内存高效地将大型文件从S3传输到谷歌云存储

I have some working code below to transfer a file from S3 to Google Cloud Storage (GCS). From my understanding, this downloads the file into memory before uploading to GCS. I would like to find a more efficient way of doing this (in code). I realise Google has a transfer service and there are CLI options, but those aren't suitable for what I am doing.I have some working code below to transfer a fi