Arvados

To be able to reliably use the fuse mount as a writable shared drive, it is necessary to be able to have multiple writers safely update the collection record.

Currently, there is a race condition whereby one writer may read the collection record, a 2nd writer writes an updated record, then the first writer writes a merged record which is loses the changes from the 2nd writer.

The solution is one of:

1) Implement conditional update of the database record based on PDH or timestamp; in the above scenario, the 2nd write would fail, get the updated record, re-merge and re-write

2) Implement a "merge" method on the API server which takes a list of changes and applies it to the manifest on the server to get a merged manifest.