From: Eric Sunshine <firstname.lastname@example.org>
To: "Michal Suchánek" <email@example.com>
Cc: "Git List" <firstname.lastname@example.org>,
"Marketa Calabkova" <email@example.com>,
"Nguyễn Thái Ngọc Duy" <firstname.lastname@example.org>,
"Junio C Hamano" <email@example.com>
Subject: Re: [PATCH v3 2/2] setup: don't fail if commondir reference is deleted.
Date: Thu, 21 Feb 2019 04:27:21 -0500 [thread overview]
Message-ID: <CAPig+cT48d9JJyqVx0WvBiFV+BLqAqo5dX3yndNhoJZmKRPgEg@mail.gmail.com> (raw)
On Wed, Feb 20, 2019 at 1:35 PM Eric Sunshine <firstname.lastname@example.org> wrote:
> On Wed, Feb 20, 2019 at 12:16 PM Michal Suchánek <email@example.com> wrote:
> > On Wed, 20 Feb 2019 11:55:46 -0500
> > Eric Sunshine <firstname.lastname@example.org> wrote:
> > > On Wed, Feb 20, 2019 at 11:17 AM Michal Suchanek <email@example.com> wrote:
> > > > Another even rarer issue is that the file might be zero size because another
> > > > process initializing a worktree opened the file but has not written is content
> > > > yet.
> > >
> > > Based upon the explanation thus far, I'm having trouble understanding
> > > under what circumstances these race conditions can arise. Are you
> > > trying to invoke Git commands in a particular worktree even as the
> > > worktree itself is being created?
> > It's explained in the following paragraph. If you have multiple
> > worktrees some *other* worktreee may be uninitialized.
> I understand that, but setup.c:get_common_dir_noenv() is concerned
> only with _this_ worktree -- the one in which the Git command is being
> run -- so it's not clear if or how some other partially-initialized
> worktree could have any impact. (And, I'm having trouble fathoming how
> it could, which is why I'm asking these questions).
I still can't see how setup.c:get_common_dir_noenv() could be
responsible for the behavior you're describing of _any_ Git command
erroring out due to _any_ worktree being incompletely-initialized.
However, I can imagine "git worktree add" itself being racy and
failing due to a missing or empty "commondir" file for some other
worktree since that command _does_ consult other worktree entries when
validating the "add" operation via
builtin/worktree.c:validate_worktree_add() which calls
get_worktrees(). If get_worktrees() is subject to that raciness
problem, then "git worktree add" will inherit that undesirable
raciness behavior (as will other "git worktree" commands which call
get_worktrees(), such as "git worktree list").
> Is it possible that when you saw that error message, it actually arose
> from some code other than setup.c:get_common_dir_noenv()?
So, I'm suspecting get_worktrees() or some function it calls (and so
on) as the racy culprit.
next prev parent reply other threads:[~2019-02-21 9:27 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 17:04 [PATCH 0/2] worktree add race fix Michal Suchanek
2019-02-18 17:04 ` [PATCH 1/2] worktree: fix worktree add race Michal Suchanek
2019-02-18 17:04 ` [PATCH 2/2] setup: don't fail if commondir reference is deleted Michal Suchanek
2019-02-18 21:00 ` Eric Sunshine
2019-02-21 10:50 ` Duy Nguyen
2019-02-21 13:50 ` Michal Suchánek
2019-02-21 17:07 ` Phillip Wood
2019-02-21 17:12 ` Eric Sunshine
2019-02-21 17:27 ` Phillip Wood
2019-03-04 13:30 ` Michal Suchánek
2019-02-21 17:33 ` Michal Suchánek
2019-02-22 9:32 ` Duy Nguyen
2019-02-22 10:20 ` Phillip Wood
2019-02-22 9:26 ` Duy Nguyen
2019-02-20 16:16 ` [PATCH v3 1/2] worktree: fix worktree add race Michal Suchanek
2019-02-20 16:34 ` Eric Sunshine
2019-02-20 17:29 ` Michal Suchánek
2019-03-08 9:20 ` Duy Nguyen
2019-03-08 9:37 ` Eric Sunshine
2019-03-11 1:55 ` Junio C Hamano
2019-02-20 16:16 ` [PATCH v3 2/2] setup: don't fail if commondir reference is deleted Michal Suchanek
2019-02-20 16:55 ` Eric Sunshine
2019-02-20 17:16 ` Michal Suchánek
2019-02-20 18:35 ` Eric Sunshine
2019-02-21 9:27 ` Eric Sunshine [this message]
2019-02-21 11:13 ` Michal Suchánek
2019-02-21 11:19 ` Michal Suchánek
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