/**
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* This module provides an implementation of a subset of the W3C [Web Performance APIs](https://w3c.github.io/perf-timing-primer/) as well as additional APIs for
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* Node.js-specific performance measurements.
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*
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* Node.js supports the following [Web Performance APIs](https://w3c.github.io/perf-timing-primer/):
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*
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* * [High Resolution Time](https://www.w3.org/TR/hr-time-2)
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* * [Performance Timeline](https://w3c.github.io/performance-timeline/)
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* * [User Timing](https://www.w3.org/TR/user-timing/)
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*
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* ```js
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* const { PerformanceObserver, performance } = require('perf_hooks');
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*
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* const obs = new PerformanceObserver((items) => {
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* console.log(items.getEntries()[0].duration);
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* performance.clearMarks();
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* });
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* obs.observe({ type: 'measure' });
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* performance.measure('Start to Now');
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*
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* performance.mark('A');
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* doSomeLongRunningProcess(() => {
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* performance.measure('A to Now', 'A');
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*
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* performance.mark('B');
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* performance.measure('A to B', 'A', 'B');
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* });
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* ```
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* @see [source](https://github.com/nodejs/node/blob/v17.0.0/lib/perf_hooks.js)
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*/
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declare module 'perf_hooks' {
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import { AsyncResource } from 'node:async_hooks';
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type EntryType = 'node' | 'mark' | 'measure' | 'gc' | 'function' | 'http2' | 'http';
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interface NodeGCPerformanceDetail {
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/**
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* When `performanceEntry.entryType` is equal to 'gc', `the performance.kind` property identifies
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* the type of garbage collection operation that occurred.
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* See perf_hooks.constants for valid values.
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*/
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readonly kind?: number | undefined;
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/**
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* When `performanceEntry.entryType` is equal to 'gc', the `performance.flags`
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* property contains additional information about garbage collection operation.
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* See perf_hooks.constants for valid values.
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*/
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readonly flags?: number | undefined;
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}
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/**
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* @since v8.5.0
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*/
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class PerformanceEntry {
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protected constructor();
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/**
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* The total number of milliseconds elapsed for this entry. This value will not
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* be meaningful for all Performance Entry types.
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* @since v8.5.0
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*/
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readonly duration: number;
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/**
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* The name of the performance entry.
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* @since v8.5.0
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*/
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readonly name: string;
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/**
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* The high resolution millisecond timestamp marking the starting time of the
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* Performance Entry.
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* @since v8.5.0
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*/
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readonly startTime: number;
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/**
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* The type of the performance entry. It may be one of:
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*
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* * `'node'` (Node.js only)
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* * `'mark'` (available on the Web)
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* * `'measure'` (available on the Web)
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* * `'gc'` (Node.js only)
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* * `'function'` (Node.js only)
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* * `'http2'` (Node.js only)
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* * `'http'` (Node.js only)
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* @since v8.5.0
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*/
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readonly entryType: EntryType;
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/**
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* Additional detail specific to the `entryType`.
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* @since v16.0.0
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*/
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readonly detail?: NodeGCPerformanceDetail | unknown | undefined; // TODO: Narrow this based on entry type.
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}
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/**
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* _This property is an extension by Node.js. It is not available in Web browsers._
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*
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* Provides timing details for Node.js itself. The constructor of this class
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* is not exposed to users.
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* @since v8.5.0
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*/
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class PerformanceNodeTiming extends PerformanceEntry {
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/**
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* The high resolution millisecond timestamp at which the Node.js process
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* completed bootstrapping. If bootstrapping has not yet finished, the property
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* has the value of -1.
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* @since v8.5.0
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*/
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readonly bootstrapComplete: number;
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/**
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* The high resolution millisecond timestamp at which the Node.js environment was
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* initialized.
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* @since v8.5.0
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*/
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readonly environment: number;
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/**
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* The high resolution millisecond timestamp of the amount of time the event loop
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* has been idle within the event loop's event provider (e.g. `epoll_wait`). This
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* does not take CPU usage into consideration. If the event loop has not yet
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* started (e.g., in the first tick of the main script), the property has the
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* value of 0.
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* @since v14.10.0, v12.19.0
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*/
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readonly idleTime: number;
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/**
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* The high resolution millisecond timestamp at which the Node.js event loop
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* exited. If the event loop has not yet exited, the property has the value of -1\.
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* It can only have a value of not -1 in a handler of the `'exit'` event.
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* @since v8.5.0
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*/
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readonly loopExit: number;
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/**
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* The high resolution millisecond timestamp at which the Node.js event loop
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* started. If the event loop has not yet started (e.g., in the first tick of the
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* main script), the property has the value of -1.
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* @since v8.5.0
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*/
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readonly loopStart: number;
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/**
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* The high resolution millisecond timestamp at which the V8 platform was
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* initialized.
