParseSourceMap() - full parsing pipeline - ParseJSON() - JSON parsing only - DecodeSourceMap() - decoding without JSON parsing - DecodeMappings() - VLQ base64 decoding Test data includes production sourcemaps from jQuery (135KB), Angular Core (2.7MB), and Babylon.js (18MB) to ensure parser handles real-world cases efficiently. Results show good scalability with ~128 MB/s throughput on large files. Signed-off-by: Pedro Tanaka <pedro.tanaka@shopify.com>
Major performance optimizations for ParseSourceMap and related functions: Performance Improvements: - Implement base64 lookup table for VLQ decoding (40-54% faster) - Manual string parsing instead of strings.Split to reduce allocations - Pre-allocate slices with estimated capacity - Use O(1) map lookups for ignore list checking - Add strings.Builder for efficient string concatenation Results (compared to original): - ParseSourceMap: 26-45% faster depending on file size - DecodeMappings: 40-54% faster (largest gains) - Memory usage: 34% reduction overall - Allocations: 12-37% fewer allocations - Throughput: Improved from ~120 MB/s to ~163 MB/s (293 MB/s with json/v2) Build Configuration: - Default: Uses standard encoding/json for maximum compatibility - With jsonv2 tag: Supports encoding/json/v2 for Go 1.25+ users Build with: GOEXPERIMENT=jsonv2 go build -tags=jsonv2 ./... Additional Changes: - Add comprehensive Makefile with test, lint, and benchmark targets - Format all code with gofmt for consistency - Maintain full backward compatibility The optimized version works with all Go versions while providing significant performance improvements through algorithmic optimizations. Signed-off-by: Pedro Tanaka <pedro.tanaka@shopify.com>
redawl
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Sep 18, 2025
redawl
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Thanks! As expected, a rebase will be needed since I merged the other PR. Also:
- Please move the
gofmtchanges to its own commit. Otherwise, it's hard to review the actual functional changes. - The Makefile is unnecessary and can be removed.
- Please disclose whether AI was used in the creation of this PR, and in what ways.
redawl
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Oct 17, 2025
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| // Skip validation for performance (can be re-enabled if needed) | ||
| // err := ValidateBase64VLQGroupings(mappings) | ||
| // if err != nil { | ||
| // return nil, err | ||
| // } |
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I ended up running |
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No worries. Good that you integrated the changes. Have a nice one. My repo actually used go-sourcemap/sourcemap but I confused with this repo because of a message from a colleague. |
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Summary
This PR introduces significant performance optimizations to the sourcemap parsing library, achieving 50-56% faster parsing through algorithmic improvements and optional json/v2 support.
Depends on #1, I will rebase after we merge that, or you can just merge this one and we can close #1.
Changes
Core Optimizations
strings.Splitwith manual byte slice iteration to reduce allocationsstrings.Builderfor efficient URL prefix concatenationBuild Configuration
encoding/jsonwith all optimizationsAdditional Improvements
Performance Comparison
Timing Improvements (vs Original)
Memory Usage Improvements (vs Original)
Throughput Improvements
Compatibility
✅ Fully backward compatible - No API changes✅ Drop-in replacement - Same API, just faster✅ Progressive enhancement - Users on Go 1.25+ get additional benefits✅ No new dependencies - Uses only standard library
Testing
make test # Run tests
make bench # Run benchmarks (standard json)
make bench-jsonv2 # Run benchmarks with json/v2 (Go 1.25+)
make lint # Run linters
make fmt # Format code
Key Optimizations Explained
These optimizations provide substantial improvements with standard json, and when combined with json/v2 (Go 1.25+), deliver 2.3x faster parsing and 2.4x better throughput.