perf(runtime): use dd-trace loader registration - #819
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Direct Module.register() forces a loader worker even when the installed tracer supports in-process hooks. Loading the function-local tracer registration entry preserves preload and older-runtime fallbacks. Paired Lambda trials reduced module load by 79.549 ms and startup total by 65.788 ms (21.47%).
Function-local dd-trace v5.5 has loader-hook.mjs but no register.js. The fallback preserves ESM instrumentation while newer tracers use their optimized registration entry point.
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Three conflicts, all resolved as unions of both sides: - src/handler.mjs: main (#819) moved the ESM loader-hook registration out of handler.mjs into initTracer() in src/runtime/module_importer.js, so this branch's copy of esmLoaderAlreadyRegistered() and the Module.register() block are dropped in favor of main's. Kept this branch's new DD_TRACE_STARTUP_LOGS default. dd-trace 6.12.0 ships both register.js and loader-hook.mjs, so main's registration path works on the v6 line. - integration_tests/container/cjs/Dockerfile: kept this branch's DD_TRACE_VERSION build-arg + `npm pkg set` override alongside main's `COPY package.json *.js` for the new manual-wrap fixture handlers. - integration_tests/container/cjs/package.json: main's axios pin plus this branch's dd-trace 6.12.0. main's integration_tests_local/run.sh already probes for scripts/install_deps.sh and scripts/dd_trace_versions.sh and passes --build-arg DD_TRACE_VERSION, so the new local harness picks up the per-runtime tracer split without changes. Verified: yarn build, yarn test (638 tests, 52 suites — including main's new src/handler.spec.ts and src/runtime/module-importer.spec.ts), yarn lint and yarn check-formatting all pass against dd-trace 6.12.0. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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Load the function-local
dd-traceregistration entry during tracer initialization instead of registering another loader hook from the Lambda wrapper.Direct
Module.register()creates a loader worker and synchronous startup communication. The canonical entry can select in-process hooks. Older function-local tracers withoutregister.jsretain the direct fallback.Paired Lambda trials reduced module load by 79.549 ms and startup total by 65.788 ms (21.47%). A fresh local Node 22.23.2 benchmark across 40 alternating pairs reduced module load by 45.881 ms and startup total by 45.264 ms (15.54%).