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From: Jeff King <>
To: Junio C Hamano <>
Cc: Matt McCutchen <>, git <>
Subject: Re: Protecting old temporary objects being reused from concurrent "git gc"?
Date: Wed, 16 Nov 2016 03:07:54 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, Nov 15, 2016 at 12:01:35PM -0800, Junio C Hamano wrote:

> Jeff King <> writes:
> > I suspect the issue is that read-tree populates the cache-tree index
> > extension, and then write-tree omits the object write before it even
> > gets to write_sha1_file(). The solution is that it should probably be
> > calling one of the freshen() functions (possibly just replacing
> > has_sha1_file() with check_and_freshen(), but I haven't looked).
> I think the final writing always happens via write_sha1_file(), but
> an earlier cache-tree update that says "if we have a tree object
> already, then use it, otherwise even though we know the object name
> for this subtree, do not record it in the cache-tree" codepath may
> decide to record the subtree's sha1 without refreshing the referent.
> A fix may look like this.

Yeah, that's along the lines I was expecting, though I'm not familiar
enough with cache-tree to say whether it's sufficient. I notice there is
a return very early on in update_one() when has_sha1_file() matches, and
it seems like that would trigger in some interesting cases, too.


  reply	other threads:[~2016-11-16 17:18 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-15 14:13 Protecting old temporary objects being reused from concurrent "git gc"? Matt McCutchen
2016-11-15 17:06 ` Jeff King
2016-11-15 17:33   ` Matt McCutchen
2016-11-15 17:40     ` Jeff King
2016-11-15 19:08       ` [PATCH] git-gc.txt: expand discussion of races with other processes Matt McCutchen
2016-11-15 19:12       ` Protecting old temporary objects being reused from concurrent "git gc"? Matt McCutchen
2016-11-15 20:01       ` Junio C Hamano
2016-11-16  8:07         ` Jeff King [this message]
2016-11-16 18:18           ` Junio C Hamano
2016-11-16 18:58       ` Junio C Hamano
2016-11-17  1:04         ` Jeff King
2016-11-17  1:35           ` Re* " Junio C Hamano
2016-11-17  1:43             ` Jeff King

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