README.md

node-performance-emitter

A tool for collecting, aggregating, and emitting Node.js performance stats.

Collects stats on the event loop lag, garbage collection events, and memory statistics.

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Table of contents

• Installation
• Usage
• Setup
• API
  • Registration API
    • NodePerformanceEmitter
    • NodePerformanceEmitterToken
  • Dependencies
    • UniversalEventsToken
    • TimersToken
    • EventLoopLagIntervalToken
    • SocketIntervalToken
  • Events

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Installation

yarn add fusion-plugin-node-performance-emitter

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Usage

// src/performance-logging.js
import {createPlugin} from 'fusion-core';
import {UniversalEventsToken} from 'fusion-plugin-universal-events';

export default createPlugin({
  deps: { emitter: UniversalEventsToken },
  provides: deps => {
    const emitter = deps.emitter;
    emitter.on('node-performance-emitter:{action}', e => {
      console.log(e); // log events to console
    });
  }
});

---

Setup

// src/main.js
import App from 'fusion-core';
import NodePerformanceEmitter, {
  NodePerformanceEmitterToken,
  TimersToken,
  EventLoopLagIntervalToken,
  MemoryIntervalToken,
  SocketIntervalToken
} from 'fusion-plugin-node-performance-emitter';
import UniversalEvents, {UniversalEventsToken} from 'fusion-plugin-universal-events';

export default function() {
  const app = new App(...);

  app.register(UniversalEventsToken, UniversalEvents);
  if (__NODE__) {
    app.register(TimersToken, {setInterval, clearInterval}); // optional
    app.register(EventLoopLagIntervalToken, 10000); // optional
    app.register(MemoryIntervalToken, 10000); // optional
    app.register(SocketIntervalToken, 10000); // optional
    app.register(NodePerformanceEmitterToken, NodePerformanceEmitter);
  }

return app;
}

---

API

Registration API

NodePerformanceEmitter

import NodePerformanceEmitter from 'fusion-plugin-node-performance-emitter';

The plugin. Should typically be registered to NodePerformanceEmitterToken.

NodePerformanceEmitterToken

import {NodePerformanceEmitterToken} from 'fusion-plugin-node-performance-emitter';

Typically should be registered with NodePerformanceEmitter

Dependencies

UniversalEventsToken

Required. See https://github.com/fusionjs/fusion-plugin-universal-events

TimersToken

import {TimersToken} from 'fusion-plugin-node-performance-emitter';

Optional. Server-only. Register a setInterval/clearInterval implementation. Defaults to the global timer functions. Useful for testing.

Types

type Timers = {
  setInterval: (Function, number) => number,
  clearInterval: (number) => void,
}

EventLoopLagIntervalToken

import {EventLoopLagIntervalToken} from 'fusion-plugin-node-performance-emitter';

Optional. Server-only. The interval between event loop lag measurements. Defaults to 10000.

MemoryIntervalToken

import {MemoryIntervalToken} from 'fusion-plugin-node-performance-emitter';

Optional. Server-only. The interval between memory measurements. Defaults to 10000.

SocketIntervalToken

import {SocketIntervalToken} from 'fusion-plugin-node-performance-emitter';

Optional. Server-only. The interval between event socket usage measurements. Defaults to 10000.

Events

This package has no public API methods. To consume performance events, add an event listener for one of the following events:

• node-performance-emitter:gauge:event_loop_lag
• node-performance-emitter:gauge:rss- process.memoryUsage().rss
• node-performance-emitter:gauge:externalMemory - process.memoryUsage().external
• node-performance-emitter:gauge:heapTotal - process.memoryUsage().heapTotal
• node-performance-emitter:gauge:heapUsed - process.memoryUsage().heapUsed
• node-performance-emitter:timing:gc - time spent doing garbage collection
• node-performance-emitter:gauge:globalAgentSockets - http.globalAgent.sockets
• node-performance-emitter:gauge:globalAgentRequests- http.globalAgent.requests
• node-performance-emitter:gauge:globalAgentFreeSockets- http.globalAgent.freeSockets