Re: [PATCH v5 5/5] builtin/merge-tree.c: implement support for `--write-pack`

From: Jeff King <peff@peff.net>
Date: Nov 13, 2023, 22:05 UTC
Message-ID: <20231113220546.GB2065691@coredump.intra.peff.net>
In-Reply-To: <ZU7X3N/rqCK/Y9cj@nand.local>

On Fri, Nov 10, 2023 at 08:24:44PM -0500, Taylor Blau wrote:

Show 9 quoted lines

> > This does mean that for a recursive merge, that you'll get up to 2*N
> > packfiles, where N is the depth of the recursive merge.
> 
> We definitely want to avoid that ;-). I think there are a couple of
> potential directions forward here, but the most promising one I think is
> due to Johannes who suggests that we write loose objects into a
> temporary directory with a replace_tmp_objdir() call, and then repack
> that side directory before migrating a single pack back into the main
> object store.

I posted an alternative in response to Elijah; the general idea being to allow the usual object-lookup code to access the in-progress pack. That would keep us limited to a single pack.

It _might_ be a terrible idea. E.g., if you write a non-bulk object that references a bulk one, then that non-bulk one is broken from the perspective of other processes (until the bulk checkin is flushed). But I think we'd always be writing to one or the other here, never interleaving?

-Peff