Depends on D19247. Ref T13109. When we receive an SSH request, generate a random unique ID for the request. Then thread it down through the process tree.
The immediate goal is to let the ssh-exec process coordinate with commit-hook process and log information about read and write lock wait times. Today, there's no way for ssh-exec to interact with the PushEvent, but this is the most helpful place to store this data for users.