@angular/benchpress

A browser benchmarking library used by Angular's own performance suite. Lets test code drive a browser through repeated iterations of a workload and collect statistics from Chrome's tracing/performance APIs.

Purpose

@angular/benchpress provides:

• A Runner that drives the browser through a configurable sample loop.
• Metrics collectors that read browser performance traces (heap, paint, layout, script).
• Validators that decide when a benchmark has gathered enough samples to be statistically meaningful.
• Reporters that write CSV / JSON output for the perf comparison workflow.

Directory layout

packages/benchpress/
├── src/
│   ├── runner.ts
│   ├── metric/             # Metric implementations
│   ├── validator/          # Sample-count validators
│   ├── reporter/           # CSV / JSON / multi-reporter
│   ├── webdriver/          # Webdriver adapters
│   └── ...
└── public_api.ts

Key abstractions

Type	File	What it is
Runner	packages/benchpress/src/runner.ts	The top-level driver.
Metric	packages/benchpress/src/metric.ts	Base class for metric collectors.
Validator	packages/benchpress/src/validator.ts	Decides when a sample set is sufficient.
Reporter	packages/benchpress/src/reporter.ts	Writes results.

Usage

The benchmark suites under modules/benchmarks/ drive Benchpress. The pnpm benchmarks script runs a representative subset locally; CI runs the full set on dedicated hardware via the perf.yml and benchmark-compare.yml workflows.

Integration points

• modules/benchmarks/ — the actual benchmark workloads.
• scripts/benchmarks/index.mts — the local-runner orchestration.
• CI perf workflows — .github/workflows/perf.yml and benchmark-compare.yml consume Benchpress output.

Status

Benchpress is internal-leaning: it ships on npm but is rarely used outside Angular and a few sister projects. Treat it as a stable but unflashy testing tool.