[fishnchips]

> since it uses lock files on S3 versus a separate DyanamoDB + S3 combo

This is disturbing because S3 does not give you guarantees required to implement real locking.

[erik_seaberg]

https://aws.amazon.com/blogs/aws/amazon-s3-update-strong-rea... guarantees that a client's lockfile can always be seen by other clients immediately (which didn't used to be true). If every client backs off and retries after a race, is that enough?

[fishnchips]

I think not, actually. There would still be cases where a race is not detected. I can think of the following sequence: A checks - no lock, B checks - no lock, A writes - success, A reads - match, success, B writes - success, B reads - match, success. A and B both think they now hold the lock.

For locking to work properly you'd need to have a conditional write that would fail if some prerequisite was not met. GCP offers that operation, S3 AFAIK does not.