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From: Eric Sunshine <sunshine@sunshineco.com>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: Jeff King <peff@peff.net>, Eric Wong <e@80x24.org>,
	Eric Sunshine via GitGitGadget <gitgitgadget@gmail.com>,
	Git List <git@vger.kernel.org>, Elijah Newren <newren@gmail.com>,
	Fabian Stelzer <fs@gigacodes.de>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH 06/18] chainlint.pl: validate test scripts in parallel
Date: Mon, 21 Nov 2022 09:07:33 -0500	[thread overview]
Message-ID: <CAPig+cS3Ui=SFuRLPKKugT9RFvtUV3FmO23Wse_Rhih5hgbPmg@mail.gmail.com> (raw)
In-Reply-To: <221121.86tu2sbfh8.gmgdl@evledraar.gmail.com>

On Mon, Nov 21, 2022 at 8:32 AM Ævar Arnfjörð Bjarmason
<avarab@gmail.com> wrote:
> On Sun, Nov 20 2022, Eric Sunshine wrote:
> > Somehow Windows manages to be unbelievably slow no matter what. I
> > mentioned elsewhere (after you sent this) that I tested on a five or
> > six year old 8-core dual-boot machine. Booted to Linux, running a
> > single chainlint.pl invocation using all 8 cores to check all scripts
> > in the project took under 1 second walltime. The same machine booted
> > to Windows using all 8 cores took just under two minutes(!) walltime
> > for the single Perl invocation to check all scripts in the project.
>
> I'd be really interested in seeing e.g. the NYTProf output for that run,
> compared with that on *nix (if you could upload the HTML versions of
> both somewhere, even better).

Unfortunately, I no longer have access to that machine, or usable
Windows in general. Of course, someone else with access to a dual-boot
machine could generate such a report, but whether anyone will offer to
do so is a different matter.

> Maybe "chainlint.pl" is doing something odd, but this goes against the
> usual wisdom about what is and isn't slow in Perl on windows, as I
> understand it.
>
> I.e. process star-up etc. is slow there, and I/O's a bit slower, but
> once you're started up and e.g. slurping up all of those files & parsing
> them you're just running "perl-native" code.
>
> Which shouldn't be much slower at all. A perl compiled with ithreads is
> (last I checked) around 10-20% slower, and the Windows version is always
> compiled with that (it's needed for "fork" emulation).
>
> But most *nix versions are compiled with that too, and certainly the one
> you're using with "threads", so that's not the difference.
>
> So I suspect something odd's going on...

This is all my understanding, as well, which is why I was so surprised
by the difference in speed. Aside from suspecting Windows I/O as the
culprit, another obvious possible culprit would be whatever
mechanism/primitives "ithreads" is using on Windows for
locking/synchronizing and passing messages between threads. I wouldn't
be surprised to learn that those mechanisms/primitives have very high
overhead on that platform.

> > Overall, I think Ævar's plan to parallelize linting via "make" is
> > probably the way to go.
>
> Yeah, but that seems to me to be orthagonal to why it's this slow on
> Windows, and if it is that wouldn't help much, except for incremental
> re-runs.

Oh, I didn't at all mean that `make` parallelism would be helpful on
Windows; I can't imagine that it ever would be (though I could once
again be wrong). What I meant was that `make` parallelism would be a
nice improvement and simplification (of sorts), in general,
considering that I've given up hope of ever seeing linting be speedy
on Windows.

  reply	other threads:[~2022-11-21 14:11 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-01  0:29 [PATCH 00/18] make test "linting" more comprehensive Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 01/18] t: add skeleton chainlint.pl Eric Sunshine via GitGitGadget
2022-09-01 12:27   ` Ævar Arnfjörð Bjarmason
2022-09-02 18:53     ` Eric Sunshine
2022-09-01  0:29 ` [PATCH 02/18] chainlint.pl: add POSIX shell lexical analyzer Eric Sunshine via GitGitGadget
2022-09-01 12:32   ` Ævar Arnfjörð Bjarmason
2022-09-03  6:00     ` Eric Sunshine
2022-09-01  0:29 ` [PATCH 03/18] chainlint.pl: add POSIX shell parser Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 04/18] chainlint.pl: add parser to validate tests Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 05/18] chainlint.pl: add parser to identify test definitions Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 06/18] chainlint.pl: validate test scripts in parallel Eric Sunshine via GitGitGadget
2022-09-01 12:36   ` Ævar Arnfjörð Bjarmason
2022-09-03  7:51     ` Eric Sunshine
2022-09-06 22:35   ` Eric Wong
2022-09-06 22:52     ` Eric Sunshine
2022-09-06 23:26       ` Jeff King
2022-11-21  4:02         ` Eric Sunshine
2022-11-21 13:28           ` Ævar Arnfjörð Bjarmason
2022-11-21 14:07             ` Eric Sunshine [this message]
2022-11-21 14:18               ` Ævar Arnfjörð Bjarmason
2022-11-21 14:48                 ` Eric Sunshine
2022-11-21 18:04           ` Jeff King
2022-11-21 18:47             ` Eric Sunshine
2022-11-21 18:50               ` Eric Sunshine
2022-11-21 18:52               ` Jeff King
2022-11-21 19:00                 ` Eric Sunshine
2022-11-21 19:28                   ` Jeff King
2022-11-22  0:11                   ` Ævar Arnfjörð Bjarmason
2022-09-01  0:29 ` [PATCH 07/18] chainlint.pl: don't require `return|exit|continue` to end with `&&` Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 08/18] t/Makefile: apply chainlint.pl to existing self-tests Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 09/18] chainlint.pl: don't require `&` background command to end with `&&` Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 10/18] chainlint.pl: don't flag broken &&-chain if `$?` handled explicitly Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 11/18] chainlint.pl: don't flag broken &&-chain if failure indicated explicitly Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 12/18] chainlint.pl: complain about loops lacking explicit failure handling Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 13/18] chainlint.pl: allow `|| echo` to signal failure upstream of a pipe Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 14/18] t/chainlint: add more chainlint.pl self-tests Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 15/18] test-lib: retire "lint harder" optimization hack Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 16/18] test-lib: replace chainlint.sed with chainlint.pl Eric Sunshine via GitGitGadget
2022-09-03  5:07   ` Elijah Newren
2022-09-03  5:24     ` Eric Sunshine
2022-09-01  0:29 ` [PATCH 17/18] t/Makefile: teach `make test` and `make prove` to run chainlint.pl Eric Sunshine via GitGitGadget
2022-09-01  0:29 ` [PATCH 18/18] t: retire unused chainlint.sed Eric Sunshine via GitGitGadget
2022-09-02 12:42   ` several messages Johannes Schindelin
2022-09-02 18:16     ` Eric Sunshine
2022-09-02 18:34       ` Jeff King
2022-09-02 18:44         ` Junio C Hamano
2022-09-11  5:28 ` [PATCH 00/18] make test "linting" more comprehensive Jeff King
2022-09-11  7:01   ` Eric Sunshine
2022-09-11 18:31     ` Jeff King
2022-09-12 23:17       ` Eric Sunshine
2022-09-13  0:04         ` Jeff King

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