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Shelley Vohr
ddc0a0aa28
Every `new Worker()` runs the whole internal bootstrap (realm, node, web exposure, thread and process-state switches) in its fresh isolate, compiling ~80 builtins with the code cache; only the main thread deserializes its principal context from the built-in snapshot. That bootstrap is about half of a worker's cold start. The bootstrapped principal context in the snapshot is nearly thread-neutral: the worker-side switch scripts (is_not_main_thread, does_not_own_process_state) are written as overrides of the main-thread ones, and the per-thread values of the `worker` binding were the only thread-specific data baked into the context. Let a worker deserialize that same context and EnvSerializeInfo and apply the two worker-side switches on top: - worker binding: threadId, threadName, isMainThread, isInternalThread, ownsProcessState and resourceLimits become lazy properties of the per-isolate template, computed from the Environment on first read. - CreateEnvironment(): when a worker (its IsolateData has a Worker) passes an empty context, deserialize kNodeMainContextIndex and run internal/bootstrap/switches/is_not_main_thread and, unless the worker owns process state, does_not_own_process_state after InitializeMainContext(). - Worker::Run(): take that path when the embedded built-in snapshot is in use (not an embedder's or a --snapshot-blob one, which has run application code), browser globals are not disabled and --no-worker-snapshot was not given; otherwise bootstrap as before. - is_not_main_thread.js: also delete _debugPause and the profiler idle notifier helpers that is_main_thread.js installs. - pre_execution: run the snapshot's deserialize callbacks (Buffer pool, default resolver, cached cwd) on worker threads too, now that a worker can come from a snapshot. - --[no-]worker-snapshot per-isolate option, documented. Sequential new Worker() -> 'online' -> terminate goes from ~20.9 ms to ~10.3 ms per worker on x64 Linux; --no-worker-snapshot restores the old number. Signed-off-by: Shelley Vohr <shelley.vohr@gmail.com> PR-URL: https://github.com/nodejs/node/pull/65336 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>