const { MongoClient } = require('mongodb');
async function main(pid) {
  const client = new MongoClient('mongodb://localhost:27017/', { useNewUrlParser: true, useUnifiedTopology: true });
  await client.connect()

  const collection = client.db().collection('test');
  await collection.insertOne({ a: 42 });
  for (let counter = 0; counter < 100000; counter++) {
    collection.insertOne({ a: 42 }, _ => {});
  }

  await client.close();
}

main().catch(console.error);