[31438] in Perl-Users-Digest
Perl-Users Digest, Issue: 2690 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Nov 24 06:09:38 2009
Date: Tue, 24 Nov 2009 03:09:06 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Tue, 24 Nov 2009 Volume: 11 Number: 2690
Today's topics:
Re: access pref. and temp dir on windows <dontmewithme@got.it>
Re: access pref. and temp dir on windows <bart.lateur@pandora.be>
Re: perl hash: low-level implementation details? <isaacyho@gmail.com>
Re: perl hash: low-level implementation details? <jurgenex@hotmail.com>
Re: perl hash: low-level implementation details? <uri@StemSystems.com>
Re: perl hash: low-level implementation details? <nospam-abuse@ilyaz.org>
Re: perl hash: low-level implementation details? <xemoth@gmail.com>
Re: perl hash: low-level implementation details? <xhoster@gmail.com>
Re: perl hash: low-level implementation details? <xhoster@gmail.com>
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@seesig.invalid
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Tue, 24 Nov 2009 00:32:25 +0100
From: "Larry" <dontmewithme@got.it>
Subject: Re: access pref. and temp dir on windows
Message-Id: <4b0b1b88$0$34595$4fafbaef@reader1.news.tin.it>
"Ben Morrow" <ben@morrow.me.uk> ha scritto nel messaggio
news:j11rt6-uvt1.ln1@osiris.mauzo.dyndns.org...
>
> File::HomeDir->my_data returns what on a default XP install would be
> called
>
> C:\Documents and Settings\<user>\Local Settings\Application Data
>
> and you can retrieve the non-Local Settings path with
great! that's what I was looking for
------------------------------
Date: Tue, 24 Nov 2009 11:15:35 +0100
From: Bart Lateur <bart.lateur@pandora.be>
Subject: Re: access pref. and temp dir on windows
Message-Id: <mbcng55te9k5812k1mq544njl5287lg6vb@4ax.com>
Larry wrote:
>I am so sorry...I meant to say: where are those directories on windows?
See File::Temp and File::HomeDir on CPAN.
Less portable, it might not even work on somebody else's PC, is to use
some data available in the environment variables, see %ENV (perlvar).
--
Bart.
------------------------------
Date: Mon, 23 Nov 2009 15:31:57 -0800 (PST)
From: zikester <isaacyho@gmail.com>
Subject: Re: perl hash: low-level implementation details?
Message-Id: <efef806a-ca2b-4005-b73d-e18cede9d2d6@r24g2000prf.googlegroups.com>
On Nov 23, 2:58=A0pm, "Uri Guttman" <u...@StemSystems.com> wrote:
> >>>>> "z" =3D=3D zikester =A0<isaac...@gmail.com> writes:
>
> =A0 z> On Nov 23, 1:56=A0pm, J=FCrgen Exner <jurge...@hotmail.com> wrote:
> =A0 >> zikester <isaac...@gmail.com> wrote:
> =A0 >> >I've written a perl program that takes 3GB worth of key/value pai=
rs
> =A0 >> >( each are numbers in the range of 0-60million ), and builds a ha=
sh
> =A0 >> >with them. =A0The hash itself seems to be taking more than 130GB =
( linux
> =A0 >> >64-bit ) and counting--I had to kill the program b/c it was growi=
ng
> =A0 >> >too large ( we have some 130Gb memory machines at our lab ).
> =A0 >>
> =A0 >> >Is there an article/book that describes the inner workings of per=
l
> =A0 >> >data structures / hashes in particular? =A0 I just want to know w=
hy it's
> =A0 >> >taking so much memory.
> =A0 >>
> =A0 >> One wild guess: the keys in a hash are always strings. I.e. even i=
f you
> =A0 >> use numbers Perl will use the string value of that number, not the
> =A0 >> numerical value itself. Depending on the minimum size of a string =
in
> =A0 >> perl this could add up quickly. How many key-value pairs are we ta=
lking
> =A0 >> about?
> =A0 >>
> =A0 >> Implementing a sparse array may be a better choice (is there a mod=
ule
> =A0 >> for that?).
