startup

Measures tracer startup overhead with and without a realistic dependency load surface. The signal is with-tracer-everything − control-everything: how much the tracer's loader hooks add when there's a representative dependency graph to wrap. See meta.json for the variant set.

The fixture

everything-fixture/ is a self-contained sub-project with its own package.json, package-lock.json, and node_modules. The bench loads it through a single require('./everything-fixture'). Stability properties:

dd-trace's own dependency tree (top-level deps, vendoring, hoisting) does not affect it.
A fixture dependency cutting a breaking release is pinned by the lockfile.
The package list lives in exactly one place (the manifest), so the require() list cannot drift away from the install set.
A missing module fails npm ci loudly before the benchmark runs.

The package set is curated for a realistic production Node.js application — web frameworks, HTTP clients, database drivers, message queues, loggers — biased toward modules that dd-trace instruments.

Updating the fixture

cd benchmark/sirun/startup/everything-fixture
# edit package.json
npm install
git add package.json package-lock.json

Do not commit node_modules/; runall.sh re-installs via npm ci.

The bench runs across the Node majors listed in .gitlab/benchmarks.yml (currently 20–26), so every pinned version must:

Have an engines.node range that includes the matrix floor, including all transitive dependencies after npm install resolves.
Be loadable through CJS require(). ESM-only releases (recent got, uuid) break the fixture's require(name) walk; pin a CJS-era version (e.g. got@11, uuid@9) instead.

Some top-level packages still satisfy (1) and (2) themselves but pull in transitive deps that bumped past the matrix floor. When that happens, add an overrides entry pinning the offending transitive dep to the last release that supports the floor; do not downgrade the top-level package unless it has no other compatible release.