Re: [PATCH 0/3] Another approach to large transactions

From: Stefan Beller <sbeller@google.com>
To: Jeff King <peff@peff.net>
Cc: Junio C Hamano <gitster@pobox.com>,
	Michael Haggerty <mhagger@alum.mit.edu>,
	"git@vger.kernel.org" <git@vger.kernel.org>
Subject: Re: [PATCH 0/3] Another approach to large transactions
Date: Wed, 22 Apr 2015 12:14:08 -0700	[thread overview]
Message-ID: <CAGZ79kY_1JqKBiAL14me8ktqdQMJ1UuTy1_MgBY4jy5i_qX0uA@mail.gmail.com> (raw)
In-Reply-To: <20150421232112.GA28316@peff.net>

On Tue, Apr 21, 2015 at 4:21 PM, Jeff King <peff@peff.net> wrote:
> On Mon, Apr 20, 2015 at 05:31:11PM -0700, Stefan Beller wrote:
>
>> When running the test locally, i.e. not in the test suite, but typing
>> the commands
>> myself into the shell, Git is fine with having just 5 file descriptors left.
>> The additional 4 required fds come from beign run inside the test suite.
>>
>> When strace-ing git, I cannot see any possible other fds which would require
>> having some left over space required. So I'd propose we'd just take a reasonable
>> number not too small for various test setups like 32 and then go with the
>> proposed patches.
>
> FWIW, we already use a magic value of "25 extra" in open_packed_git_1. I
> don't know if that means the number has been proven in practice, or if
> it is simply that nobody actually exercises the pack_max_fds code. I
> suspect it is the latter, especially since d131b7a (sha1_file.c: Don't
> retain open fds on small packs, 2011-03-02).

25 is equally sound as I could not find any hard calculation on that
number in the
history or code. I will change it to 25 in the next version of the patch.

Thanks!
Stefan