On 16/04/14 00:18, Duy Nguyen wrote:
> On Tue, Apr 15, 2014 at 11:45 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
>> Ramsay Jones <ramsay@xxxxxxxxxxxxxxxxxxx> writes:
>>
>>> On 11/04/14 23:22, Junio C Hamano wrote:
>>> [...]
>>>> [New Topics]
>>>>
>>>> * nd/index-pack-one-fd-per-thread (2014-04-09) 1 commit
>>>> - index-pack: work around thread-unsafe pread()
>>>>
>>>> Enable threaded index-pack on platforms without thread-unsafe
>>>> pread() emulation.
>>>>
>>>> Will merge to 'next' and keep it there for the remainder of the cycle.
>>>
>>> The commit message for commit 512ebe5d ("index-pack: work around
>>> thread-unsafe pread()", 25-03-2014) is a little misleading.
>>
>> OK. Can we have a concrete alternative?
>>
>> Multi-threaing of index-pack was disabled with c0f8654
>> (index-pack: Disable threading on cygwin - 2012-06-26), because
>> pread() implementations for Cygwin and MSYS were not thread
>> safe. Recent Cygwin does offer usable pread() and we enabled
>> multi-threading with 103d530f (Cygwin 1.7 has thread-safe pread,
>> 2013-07-19).
>>
>> Work around this problem on platforms with a thread-unsafe
>> pread() emulation by opening one file handle per thread; it
>> would prevent parallel pread() on different file handles from
>> stepping on each other.
>>
>> Also remove NO_THREAD_SAFE_PREAD that was introduced in c0f8654
>> because it's no longer used anywhere.
>>
>> This workaround is unconditional, even for platforms with
>> thread-safe pread() because the overhead is small (a couple file
>> handles more) and not worth fragmenting the code.
>>
>
> OK to me.
Yep, this looks good to me too.
Thanks!
ATB,
Ramsay Jones
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