Re: git auto-repack is broken...

On Fri, Dec 02, 2011 at 08:56:34AM -0800, Linus Torvalds wrote:

On Fri, Dec 2, 2011 at 8:27 AM, Ævar Arnfjörð Bjarmason
[off-list ref] wrote:

quoted

quoted

Maybe we should make "git gc --auto" remove any unreachable objects?

Wouldn't that mean that any loose commit objects you have lying around
would be removed by the automatic git gc?

One feature of git that I personally rely on is that I can liberally
move heads around / make commits on detached heads and not have those
commits gc'd unless I explicitly ask for it for a while.

Well, with reflogs, you actually do have those objects reachable for
quite a while (90 days by default).

The "unreachable objects" tends to happen when you do fetches without
ever merging the result or actually remove branches (and/or expiring
the reflogs early etc). Not from the normal "use 'git reset' and
friends to move heads around".

That said, I do agree that removing loose objects is the much less
safe approach.

We do remove loose objects that are totally unreferenced, but there is
still a time-delay, because we don't want to prune something like an
in-progress commit operation. The default delay for that is 2 weeks,
which I think is an arbitrary number that was "wow, if your git
operation takes longer than this, you're way too patient".

And in general, it works OK because people don't tend to accumulate more
than the auto-gc number of objects within a 2 week period. So perhaps
you're just special in your usage patterns.

One solution is just dropping that "2 weeks" down to something smaller,
but still conservative (say, 3 days?).

If you still have the repo in question, what is the date breakdown on
your loose objects?

Of course, repacking the objects results in problems too: now you've
entirely lost the age information for that object, so now you cannot
prune it based on age any more.

When the objects become unreferenced, we eject them from the pack into
loose form again. If they don't become referenced in the 2-week window,
they get pruned then. So yes, you drop the age information, but they do
eventually go away.

-Peff