From: Stefan Beller <sbeller@google.com>
To: Jacob Keller <jacob.keller@gmail.com>
Cc: Johannes Sixt <j6t@kdbg.org>, Junio C Hamano <gitster@pobox.com>,
Git mailing list <git@vger.kernel.org>,
Brandon Williams <bmwill@google.com>
Subject: Re: [PATCHv2] attr: convert to new threadsafe API
Date: Wed, 12 Oct 2016 14:47:17 -0700 [thread overview]
Message-ID: <CAGZ79ka5qkDri0gCCLQQcUgqFpOi=np+jm-x046Foc9NOpE6NA@mail.gmail.com> (raw)
In-Reply-To: <CA+P7+xqBUT3jUsxciVydO+nRoR+iJygWG=y_ARpiQSs+-kcH2A@mail.gmail.com>
On Wed, Oct 12, 2016 at 2:45 PM, Jacob Keller <jacob.keller@gmail.com> wrote:
> On Wed, Oct 12, 2016 at 1:07 PM, Johannes Sixt <j6t@kdbg.org> wrote:
>>
>> Sigh. DCLP, the Double Checked Locking Pattern. These days, it should be
>> common knowledge among professionals that this naïve version _does_not_work_
>> [1]!
>>
>> I suggest you go without it, then measure, and only *then* optimize if it is
>> a bottleneck. Did I read "we do not expect much contention" somewhere?
>>
>> [1] http://www.aristeia.com/Papers/DDJ_Jul_Aug_2004_revised.pdf C++ centric,
>> but applies to C just as well
>>
>> -- Hannes
>>
>
>
> You know, I always wondered why Linux Kernel code needed memory
> barriers but userspace programs didn't seem to use them.. turns out
> they actually *do* need them for the same exact types of problems...
>
> Thanks,
> Jake
In a former job I made use of them, too. So I am kinda embarrassed.
(I cannot claim I did not know about these patterns and memory
fencing, it just escaped my consciousness).
next prev parent reply other threads:[~2016-10-12 22:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-11 23:59 [PATCHv2] attr: convert to new threadsafe API Stefan Beller
2016-10-12 6:12 ` Junio C Hamano
2016-10-12 6:51 ` Stefan Beller
2016-10-12 16:20 ` Junio C Hamano
2016-10-12 20:02 ` Stefan Beller
2016-10-12 20:59 ` Junio C Hamano
2016-10-12 22:57 ` Junio C Hamano
2016-10-12 20:07 ` Johannes Sixt
2016-10-12 21:38 ` Junio C Hamano
2016-10-12 21:42 ` Stefan Beller
2016-10-12 21:50 ` Junio C Hamano
2016-10-12 21:45 ` Jacob Keller
2016-10-12 21:47 ` Stefan Beller [this message]
2016-10-12 21:28 ` Junio C Hamano
2016-10-12 21:39 ` Stefan Beller
2016-10-12 21:44 ` Junio C Hamano
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