TypeScript Bits

Avoid using ts-node when performance testing

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Estimated reading time : 2 minutes

Often times when performance testing, or comparing resource utilization (ex NodeJS vs Java), I have seen developers load testing (even one off testing) with ts-node. ts-node is an awesome piece of kit, but it is for rapid prototyping, watching, and development only, it is not a production runtime.

When performance testing, even one offs, use tsc my-nodejs-app.ts && node my-node-app

Simple test sample

const numberArray : Array<number> = [2,6,1,9,0,5,8,7,3,4];
numberArray.sort();
const heapUsed = Math.round((process.memoryUsage().heapUsed / (1024*1024)));
const cpuTime = Math.round((process.cpuUsage().user / 1000));
console.log(`Approximately ${heapUsed}MB and ${cpuTime}ms of CPU time was used by this process.`);

Using ts-node

Approximately 61MB and 1466ms of CPU time was used by this process.

Using tsc index.ts && node index

Approximately 2MB and 25ms of CPU time was used by this process.

Notes

heapUsed is the actual memory used during the execution of a Node process
memoryUsage provides rss, heapTotal, heapUsed, external, arrayBuffers metrics as well
the command NODE_ENV=production tsc index.ts && node index will ensure that your one off test mimics your production environment build and runtime
this is an illustration, not an accurate representation of resource usage
- an APM + a performance test with sustained load over time will provide the most accurate information

A great article that discusses NodeJS profiling here..