Re: Slow git pushes: sitting 1 minute in pack-objects

From: Jeff King <peff@peff.net>
Date: Mar 9, 2015, 07:53 UTC
Message-ID: <20150309075302.GB31866@peff.net>
In-Reply-To: <CAH8BJxH1uVv9J7yLx1D4GRPKfWYqDw8SRFZKGR_yhjcoTCCT2g@mail.gmail.com>

On Thu, Mar 05, 2015 at 04:03:07PM -0500, Stephen Morton wrote:

> I'm experiencing very slow git pushes. On the order of 1 minute to push a
> trivial one-line change. When I set GIT_TRACE=1, I see that it seems to be
> taking a lot of time in the pack-objects phase.

Can you tell what pack-objects is doing? Perhaps "strace -f -tt" might help. Or even just "time git push", which will tell us whether we're spinning on CPU or something else.

If you watch the progress meter, where does it spend its time? In "counting objects", "compressing objects", or "writing objects"? Or after that?

You said the repo is big. Is it reasonably packed (try running `git gc`). Pack-objects may look at objects that you know the other side has in order to create deltas against them. If you have some crazy situation (e.g., you have several thousand packfiles) that can slow down object access quite a bit. A minute is more than I would expect, but if VFS operations in your VM are slow, that could be it.

-Peff