On Wed, Nov 30, 2016 at 04:15:33PM -0800, Steven Noonan wrote:
> It seems like it's behaving as though I've provided
> --pack-kept-objects. In order to ensure the .bitmap is created, it
> repacks everything, including everything in existing .pack files (not
> respecting .keep). But then it's not deleting the old .pack file
> (oddly, respecting .keep).
Right, that's exactly what's happening.
The bitmaps require a completely reachable set inside the pack, so if
you omit some objects that are in .keep packs, we cannot generate the
bitmap. So we have to either disable bitmaps, or pack the kept objects.
By default, we do the latter (and I'll explain why in a minute).
We can't delete the .keep packfiles because we don't know for sure that
we've included all of their contents in the new pack (not to mention
that somebody asked to keep them, and we don't know why; we should
respect that).
> What I'd expect it to do here is ignore the 'repack.writeBitmaps =
> true' value if there's a .keep that needs to be respected. Is this not
> a correct assumption?
In practice, I think that ends up worse. The .keep files are used by
receive-pack as lockfiles for incoming pushes. So imagine you kick off a
full repack just as somebody is pushing, and repack sees the temporary
.keep file. Your options are:
1. Disable bitmaps, leaving the repository with no bitmaps at all
until the next repack (because you're deleting the old bitmaps
along with the old, non-kept pack).
2. Duplicate the newly pushed objects in the pack (if they're even
reachable; you're also racing to see the ref updates). Now you have
bitmaps, but you're wasting a bit of space to store the racy push
twice (and it goes away next time you repack).
If you're running a Git server which depends on bitmaps for good
performance, then (2) is much better. And that's the default.
If you want to override it, you can pass --no-pack-kept-objects, or set
repack.packKeptObjects to false.
I think the documentation for --pack-kept-objects could be a bit more
clear for this case. It doesn't mention the default value, nor that what
you really want with "-b" is probably "--no-pack-kept-objects".
-Peff