When multiple clients push to same remote repository, how does git deal with concurrency issues?

Question

For each http request, a separate process git-http-backend runs on the server side.

When multiple clients push to same remote repository, what does it d

Answer 1

In the same manner as if invoked via SSH -- see the update_ref function in refs.c. The actual implementation of the locking mechanism lives in the lock_file function in lockfile.c, and yes, it creates a .lock file in there. Under the hood, it's done via the O_EXCL option to open().