Basic profiler for your node scripts

README.md

Basic profiler for your node scripts

Usage

import "./profile.js"

// do some stuff...
const items = [...new Array(100)].map((x, i) => i)
for (let i of items) {
    setTimeout(() => console.log(`item ${i}`), 150)
}

Output

$ node run.js
[...]
item 98
item 99

mem(total): 21.36MB	mem(init): 20.71MB	mem(alloc): 0.65MB
time: 164.065ms
samples: 3 interval: 100

Notes

By default, the script will sample every 100ms. You can change this with an environment variable:

$ PROFILE_INTERVAL=20 node run.js
[...]
item 98
item 99

mem(total): 21.35MB	mem(init): 20.66MB	mem(alloc): 0.70MB
time: 167.898ms
samples: 9 interval: 20

profile.js

console.time("time")
const PROFILE_INTERVAL = parseInt(process.env.PROFILE_INTERVAL || "100")
const base = process.memoryUsage().rss
let rss = 0
let countSamples = 0
const sample = () => {
    let memUsage = process.memoryUsage()
    if (memUsage.rss > rss) {
        rss = memUsage.rss
    }
    countSamples++
    setTimeout(sample, PROFILE_INTERVAL).unref()
}
sample()

process.on("exit", () => {
    sample()
    const imem = (base / 1000000).toFixed(2)
    const tmem = (rss / 1000000).toFixed(2)
    const amem = ((rss - base) / 1000000).toFixed(2)
    console.info(
        `\nmem(total): ${tmem}MB\tmem(init): ${imem}MB\tmem(alloc): ${amem}MB`
    )
    console.timeEnd("time")
    console.info(`samples: ${countSamples} interval: ${PROFILE_INTERVAL}`)
})