def init_multipart_upload(self):
    res = self.s3_client.create_multipart_upload(
        Bucket=DESTINATION_BUCKET,
        Key=MULTIPART_UPLOAD_FILE_NAME
    )
    print ("文件 {} 初始化分片上传 upload_id {}".format(MULTIPART_UPLOAD_FILE, res["UploadId"]))
    return res["UploadId"]