nodejs: memory leak in `Impit` instance constructor

[barjin]

Each Impit instantiation takes up a constant amount of RSS, which is (seemingly) never freed.

import { Impit } from 'impit';

for (let i = 0; i < 30000; i++) {
  const impit = new Impit();

  if (i % 100 === 0) {
    console.log(process.memoryUsage().rss);
  }
}

The expected behaviour should be constant memory usage, as the Impit instances from previous iterations are unreachable and should get GCed.

[janbuchar]

Do you have any evidence of GC being run in your benchmark?

[barjin]

Sorry for the incomplete graph, Node's GC only manages V8's internal heap - GC is happening there, see the following charts (jagged yellow line, better visible in the logarithmic view).

Native Node addons will allocate their memory outside of V8's heap, but still in the process' resident set (all this is opaque from the OS's POV). That's why the RSS will grow in case of a memleak in a native addon.