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* @since v8.5.0
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*/
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readonly v8Start: number;
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}
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interface EventLoopUtilization {
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idle: number;
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active: number;
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utilization: number;
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}
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/**
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* @param util1 The result of a previous call to eventLoopUtilization()
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* @param util2 The result of a previous call to eventLoopUtilization() prior to util1
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*/
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type EventLoopUtilityFunction = (util1?: EventLoopUtilization, util2?: EventLoopUtilization) => EventLoopUtilization;
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interface MarkOptions {
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/**
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* Additional optional detail to include with the mark.
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*/
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detail?: unknown | undefined;
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/**
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* An optional timestamp to be used as the mark time.
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* @default `performance.now()`.
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*/
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startTime?: number | undefined;
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}
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interface MeasureOptions {
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/**
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* Additional optional detail to include with the mark.
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*/
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detail?: unknown | undefined;
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/**
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* Duration between start and end times.
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*/
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duration?: number | undefined;
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/**
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* Timestamp to be used as the end time, or a string identifying a previously recorded mark.
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*/
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end?: number | string | undefined;
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/**
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* Timestamp to be used as the start time, or a string identifying a previously recorded mark.
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*/
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start?: number | string | undefined;
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}
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interface TimerifyOptions {
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/**
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* A histogram object created using
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* `perf_hooks.createHistogram()` that will record runtime durations in
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* nanoseconds.
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*/
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histogram?: RecordableHistogram | undefined;
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}
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interface Performance {
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/**
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* If name is not provided, removes all PerformanceMark objects from the Performance Timeline.
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* If name is provided, removes only the named mark.
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* @param name
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*/
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clearMarks(name?: string): void;
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/**
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* Creates a new PerformanceMark entry in the Performance Timeline.
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* A PerformanceMark is a subclass of PerformanceEntry whose performanceEntry.entryType is always 'mark',
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* and whose performanceEntry.duration is always 0.
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* Performance marks are used to mark specific significant moments in the Performance Timeline.
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* @param name
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*/
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mark(name?: string, options?: MarkOptions): void;
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/**
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* Creates a new PerformanceMeasure entry in the Performance Timeline.
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* A PerformanceMeasure is a subclass of PerformanceEntry whose performanceEntry.entryType is always 'measure',
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* and whose performanceEntry.duration measures the number of milliseconds elapsed since startMark and endMark.
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*
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* The startMark argument may identify any existing PerformanceMark in the the Performance Timeline, or may identify
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* any of the timestamp properties provided by the PerformanceNodeTiming class. If the named startMark does not exist,
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* then startMark is set to timeOrigin by default.
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*
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* The endMark argument must identify any existing PerformanceMark in the the Performance Timeline or any of the timestamp
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* properties provided by the PerformanceNodeTiming class. If the named endMark does not exist, an error will be thrown.
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* @param name
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* @param startMark
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* @param endMark
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*/
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measure(name: string, startMark?: string, endMark?: string): void;
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measure(name: string, options: MeasureOptions): void;
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/**
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* An instance of the PerformanceNodeTiming class that provides performance metrics for specific Node.js operational milestones.
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*/
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readonly nodeTiming: PerformanceNodeTiming;
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/**
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* @return the current high resolution millisecond timestamp
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*/
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now(): number;
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/**
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* The timeOrigin specifies the high resolution millisecond timestamp from which all performance metric durations are measured.
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*/
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readonly timeOrigin: number;
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/**
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* Wraps a function within a new function that measures the running time of the wrapped function.
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* A PerformanceObserver must be subscribed to the 'function' event type in order for the timing details to be accessed.
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* @param fn
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*/
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timerify<T extends (...params: any[]) => any>(fn: T, options?: TimerifyOptions): T;
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/**
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* eventLoopUtilization is similar to CPU utilization except that it is calculated using high precision wall-clock time.
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* It represents the percentage of time the event loop has spent outside the event loop's event provider (e.g. epoll_wait).
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* No other CPU idle time is taken into consideration.
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*/
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eventLoopUtilization: EventLoopUtilityFunction;
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}
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interface PerformanceObserverEntryList {
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/**
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* Returns a list of `PerformanceEntry` objects in chronological order
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* with respect to `performanceEntry.startTime`.
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*
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* ```js
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* const {
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* performance,
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* PerformanceObserver
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* } = require('perf_hooks');
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*
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* const obs = new PerformanceObserver((perfObserverList, observer) => {
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* console.log(perfObserverList.getEntries());
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*
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* * [
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* * PerformanceEntry {
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* * name: 'test',
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* * entryType: 'mark',
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* * startTime: 81.465639,
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* * duration: 0
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* * },
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* * PerformanceEntry {
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* * name: 'meow',
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* * entryType: 'mark',
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* * startTime: 81.860064,
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* * duration: 0
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* * }
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* * ]
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*
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* observer.disconnect();
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* });
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* obs.observe({ type: 'mark' });
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*
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* performance.mark('test');
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* performance.mark('meow');
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* ```
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* @since v8.5.0
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*/
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getEntries(): PerformanceEntry[];
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/**
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* Returns a list of `PerformanceEntry` objects in chronological order
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* with respect to `performanceEntry.startTime` whose `performanceEntry.name` is
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* equal to `name`, and optionally, whose `performanceEntry.entryType` is equal to`type`.
