topic / runtime-execution

Runtime & Execution

Watch functions, objects, events, and I/O move while a program runs.

Trace program startup, function calls, stack frames, heap allocation, garbage collection, asynchronous queues, runtime libraries, and operating-system interactions.

1 article · 1 video · 1 trace · 1 request flow · 1 interview · 5 total

Articles

runtime executionSep 25, 2026

Async Code Still Runs Somewhere

Separate JavaScript callbacks, event-loop scheduling, operating-system I/O, and worker-pool tasks in an asynchronous program.

7 min readRead

Request Flows

request flow · 5 stagesOne Event Loop Turn Resumes Asynchronous WorkFollow a callback, a pending operation, its completion notification, queued promise work, and the next JavaScript continuation.

Videos

In production

runtime executionSep 25, 2026

What Node.js Does While JavaScript Awaits

A planned timeline separates JavaScript execution, promise suspension, I/O progress, completion notification, and continuation jobs.

Details

Traces

trace 01 · runtimeTrace a Node.js async Function ResumingFollow synchronous JavaScript, a pending promise, an I/O completion, and the queued continuation without treating await as a new thread.

Interviews

medium · t2Does await Run the Rest of the Function on Another Thread?A runtime prompt about promise suspension, event-loop scheduling, I/O completion, worker pools, and CPU-bound callbacks.

Explore adjacent

programming language internals computer systems operating systems performance engineering function calls and stack frames heap and garbage collection event loops and async

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