Node.js AdvancedLesson 92Free preview

Perf_hooks Module

This lesson is part of Node.js · All levels

Summary

This lesson discusses built-in perf_hooks modules for measuring code performance with high precision. You'll use performance.now() for short timing, performance.measureUserAgentSpecificMemory() for memory, and also a histogram to monitor latency. The module also provides an EventLoopDelay monitor to detect a jammed event loop. (Node.js)

Key points

Performance.now() gives a high-precision timestamp (decimal milliseconds) to measure duration.
The EventLoopDelay monitor creates a histogram delay event loop (mean, p99) for detecting blocking.
CreateHistogram measures the duration distribution of operations such as API response time.
(ELU) shows what percentage of the event loop is busy.
Performance.mark() and performance.measure() are suitable for measuring the application stage.

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