> =A0 >>
> =A0 >> jue
>
> =A0 z> Good point--we are talking about 510 million pairs of data. =A0I
> =A0 z> actually did reimplement this in C++ using a sparse array of vecto=
rs
> =A0 z> and it ran in about 15Gb.
>
> =A0 z> And good guess as to the hash value always being strings: =A0is th=
ere
> =A0 z> any documentation on the low-level workings on these types of topi=
cs?
> =A0 z> I'd love to get more in-depth knowledge of what Perl is actually d=
oing
> =A0 z> at the "C" level.
>
> hashes take up space for the key in string form and an SV for the
> value and other overhead. you can check out the space usage with the
> Devel::Size module.
>
> since your numbers are all under 60M you can save some space by using a
> packed 4 byte integer for the key instead of the stringified number
> which can be up to 8 bytes long. this may not actually save any space
> since the allocated string buffer will likely hold 8 bytes anyhow but it
> is worth trying out. easy to check this out with devel::size on a small
> data set.
>
> and it would be very easy to make your own sparse matrix (i found
> Math::MatrixSparse cpan but i don't know how efficient it is and it is
> version .01). just write a simple hash for your numbers and index (mod
> the array size) into a large array. handle collisions with one of
> several easy algorithms (rehash until no collision, sequential scan for
> next empty slot, or push to an array for that slot). that should lower
> your storage needs by quite a bit as arrays use less ram than hashes.
>
> if you are really tightfisted about space, you can even implement that
> whole thing in a single (very large) scalar string. that will have
> almost no perl overhead but you will need to use substr to index into
> the slots (of your making) and deal with collisions and buckets (that
> holds the actual value of a key). this isn't too hard but could be worth
> it if you need the space.
>
> finally, why aren't you using a disk based hash like some dbm flavor?
> many exist and are pretty fast and do caching for speed. then the code
> is just a tied hash and you no extra work. slower for sure than ram but
> if you have lots of ram, it can do the job in decent time.
>
> uri
>
> --
> Uri Guttman =A0------ =A0u...@stemsystems.com =A0-------- =A0http://www.s=
ysarch.com--
> ----- =A0Perl Code Review , Architecture, Development, Training, Support =
------
> --------- =A0Gourmet Hot Cocoa Mix =A0---- =A0http://bestfriendscocoa.com=
---------
Thanks for the alternate approaches: I realize the impracticality of
my approach, but I just want to understand what is going on :)
The following simplified code generates 16Gb of RAM usage for me.
Since we have 50 million pairs, given a hash of size 50 million slots
we get about 320 bytes of memory usage per slot. Each slot on average
would have close to 1 member in it, so I don't think the string
explanation accounts for all of the memusage. I've heard strings
have a base overhead of a few dozen bytes ( i.e., a string of length 1
would still cost about 40 bytes ). If this is so, then perhaps the
fact that the keys and values are both strings ( 80 bytes ), the fact
that the hash may allocate more slots than it needs so as to avoid
collisions to keep the density around 50% ( x factor of 2 =3D160
bytes ), and the linked lists could be implemented as vectors which
themselves over allocate by a factor of 2 so as to reduce the need for
expensive mallocs() ( =3D320 bytes ), then maybe the usage isn't so far
fetched.
I will look into Devel::size right now
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
use strict;
# simulate generating pairs
my %hash =3D ();
$|=3D1;
my $maxId =3D 60000000;
my $numPairs =3D 50000000;
for ( my $i=3D0; $i < $numPairs; $i++ )
{
if ( $i % 10000 =3D=3D 0 ) { print "." };
my $key =3D rand() * $maxId;
my $value =3D $key;
if ( exists( $hash{ $key } ) )
{
push( @{$hash{ $key } }, $value );
}
else
{
$hash{ $key } =3D [ $value ];
}
------------------------------
Date: Mon, 23 Nov 2009 15:44:01 -0800
From: Jürgen Exner <jurgenex@hotmail.com>
Subject: Re: perl hash: low-level implementation details?
