From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 30 Jul 2013 15:39:48 GMT
Subject: Re: [PATCH] sha1_file: introduce close_one_pack() to close packs on fd pressure
Message-ID: <7v61vsxdiz.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1375157113-608-1-git-send-email-bcasey@nvidia.com>

Brandon Casey <bcasey@nvidia.com> writes:

> From: Brandon Casey <drafnel@gmail.com>
>
> When the number of open packs exceeds pack_max_fds, unuse_one_window()
> is called repeatedly to attempt to release the least-recently-used
> pack windows, which, as a side-effect, will also close a pack file
> after closing its last open window.  If a pack file has been opened,
> but no windows have been allocated into it, it will never be selected
> by unuse_one_window() and hence its file descriptor will not be
> closed.  When this happens, git may exceed the number of file
> descriptors permitted by the system.

An interesting find.  The patch from a cursory look reads OK.

Thanks.

> This is not likely to occur during upload-pack since upload-pack
> reads each object from the pack so that it can peel tags and
> advertise the exposed object.

Another interesting find.  Perhaps there is a room for improvements,
as packed-refs file knows what objects the tags peel to?  I vaguely
recall Peff was actively reducing the object access during ref
enumeration in not so distant past...