Node high CPU usage
High CPU in Node.js often comes from blocking the event loop, tight loops, hot JSON paths, regex backtracking, or too much work on a single process.
Common symptoms
- Node process tops CPU repeatedly
- Response latency rises sharply
- One instance becomes a hotspot
Likely causes
- Blocking CPU work inside request handlers
- Inefficient serialization or parsing
- Regex or loop pathologies
- Too much concurrency in one process
Evidence to look for
Single node PID stays above 40% CPU
CPU rises with traffic bursts
Perf capture shows hot JS/native frames
What it usually means
Node handles IO well, but CPU-heavy work on the main thread quickly creates latency and saturation.
What to do next
- 1Move heavy work to workers or queues
- 2Reduce blocking work in the request path
- 3Profile hot functions before scaling out
See what's causing your CPU
cpum.ai turns CPU, process, disk, and memory signals into plain-English explanations with evidence.
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