code: function proceedWithBackup() {
      if (options.resume) {
        // pick up from existing log file from previous run
        downloadRemainingBatches(options.log, db, ee, start, batchesPerDownloadSession, options.parallelism);
      } else {
        // create new log file and process
        spoolchanges(db, options.log, options.bufferSize, ee, function(err) {
          if (err) {
            ee.emit('error', err);
          } else {
            downloadRemainingBatches(options.log, db, ee, start, batchesPerDownloadSession, options.parallelism);
          }
        });
      }
    }
docs: max batches to read from log file for download at a time (prevent OOM)