mongoose: eachAsync with async function causes memory leak

Do you want to request a feature or report a bug? Bug

What is the current behavior? When iterating on a query cursor with eachAsync and an async function as callback the memory quickly grows until the node app crashes.

If the current behavior is a bug, please provide the steps to reproduce. No memory leak:

const playerCursor: QueryCursor<IPlayerProfileModel> = PlayerProfile.find({}, projection).lean().cursor();
    await playerCursor.eachAsync(
      (profile: IPlayerProfileModel) => {
        return;
      },
      { parallel: 50 }
    );

Memory leak:

const playerCursor: QueryCursor<IPlayerProfileModel> = PlayerProfile.find({}, projection).lean().cursor();
    await playerCursor.eachAsync(
      async (profile: IPlayerProfileModel) => {
        return;
      },
      { parallel: 50 }
    );

What is the expected behavior?

Iteration on cursor, with max 50 async functions running concurrently without having a memory leak. The same issue appears with a concurrency of 1 (the memory just grows way slower then).

Please mention your node.js, mongoose and MongoDB version. Node 8.2.1, Mongoose 4.13.5 MongoDb 3.4