Re: Make the git codebase thread-safe

From: Stefan Zager <szager@google.com>
Date: Feb 15, 2014, 00:50 UTC
Message-ID: <CAHOQ7J-gGbnADQ+3TGy6b6LJSLH8jvAbdTrc20Ybh=p0D2FmsQ@mail.gmail.com>
In-Reply-To: <CACsJy8Dzj5iyaUseNyU76ojG1C0VYR=v7xsc=6TSGxTh=Xh3Ag@mail.gmail.com>

On Fri, Feb 14, 2014 at 4:45 PM, Duy Nguyen <pclouds@gmail.com> wrote:

Show 17 quoted lines

> On Sat, Feb 15, 2014 at 2:16 AM, Zachary Turner <zturner@chromium.org> wrote:
>> (Gah, sorry if you're receiving multiple emails to your personal
>> addresses, I need to get used to manually setting Plain-text mode
>> every time I send a message).
>>
>> For the mixed read, we wouldn't be looking for another caller of
>> pread() (since it doesn't care what the file pointer is), but instead
>> a caller of read() or lseek() (since those do depend on the current
>> file pointer).  In index-pack.c, I see two possible culprits:
>>
>> 1) A call to xread() from inside fill()
>> 2) A call to lseek in parse_pack_objects()
>>
>> Do you think these could be related?  If so, maybe that opens up some
>> other solutions?
>
> For index-pack alone, what's wrong with open one file handle per thread?

Nothing wrong with that, except that it would mean either using thread-local storage (which the code doesn't currently use); or plumbing pack_fd through the call stack, which doesn't sound very fun.

Stefan

> --
> Duy