Re: Multiple fetches when unshallowing a shallow clone

From: Jeff King <peff@peff.net>
Date: Dec 4, 2015, 22:10 UTC
Message-ID: <20151204221009.GA23129@sigill.intra.peff.net>
In-Reply-To: <xmqqoae5ri5x.fsf@gitster.mtv.corp.google.com>

On Fri, Dec 04, 2015 at 01:57:30PM -0800, Junio C Hamano wrote:

Show 30 quoted lines

> Jeff King <peff@peff.net> writes:
> 
> > This seems to reproduce consistently for me:
> >
> >   $ git clone --depth=1 git://github.com/git/git
> >   Cloning into 'git'...
> >   remote: Counting objects: 2925, done.
> >   remote: Compressing objects: 100% (2602/2602), done.
> >   remote: Total 2925 (delta 230), reused 2329 (delta 206), pack-reused 0
> >   Receiving objects: 100% (2925/2925), 6.17 MiB | 10.80 MiB/s, done.
> >   Resolving deltas: 100% (230/230), done.
> >
> >   $ cd git
> >   $ git fetch --unshallow
> >   remote: Counting objects: 185430, done.
> >   remote: Compressing objects: 100% (46933/46933), done.
> >   remote: Total 185430 (delta 140505), reused 181589 (delta 136694), pack-reused 0
> >   Receiving objects: 100% (185430/185430), 52.80 MiB | 10.84 MiB/s, done.
> >   Resolving deltas: 100% (140505/140505), completed with 1784 local objects.
> >   remote: Counting objects: 579, done.
> >   remote: Compressing objects: 100% (579/579), done.
> >   remote: Total 579 (delta 0), reused 579 (delta 0), pack-reused 0
> >   Receiving objects: 100% (579/579), 266.85 KiB | 0 bytes/s, done.
> >   [... fetch output ...]
> >
> > That looks like two packs being received for the --unshallow case.
> 
> What is puzzling is that I do not seem to see this "two fetches"
> with the local transport.  I only see "deepen 2147483647" in the
> protocol log.

Yeah, I do not ever see "deepen 0" from GIT_TRACE_PACKET output. FWIW, here's the output I am using to reproduce this locally:

  # do this once
  git clone --bare git://github.com/git/git src.git

  # do this for each test run
  rm -rf repo
  git clone --no-local --depth=1 src.git repo
  cd repo
  echo "==> unshallow" &&
  git fetch --progress --unshallow 2>&1 | grep remote

And you can see that there are two separate sections (and I traced this to backfill_tags() with gdb).

Note that the issue goes away if the shallow clone is done with "--bare" (I guess because we pick up tags differently in the initial clone?).

-Peff