def _batched_insert(self, objs, fields, batch_size):
        if not objs:
            return
        ops = connections[self.db].ops
        batch_size = (batch_size or max(ops.bulk_batch_size(fields, objs), 1))
        for batch in [objs[i:i+batch_size]
                      for i in range(0, len(objs), batch_size)]:
            self.model._base_manager._insert(batch, fields=fields,
                                             using=self.db)
A little helper method for bulk_insert to insert the bulk one batch
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/db/models/query.py/QuerySet._batched_insert