Re: Git rebase dies with fatal: Unable to create '.../.git/index.lock': File exists.

[Jason Gunthorpe <jgunthorpe@obsidianresearch.com>]

On Mon, Sep 16, 2013 at 05:15:01PM -0400, Jeff King wrote:
> On Mon, Sep 16, 2013 at 12:28:52PM -0600, Jason Gunthorpe wrote:
> 
> > I have emacs windows open that have files within the git tree open in
> > them. My emacs has vc-git mode loaded and global-auto-revert-mode set.
> > 
> > During the rebase the files open in emacs are changed by git, when
> > emacs notices this (which is random with respect to the ongoing
> > rebase) it auto reverts and runs git commands (due to vc-git), which
> > causes the rebase to randomly fail.
> > 
> > Worse, I've noticed that this also randomly seems to cause the rebase
> > to loose a commit if you --continue from that point.
> > 
> > Can git have some retry in the locking so this doesn't happen?
> 
> I'm not clear on which git commands are being run. If they are actually
> mutating the index, then isn't this more than a lock contention issue?
> In other words, "git rebase" is assuming nobody is mucking with the
> index while it runs; if emacs is doing so, then the results could be
> quite confusing, even if we retried the lock acquisition.

I'm not sure what commands vc-git mode in Emacs is actually running
automatically, but I'd be surprised and alaramed if they were mutating
command..

I agree retry on the lock is hackish, holding the lock continuously
rather than release/reaquire during operation would be much stronger
prevention.

Jason