benchmark

name	benchmark
description	Run Go benchmarks and compare results to detect performance regressions. Use before and after performance-related changes.
disable-model-invocation	true
argument-hint	package-path

Performance Benchmarking

Run Go benchmarks to measure and compare performance. Flags regressions exceeding 10%.

Usage

• /benchmark - Run benchmarks on all packages
• /benchmark ./internal/index/... - Run benchmarks on specific package
• /benchmark -compare ./... - Compare against saved baseline

Steps

1. Identify benchmark targets

   • If $ARGUMENTS specifies a package, use that
   • Otherwise, find packages with *_test.go files containing Benchmark functions
   • Focus on performance-critical packages: internal/index/, internal/repo/, internal/api/

2. Run benchmarks

   go test -bench=. -benchmem -count=5 $ARGUMENTS 2>&1
   

   • Use -count=5 for statistical reliability
   • Use -benchmem to track allocations

3. Parse and analyze results For each benchmark, extract:

   • ns/op - Nanoseconds per operation
   • B/op - Bytes allocated per operation
   • allocs/op - Allocations per operation

4. Check for baseline comparison

   • Look for .benchmark-baseline file in project root
   • If -compare flag used and baseline exists, compare results

5. Report findings Format results as a table:

   | Benchmark | ns/op | B/op | allocs/op | Change |
   |-----------|-------|------|-----------|--------|
   

   Flag any metric that regressed more than 10% with a warning.

6. Offer to save baseline If no baseline exists or results improved, offer to save current results:

   go test -bench=. -benchmem -count=5 ./... > .benchmark-baseline
   

Performance-Critical Packages

Pay special attention to:

• internal/index/ - Trigram search (hot path)
• internal/repo/ - Repository access patterns
• internal/api/search/ - Search request handling
• internal/storage/ - S3 result compression

Example Output

Benchmark Results for ./internal/index/...

| Benchmark           | ns/op    | B/op  | allocs/op |
|---------------------|----------|-------|-----------|
| BenchmarkSearch-8   | 1234567  | 4096  | 12        |
| BenchmarkOpen-8     | 567890   | 8192  | 24        |

No regressions detected (threshold: 10%)