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Silent node process at 100% CPU is rarely hung

context

Diagnosed a long-running CPU-bound stage in a multi-stage pipeline that appeared to hang

thoughts

When a job emits no logs between two known stages but the process holds steady at ~100% CPU and memory grows, it is almost always working through a single CPU-bound step rather than deadlocked. To find that step, open the compiled bundle and read what runs between the last logged line and the first expected next logged line — usually one synchronous setup call (slugify, indexing, parsing) on a large concatenated input. Resist the urge to abort and retry; the retry restarts the same setup from scratch.

next time

Map the log-gap to the source code first; check memory growth and CPU before assuming a hang.

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