def _do_batched_insert(collection_name, docs, check_keys,
                       safe, last_error_args, continue_on_error, opts,
                       ctx):
    """Insert `docs` using multiple batches.
    """
    def _insert_message(insert_message, send_safe):
        """Build the insert message with header and GLE.
        """
        request_id, final_message = __pack_message(2002, insert_message)
        if send_safe:
            request_id, error_message, _ = __last_error(collection_name,
                                                        last_error_args)
            final_message += error_message
        return request_id, final_message

    send_safe = safe or not continue_on_error
    last_error = None
    data = StringIO()
    data.write(struct.pack("<i", int(continue_on_error)))
    data.write(_make_c_string(collection_name))
    message_length = begin_loc = data.tell()
    has_docs = False
    to_send = []
    encode = _dict_to_bson  # Make local
    compress = ctx.compress and not (safe or send_safe)
    for doc in docs:
        encoded = encode(doc, check_keys, opts)
        encoded_length = len(encoded)
        too_large = (encoded_length > ctx.max_bson_size)

        message_length += encoded_length
        if message_length < ctx.max_message_size and not too_large:
            data.write(encoded)
            to_send.append(doc)
            has_docs = True
            continue

        if has_docs:
            # We have enough data, send this message.
            try:
                if compress:
                    rid, msg = None, data.getvalue()
                else:
                    rid, msg = _insert_message(data.getvalue(), send_safe)
                ctx.legacy_bulk_insert(
                    rid, msg, 0, send_safe, to_send, compress)
            # Exception type could be OperationFailure or a subtype
            # (e.g. DuplicateKeyError)
            except OperationFailure as exc:
                # Like it says, continue on error...
                if continue_on_error:
                    # Store exception details to re-raise after the final batch.
                    last_error = exc
                # With unacknowledged writes just return at the first error.
                elif not safe:
                    return
                # With acknowledged writes raise immediately.
                else:
                    raise

        if too_large:
            _raise_document_too_large(
                "insert", encoded_length, ctx.max_bson_size)

        message_length = begin_loc + encoded_length
        data.seek(begin_loc)
        data.truncate()
        data.write(encoded)
        to_send = [doc]

    if not has_docs:
        raise InvalidOperation("cannot do an empty bulk insert")

    if compress:
        request_id, msg = None, data.getvalue()
    else:
        request_id, msg = _insert_message(data.getvalue(), safe)
    ctx.legacy_bulk_insert(request_id, msg, 0, safe, to_send, compress)

    # Re-raise any exception stored due to continue_on_error
    if last_error is not None:
        raise last_error
Insert `docs` using multiple batches.