bench-devloop.yml

# Dev-loop timings on a CI-shaped runner (`make bench-devloop` with cold and
# warm caches): build, generate, lint per linter, probes, tests per package
# with and without -race, and an A/B of the CI test run against a base ref on
# the same machine (separate runs land on different machines; their noise
# hides changes of tens of percent). The report is the run's summary page.
# Run it by hand (Actions > Bench dev loop), or push a branch to bench/<name>
# to compare it with the branch work lands on (dev, or main without one:
# scripts/branches.sh).
name: Bench dev loop

on:
  workflow_dispatch:
    inputs:
      base:
        description: Ref to compare against (A/B of the test run on the same machine; empty = origin/dev, else origin/main)
        default: ''
      rounds:
        description: Alternating A/B rounds (the median is compared)
        default: '3'
  push:
    branches: ['bench/**']

permissions:
  contents: read

concurrency:
  group: bench-${{ github.ref }}
  cancel-in-progress: true

jobs:
  bench:
    runs-on: ubuntu-latest
    timeout-minutes: 60
    env:
      TEST_DATABASE_URL: postgres://postgres:postgres@127.0.0.1:5432/postgres?sslmode=disable
      BENCH_BASE: ${{ inputs.base }}
      BENCH_ROUNDS: ${{ inputs.rounds || '3' }}
    steps:
      # Same Postgres as CI's db shard.
      - name: Start Postgres
        run: |
          docker run -d --name pg -p 5432:5432 -e POSTGRES_PASSWORD=postgres \
            --tmpfs /var/lib/postgresql postgres:18-alpine \
            -c fsync=off -c synchronous_commit=off -c full_page_writes=off -c max_connections=200
      - uses: actions/checkout@v7
        with:
          fetch-depth: 0 # the A/B base ref
      # Read-only: the module cache CI saves. Build and lint caches start
      # empty on purpose; the bench measures cold and warm itself.
      - uses: actions/cache/restore@v6
        with:
          path: ~/go/pkg/mod
          key: v7-gomod-${{ runner.os }}-${{ hashFiles('go.sum') }}
          restore-keys: v7-gomod-${{ runner.os }}-
      - name: Go toolchain and modules
        run: |
          go version
          go mod download
          go mod download -modfile=tools/go.mod
      - name: Wait for Postgres
        run: |
          for _ in $(seq 1 120); do docker exec pg pg_isready -q -h 127.0.0.1 -U postgres && exit 0; sleep 0.5; done
          docker logs pg; exit 1
      - name: Bench
        run: |
          . scripts/branches.sh
          BENCH_BASE=${BENCH_BASE:-$(landing_ref)} make bench-devloop BENCH_COLD=1