Re: What's cooking in git.git (Apr 2014, #03; Fri, 11)

> On Tue, Apr 15, 2014 at 11:45 PM, Junio C Hamano <gitster@pobox.com> wrote:
>> Ramsay Jones <ramsay@ramsay1.demon.co.uk> 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.