Maximum number of entries in Node.js Map?

Question

I was making a large Map in Node.js v11.9.0 and it kept failing with \"FATAL ERROR: invalid table size Allocation failed - JavaScript heap out of memory\". My map\'s keys an

Answer 1

What's interesting is if you change your code to create two Map objects and insert into them simultaneously, they both crash at exactly the same point, 16.7:

var N = Math.pow(2, 26);
var m1 = new Map();
var m2 = new Map();

for (var i = 0; i < N; i++) {
  m2.set(i, i + 1);
  m1.set(i, i + 1);

  if (i % 1e5 === 0) { console.log(m1.size / 1e6); }
}

There's something odd happening here when more than 2²⁴ entries are made in any given Map, not globally across all Map objects.

I think you've found a V8 bug that needs to be reported.