From: Lars Schneider <larsxschneider@gmail.com>
To: Jeff King <peff@peff.net>
Cc: "Torsten Bögershausen" <tboegi@web.de>,
"Git Mailing List" <git@vger.kernel.org>,
"Junio C Hamano" <gitster@pobox.com>,
"Jakub Narębski" <jnareb@gmail.com>,
mlbright@gmail.com, remi.galan-alfonso@ensimag.grenoble-inp.fr,
pclouds@gmail.com, e@80x24.org, ramsay@ramsayjones.plus.com
Subject: Re: [PATCH v2 4/5] convert: generate large test files only once
Date: Wed, 27 Jul 2016 18:50:40 +0200 [thread overview]
Message-ID: <1D133FC4-032F-434A-882C-5931AA285CD9@gmail.com> (raw)
In-Reply-To: <20160727133214.GA14928@sigill.intra.peff.net>
> On 27 Jul 2016, at 15:32, Jeff King <peff@peff.net> wrote:
>
> On Wed, Jul 27, 2016 at 04:35:32AM +0200, Torsten Bögershausen wrote:
>
>>> + mkdir -p generated-test-data &&
>>> + for i in $(test_seq 1 $T0021_LARGE_FILE_SIZE)
>>> + do
>>> + # Generate 1MB of empty data and 100 bytes of random characters
>>> + printf "%1048576d" 1
>>> + printf "$(LC_ALL=C tr -dc "A-Za-z0-9" </dev/urandom | dd bs=$((RANDOM>>8)) count=1 2>/dev/null)"
>> I'm not sure how portable /dev/urandom is.
>> The other thing, that "really random" numbers are an overkill, and
>> it may be easier to use pre-defined numbers,
>
> Right, there are a few reasons not to use /dev/urandom:
>
> - it's not portable
>
> - if we have to generate a lot of numbers, it drains the system's
> entropy pool, which is an unfriendly thing to do (and may also be
> slow)
>
> - it makes our tests random! This sounds like a good thing, but it
> means that if some input happens to cause failure, you are unlikely
> to be able to reproduce it.
>
> Instead, use test-genrandom, which is an LCG that starts at a seed. So
> you get a large amount of random-ish quickly and portably, and you get
> the same data each time.
Thank you! That's exactly what I need here :-)
- Lars
next prev parent reply other threads:[~2016-07-27 16:50 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-22 15:48 [PATCH v1 0/3] Git filter protocol larsxschneider
2016-07-22 15:48 ` [PATCH v1 1/3] convert: quote filter names in error messages larsxschneider
2016-07-22 15:48 ` [PATCH v1 2/3] convert: modernize tests larsxschneider
2016-07-26 15:18 ` Remi Galan Alfonso
2016-07-26 20:40 ` Junio C Hamano
2016-07-22 15:49 ` [PATCH v1 3/3] convert: add filter.<driver>.useProtocol option larsxschneider
2016-07-22 22:32 ` Torsten Bögershausen
2016-07-24 12:09 ` Lars Schneider
2016-07-22 23:19 ` Ramsay Jones
2016-07-22 23:28 ` Ramsay Jones
2016-07-24 17:16 ` Lars Schneider
2016-07-24 22:36 ` Ramsay Jones
2016-07-24 23:22 ` Jakub Narębski
2016-07-25 20:32 ` Lars Schneider
2016-07-26 10:58 ` Jakub Narębski
2016-07-25 20:24 ` Lars Schneider
2016-07-23 0:11 ` Jakub Narębski
2016-07-23 7:27 ` Eric Wong
2016-07-26 20:00 ` Jeff King
2016-07-24 18:36 ` Lars Schneider
2016-07-24 20:14 ` Jakub Narębski
2016-07-24 21:30 ` Jakub Narębski
2016-07-25 20:16 ` Lars Schneider
2016-07-26 12:24 ` Jakub Narębski
2016-07-25 20:09 ` Lars Schneider
2016-07-26 14:18 ` Jakub Narębski
2016-07-23 8:14 ` Eric Wong
2016-07-24 19:11 ` Lars Schneider
2016-07-25 7:27 ` Eric Wong
2016-07-25 15:48 ` Duy Nguyen
2016-07-22 21:39 ` [PATCH v1 0/3] Git filter protocol Junio C Hamano
2016-07-24 11:24 ` Lars Schneider
2016-07-26 20:11 ` Jeff King
2016-07-27 0:06 ` [PATCH v2 0/5] " larsxschneider
2016-07-27 0:06 ` [PATCH v2 1/5] convert: quote filter names in error messages larsxschneider
2016-07-27 20:01 ` Jakub Narębski
2016-07-28 8:23 ` Lars Schneider
2016-07-27 0:06 ` [PATCH v2 2/5] convert: modernize tests larsxschneider
2016-07-27 0:06 ` [PATCH v2 3/5] pkt-line: extract and use `set_packet_header` function larsxschneider
2016-07-27 0:20 ` Junio C Hamano
2016-07-27 9:13 ` Lars Schneider
2016-07-27 16:31 ` Junio C Hamano
2016-07-27 0:06 ` [PATCH v2 4/5] convert: generate large test files only once larsxschneider
2016-07-27 2:35 ` Torsten Bögershausen
2016-07-27 13:32 ` Jeff King
2016-07-27 16:50 ` Lars Schneider [this message]
2016-07-27 0:06 ` [PATCH v2 5/5] convert: add filter.<driver>.process option larsxschneider
2016-07-27 1:32 ` Jeff King
2016-07-27 17:31 ` Lars Schneider
2016-07-27 18:11 ` Jeff King
2016-07-28 12:10 ` Lars Schneider
2016-07-28 13:35 ` Jeff King
2016-07-27 9:41 ` Eric Wong
2016-07-29 10:38 ` Lars Schneider
2016-07-29 11:24 ` Jakub Narębski
2016-07-29 11:31 ` Lars Schneider
2016-08-05 18:55 ` Eric Wong
2016-08-05 23:26 ` Lars Schneider
2016-08-05 23:38 ` Eric Wong
2016-07-27 23:31 ` Jakub Narębski
2016-07-29 8:04 ` Lars Schneider
2016-07-29 17:35 ` Junio C Hamano
2016-07-29 23:11 ` Jakub Narębski
2016-07-29 23:44 ` Lars Schneider
2016-07-30 9:32 ` Jakub Narębski
2016-07-28 10:32 ` Torsten Bögershausen
2016-07-27 19:08 ` [PATCH v2 0/5] Git filter protocol Jakub Narębski
2016-07-28 7:16 ` Lars Schneider
2016-07-28 10:42 ` Jakub Narębski
2016-07-28 13:29 ` Jeff King
2016-07-29 7:40 ` Jakub Narębski
2016-07-29 8:14 ` Lars Schneider
2016-07-29 15:57 ` Jeff King
2016-07-29 16:20 ` Lars Schneider
2016-07-29 16:50 ` Jeff King
2016-07-29 17:43 ` Lars Schneider
2016-07-29 18:27 ` Jeff King
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