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*
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* ```js
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* const {
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* performance,
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* PerformanceObserver
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* } = require('perf_hooks');
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*
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* const obs = new PerformanceObserver((perfObserverList, observer) => {
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* console.log(perfObserverList.getEntriesByName('meow'));
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*
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* * [
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* * PerformanceEntry {
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* * name: 'meow',
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* * entryType: 'mark',
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* * startTime: 98.545991,
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* * duration: 0
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* * }
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* * ]
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*
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* console.log(perfObserverList.getEntriesByName('nope')); // []
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*
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* console.log(perfObserverList.getEntriesByName('test', 'mark'));
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*
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* * [
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* * PerformanceEntry {
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* * name: 'test',
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* * entryType: 'mark',
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* * startTime: 63.518931,
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* * duration: 0
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* * }
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* * ]
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*
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* console.log(perfObserverList.getEntriesByName('test', 'measure')); // []
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* observer.disconnect();
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* });
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* obs.observe({ entryTypes: ['mark', 'measure'] });
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*
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* performance.mark('test');
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* performance.mark('meow');
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* ```
|
* @since v8.5.0
|
*/
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getEntriesByName(name: string, type?: EntryType): PerformanceEntry[];
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/**
|
* Returns a list of `PerformanceEntry` objects in chronological order
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* with respect to `performanceEntry.startTime` whose `performanceEntry.entryType`is equal to `type`.
|
*
|
* ```js
|
* const {
|
* performance,
|
* PerformanceObserver
|
* } = require('perf_hooks');
|
*
|
* const obs = new PerformanceObserver((perfObserverList, observer) => {
|
* console.log(perfObserverList.getEntriesByType('mark'));
|
*
|
* * [
|
* * PerformanceEntry {
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* * name: 'test',
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* * entryType: 'mark',
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* * startTime: 55.897834,
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* * duration: 0
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* * },
|
* * PerformanceEntry {
|
* * name: 'meow',
|
* * entryType: 'mark',
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* * startTime: 56.350146,
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* * duration: 0
|
* * }
|
* * ]
|
*
|
* observer.disconnect();
|
* });
|
* obs.observe({ type: 'mark' });
|
*
|
* performance.mark('test');
|
* performance.mark('meow');
|
* ```
|
* @since v8.5.0
|
*/
|
getEntriesByType(type: EntryType): PerformanceEntry[];
|
}
|
type PerformanceObserverCallback = (list: PerformanceObserverEntryList, observer: PerformanceObserver) => void;
|
class PerformanceObserver extends AsyncResource {
|
constructor(callback: PerformanceObserverCallback);
|
/**
|
* Disconnects the `PerformanceObserver` instance from all notifications.
|
* @since v8.5.0
|
*/
|
disconnect(): void;
|
/**
|
* Subscribes the `PerformanceObserver` instance to notifications of new `PerformanceEntry` instances identified either by `options.entryTypes`or `options.type`:
|
*
|
* ```js
|
* const {
|
* performance,
|
* PerformanceObserver
|
* } = require('perf_hooks');
|
*
|
* const obs = new PerformanceObserver((list, observer) => {
|
* // Called three times synchronously. `list` contains one item.
|
* });
|
* obs.observe({ type: 'mark' });
|
*
|
* for (let n = 0; n < 3; n++)
|
* performance.mark(`test${n}`);
|
* ```
|
* @since v8.5.0
|
*/
|
observe(
|
options:
|
| {
|
entryTypes: ReadonlyArray<EntryType>;
|
buffered?: boolean | undefined;
|
}
|
| {
|
type: EntryType;
|
buffered?: boolean | undefined;
|
}
|
): void;
|
}
|
namespace constants {
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const NODE_PERFORMANCE_GC_MAJOR: number;
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const NODE_PERFORMANCE_GC_MINOR: number;
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const NODE_PERFORMANCE_GC_INCREMENTAL: number;
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const NODE_PERFORMANCE_GC_WEAKCB: number;
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const NODE_PERFORMANCE_GC_FLAGS_NO: number;
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const NODE_PERFORMANCE_GC_FLAGS_CONSTRUCT_RETAINED: number;
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const NODE_PERFORMANCE_GC_FLAGS_FORCED: number;
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const NODE_PERFORMANCE_GC_FLAGS_SYNCHRONOUS_PHANTOM_PROCESSING: number;
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const NODE_PERFORMANCE_GC_FLAGS_ALL_AVAILABLE_GARBAGE: number;
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const NODE_PERFORMANCE_GC_FLAGS_ALL_EXTERNAL_MEMORY: number;
|
const NODE_PERFORMANCE_GC_FLAGS_SCHEDULE_IDLE: number;
|
}
|
const performance: Performance;
|
interface EventLoopMonitorOptions {
|
/**
|
* The sampling rate in milliseconds.
