Re: [GSoC] Applying for conversion scripts to builtins

From: Junio C Hamano <gitster@pobox.com>
Date: Mar 17, 2015, 18:38 UTC
Message-ID: <xmqqpp87o4eo.fsf@gitster.dls.corp.google.com>
In-Reply-To: <4355599932558291b22313f244eda9bd@www.dscho.org>

Johannes Schindelin <johannes.schindelin@gmx.de> writes:

> Therefore, I would wager a bet that just the mere conversion of a
> shell script into even a primitive `run_command()`-based builtin would
> help performance on Windows in a noticeable manner.

As you correctly allege, if a patch rewrote a shell-scripted porcelain by using series of run_command() and doing nothing else, I would have asked "is that an improvement?", without knowing that.

> Of course, it would be *even nicer* to avoid the spawning altogether.

Yeah, that, too ;-)

Show 12 quoted lines

> The biggest benefit of avoiding needless parsing, however, is not
> performance. It is avoiding quoting issues. This is particularly so on
> Windows, where Git is sometimes called from outside a shell
> environment, where we have to deal with inconsistent quoting because
> it is every Windows program's own job to parse the command-line,
> including the quoting.
>
> Concrete example: on Windows, we have file locking issues because
> files that are in use cannot be deleted. For that reason, we have
> Windows-specific code that is "nice" by trying harder to delete files,
> giving programs a little time to let their locks go. This locking
> issue happens also when a virus scanner "uses"...

These are definitely good advices from the area expert.

Thanks for a bunch of good input.