From: Junio C Hamano Date: Mon, 11 May 2026 02:32:33 GMT Subject: Re: [PATCH] config: retry acquiring config.lock for 100ms Message-ID: In-Reply-To: Patrick Steinhardt writes: >> This bites in practice when running `git worktree add -b` concurrently >> against the same repository. Each invocation makes several writes to >> ".git/config" to set up branch tracking, and tooling that creates >> worktrees in parallel sees intermittent failures. Worse, `git worktree >> add` does not propagate the failed config write to its exit code: the >> worktree is created and the command exits 0, but tracking >> configuration is silently dropped. > > This very much sounds like a bug that is worth fixing independently. > >> The lock is held only for the duration of rewriting a small file, so >> retrying for 100 ms papers over any realistic contention while still >> failing fast if a stale lock has been left behind by a crashed >> process. This mirrors what we already do for individual reference >> locks (4ff0f01cb7 (refs: retry acquiring reference locks for 100ms, >> 2017-08-21)). > > Famous last words :) Experience tells me that any timeout value that > isn't excessive will eventually be hit in some production system. Which > raises the question whether we want to make the timeout configurable, > similar to "core.filesRefLockTimeout" and "core.packedRefsTimeout". > ... > Honestly though, I'm not really sure what to make with this. We could > of course also add some validation that the configuration we want to set > hasn't been modified meanwhile. But that would now lead to a situation > where we have to update every single caller in our tree to make use of > the new mechanism, which would be a bunch of work. > > And adding the timeout doesn't really change the status quo, either. We > already have the case that we'll happily overwrite changes made by > concurrent processes. The only thing that changes is that we make it > more likely for concurrent changes to succeed. We haven't heard any response to these points raised in the message I am responding to. Should I still keep the patch in my tree, hoping that a responses may come some day? I am tempted to discard the topic as it has been quite a while since we last looked at it. Thanks.