Message-Id: <ja7mg5lcgha841f3k859j3p11v1jlt9a33@4ax.com>
zikester <isaacyho@gmail.com> wrote:
>On Nov 23, 1:56 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
>> zikester <isaac...@gmail.com> wrote:
>> >Is there an article/book that describes the inner workings of perl
>> >data structures / hashes in particular? I just want to know why it's
>> >taking so much memory.
>>
>> One wild guess: the keys in a hash are always strings. I.e. even if you
>> use numbers Perl will use the string value of that number, not the
>> numerical value itself. Depending on the minimum size of a string in
>> perl this could add up quickly. How many key-value pairs are we talking
>> about?
>>
>> Implementing a sparse array may be a better choice (is there a module
>> for that?).
>>
>> jue
>
>Good point--we are talking about 510 million pairs of data. I
>actually did reimplement this in C++ using a sparse array of vectors
>and it ran in about 15Gb.
>
>And good guess as to the hash value always being strings:
NO!!!! The key is a string, the value can be any scalar!
jue
------------------------------
Date: Mon, 23 Nov 2009 19:16:11 -0500
From: "Uri Guttman" <uri@StemSystems.com>
Subject: Re: perl hash: low-level implementation details?
Message-Id: <87ws1gzsj8.fsf@quad.sysarch.com>
>>>>> "z" == zikester <isaacyho@gmail.com> writes:
z> ===============================================
z> use strict;
add use warnings!
z> # simulate generating pairs
z> my %hash = ();
no need to initialize a hash to the emtpy list. my does that for you.
z> $|=1;
z> my $maxId = 60000000;
z> my $numPairs = 50000000;
z> for ( my $i=0; $i < $numPairs; $i++ )
for my $i ( 1 .. $numPairs ) {
recent perls will optimize that to a loop and not build the full list.
z> {
z> if ( $i % 10000 == 0 ) { print "." };
z> my $key = rand() * $maxId;
that is more commonly done as rand( $maxid ). it generates the same
results.
z> my $value = $key;
z> if ( exists( $hash{ $key } ) )
z> {
z> push( @{$hash{ $key } }, $value );
z> }
z> else
z> {
z> $hash{ $key } = [ $value ];
z> }
bah! you don't know about autovivification! the push line on its own
will work find. perl will make an anon array for you when it sees an
undef used as a reference. i wrote this years ago and post it here on a
semiregular basis. go read it!
http://sysarch.com/Perl/autoviv.txt
that whole bottom part could just be:
my $key = rand( $maxid )
push( @{$hash{ $key } }, $key );
uri
--
Uri Guttman ------ uri@stemsystems.com -------- http://www.sysarch.com --
----- Perl Code Review , Architecture, Development, Training, Support ------
--------- Gourmet Hot Cocoa Mix ---- http://bestfriendscocoa.com ---------
------------------------------
Date: Tue, 24 Nov 2009 04:40:35 +0000 (UTC)
From: Ilya Zakharevich <nospam-abuse@ilyaz.org>
Subject: Re: perl hash: low-level implementation details?
Message-Id: <slrnhgmou2.ng8.nospam-abuse@powdermilk.math.berkeley.edu>
On 2009-11-23, zikester <isaacyho@gmail.com> wrote:
> I've written a perl program that takes 3GB worth of key/value pairs
> ( each are numbers in the range of 0-60million ), and builds a hash
> with them. The hash itself seems to be taking more than 130GB ( linux
> 64-bit ) and counting--I had to kill the program b/c it was growing
> too large ( we have some 130Gb memory machines at our lab ).
>
> Is there an article/book that describes the inner workings of perl
> data structures / hashes in particular? I just want to know why it's
> taking so much memory.
I suspect your Perl may be broken. The typical overhead is below 100B
per key (on 32-bit machines) + extra malloc overhead. So 5e8 keys
should not take more than 500M * 200B = 100GB overhead on a 64-bit
machine.
Did you try to use "my" malloc when you configured Perl?
Ilya
------------------------------
Date: Mon, 23 Nov 2009 20:55:40 -0800 (PST)
From: Owen <xemoth@gmail.com>
Subject: Re: perl hash: low-level implementation details?
