reasonable to publish thousands of different events on an EventEmitter? (benchmarks added) #4030
Closed as not planned
Description
Details
Is it reasonable to use EventEmitter for publishing hundreds or thousands of different events to consumers, or is necessary to broadcast such events through another mechanism. Pre-existing performance benchmarks weren't found.
Following the benchmark guide, and a comment from someone in the PR linked below, I've made the following benchmark script but am not certain how to interpret the results --it would seem using "only" tens of event emitters is a terrible idea. Would someone with benchmark or EventEmitter experience confirm this interpretation?
benchmark script, with results as follows below
const bench = common.createBenchmark(data => {
const ee = new EventEmitter();
ee.setMaxListeners(Infinity);
const listeners = [];
for (let k = 0; k < 10; k += 1)
listeners.push(() => {});
const eventNames = [];
for (let k = 0; k < data.events; ++k)
eventNames.push(`dummy${k}`);
// listen, emit then remove n events
bench.start();
for (let i = 0; i < data.n; i += 1) {
for (const eventName of eventNames) {
for (let k = listeners.length; k--;)
ee.on(eventName, listeners[k]);
}
for (const eventName of eventNames) {
for (let k = listeners.length; k--;)
ee.emit(eventName, data);
}
for (const eventName of eventNames) {
for (let k = listeners.length; k--;)
ee.removeListener(eventName, listeners[k]);
}
}
bench.end(data.n);
}, {
events: [ 6, ...Array.from(Array(16).keys()).slice(1).map(n => n * 10) ],
n: [10]
});t-emitter-benchmarks.js n=10 events=6: 6,518.042266896884
t-emitter-benchmarks.js n=10 events=10: 3,229.8886140612553
t-emitter-benchmarks.js n=10 events=20: 1,635.3395569995967
t-emitter-benchmarks.js n=10 events=30: 1,412.2709967272033
t-emitter-benchmarks.js n=10 events=40: 1,185.9759763962315
t-emitter-benchmarks.js n=10 events=50: 1,118.3136724470437
t-emitter-benchmarks.js n=10 events=60: 937.9777237794424
t-emitter-benchmarks.js n=10 events=70: 919.3701358424538
t-emitter-benchmarks.js n=10 events=80: 853.8230224669013
t-emitter-benchmarks.js n=10 events=90: 811.9099393771205
t-emitter-benchmarks.js n=10 events=100: 726.7387460689794
t-emitter-benchmarks.js n=10 events=110: 676.583211480697
t-emitter-benchmarks.js n=10 events=120: 700.618744437963
t-emitter-benchmarks.js n=10 events=130: 676.4745555595994
t-emitter-benchmarks.js n=10 events=140: 660.326519578054
t-emitter-benchmarks.js n=10 events=150: 623.2406306522083Node.js version
node 16 latest
Example code
const emitter = new events.EventEmitter()
events.on(emitter, 'one.of.thousands.of.uniquely.named.events')Operating system
alpine linux
Scope
runtime
Module and version
Not applicable.