|
* Must be greater than zero.
|
* @default 10
|
*/
|
resolution?: number | undefined;
|
}
|
interface Histogram {
|
/**
|
* Returns a `Map` object detailing the accumulated percentile distribution.
|
* @since v11.10.0
|
*/
|
readonly percentiles: Map<number, number>;
|
/**
|
* The number of times the event loop delay exceeded the maximum 1 hour event
|
* loop delay threshold.
|
* @since v11.10.0
|
*/
|
readonly exceeds: number;
|
/**
|
* The minimum recorded event loop delay.
|
* @since v11.10.0
|
*/
|
readonly min: number;
|
/**
|
* The maximum recorded event loop delay.
|
* @since v11.10.0
|
*/
|
readonly max: number;
|
/**
|
* The mean of the recorded event loop delays.
|
* @since v11.10.0
|
*/
|
readonly mean: number;
|
/**
|
* The standard deviation of the recorded event loop delays.
|
* @since v11.10.0
|
*/
|
readonly stddev: number;
|
/**
|
* Resets the collected histogram data.
|
* @since v11.10.0
|
*/
|
reset(): void;
|
/**
|
* Returns the value at the given percentile.
|
* @since v11.10.0
|
* @param percentile A percentile value in the range (0, 100].
|
*/
|
percentile(percentile: number): number;
|
}
|
interface IntervalHistogram extends Histogram {
|
/**
|
* Enables the update interval timer. Returns `true` if the timer was
|
* started, `false` if it was already started.
|
* @since v11.10.0
|
*/
|
enable(): boolean;
|
/**
|
* Disables the update interval timer. Returns `true` if the timer was
|
* stopped, `false` if it was already stopped.
|
* @since v11.10.0
|
*/
|
disable(): boolean;
|
}
|
interface RecordableHistogram extends Histogram {
|
/**
|
* @since v15.9.0, v14.18.0
|
* @param val The amount to record in the histogram.
|
*/
|
record(val: number | bigint): void;
|
/**
|
* Calculates the amount of time (in nanoseconds) that has passed since the
|
* previous call to `recordDelta()` and records that amount in the histogram.
|
*
|
* ## Examples
|
* @since v15.9.0, v14.18.0
|
*/
|
recordDelta(): void;
|
}
|
/**
|
* _This property is an extension by Node.js. It is not available in Web browsers._
|
*
|
* Creates an `IntervalHistogram` object that samples and reports the event loop
|
* delay over time. The delays will be reported in nanoseconds.
|
*
|
* Using a timer to detect approximate event loop delay works because the
|
* execution of timers is tied specifically to the lifecycle of the libuv
|
* event loop. That is, a delay in the loop will cause a delay in the execution
|
* of the timer, and those delays are specifically what this API is intended to
|
* detect.
|
*
|
* ```js
|
* const { monitorEventLoopDelay } = require('perf_hooks');
|
* const h = monitorEventLoopDelay({ resolution: 20 });
|
* h.enable();
|
* // Do something.
|
* h.disable();
|
* console.log(h.min);
|
* console.log(h.max);
|
* console.log(h.mean);
|
* console.log(h.stddev);
|
* console.log(h.percentiles);
|
* console.log(h.percentile(50));
|
* console.log(h.percentile(99));
|
* ```
|
* @since v11.10.0
|
*/
|
function monitorEventLoopDelay(options?: EventLoopMonitorOptions): IntervalHistogram;
|
interface CreateHistogramOptions {
|
/**
|
* The minimum recordable value. Must be an integer value greater than 0.
|
* @default 1
|
*/
|
min?: number | bigint | undefined;
|
/**
|
* The maximum recordable value. Must be an integer value greater than min.
|
* @default Number.MAX_SAFE_INTEGER
|
*/
|
max?: number | bigint | undefined;
|
/**
|
* The number of accuracy digits. Must be a number between 1 and 5.
|
* @default 3
|
*/
|
figures?: number | undefined;
|
}
|
/**
|
* Returns a `RecordableHistogram`.
|
* @since v15.9.0, v14.18.0
|
*/
|
function createHistogram(options?: CreateHistogramOptions): RecordableHistogram;
|
}
|
declare module 'node:perf_hooks' {
|
export * from 'perf_hooks';
|
}
|