Message-Id: <018b8540-5ebb-4d7d-92b2-af5b3cf7c610@u16g2000pru.googlegroups.com>
On Nov 24, 11:16=A0am, "Uri Guttman" <u...@StemSystems.com> wrote:
> >>>>> "z" =3D=3D zikester =A0<isaac...@gmail.com> writes:
>
> =A0 z> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> =A0 z> use strict;
>
> add use warnings!
>
> =A0 z> # simulate generating pairs
>
> =A0 z> my %hash =3D ();
>
> no need to initialize a hash to the emtpy list. my does that for you.
>
> =A0 z> $|=3D1;
>
> =A0 z> my $maxId =3D 60000000;
> =A0 z> my $numPairs =3D 50000000;
> =A0 z> for ( my $i=3D0; $i < $numPairs; $i++ )
>
> for my $i ( 1 .. $numPairs ) {
>
> recent perls will optimize that to a loop and not build the full list.
>
> =A0 z> {
> =A0 z> =A0 =A0 if ( $i % 10000 =3D=3D 0 ) { print "." };
> =A0 z> =A0 =A0 my $key =3D rand() * $maxId;
>
> that is more commonly done as rand( $maxid ). it generates the same
> results.
>
> =A0 z> =A0 =A0 my $value =3D $key;
>
> =A0 z> =A0 =A0 if ( exists( $hash{ $key } ) )
> =A0 z> =A0 =A0 {
> =A0 z> =A0 =A0 =A0 =A0 push( @{$hash{ $key } }, $value );
> =A0 z> =A0 =A0 }
> =A0 z> =A0 =A0 else
> =A0 z> =A0 =A0 {
> =A0 z> =A0 =A0 =A0 =A0 $hash{ $key } =3D [ $value ];
> =A0 z> =A0 =A0 }
>
> bah! you don't know about autovivification! the push line on its own
> will work find. perl will make an anon array for you when it sees an
> undef used as a reference. i wrote this years ago and post it here on a
> semiregular basis. go read it!
>
> =A0 =A0 =A0 =A0http://sysarch.com/Perl/autoviv.txt
>
> that whole bottom part could just be:
>
> =A0 =A0 =A0 =A0 my $key =3D rand( $maxid )
> =A0 =A0 =A0 =A0 push( @{$hash{ $key } }, $key );
>
> uri
>
> --
> Uri Guttman =A0------ =A0u...@stemsystems.com =A0-------- =A0http://www.s=
ysarch.com--
> ----- =A0Perl Code Review , Architecture, Development, Training, Support =
------
> --------- =A0Gourmet Hot Cocoa Mix =A0---- =A0http://bestfriendscocoa.com=
---------
So I tried all that, with $numPairs =3D 500000, and watching htop, it
took 100 MB of memory. With the number increased tenfold to 5000000,
memory usage went to 1000 MB. My conclusion 200 MB per million pairs,
or 100 GB for 500 million pairs
#!/usr/bin/perl
use strict;
use warnings;
my %hash;
$| =3D 1;
my $maxId =3D 60000000;
my $numPairs =3D 500000;
for my $i ( 1 .. $numPairs ) {
my $key =3D rand($maxId);
push( @{ $hash{$key} }, $key );
}
Owen
------------------------------
Date: Mon, 23 Nov 2009 20:35:06 -0800
From: Xho Jingleheimerschmidt <xhoster@gmail.com>
Subject: Re: perl hash: low-level implementation details?
Message-Id: <4b0b6ec5$0$2866$ed362ca5@nr5-q3a.newsreader.com>
zikester wrote:
>> zikester <isaac...@gmail.com> wrote:
>>> I've written a perl program that takes 3GB worth of key/value pairs
>>> ( each are numbers in the range of 0-60million ),
...
> Good point--we are talking about 510 million pairs of data.
3GB/510 million pairs/ 2 things per pair = less than 3 bytes per number.
You can't store up to 60 million using only 3 bytes.
Also, you can't have 510 million distinct keys in the range of 0-60
million, unless you are talking floats. How are you dealing with
duplicated keys?
>>> and builds a hash
>>> with them. The hash itself seems to be taking more than 130GB ( linux
>>> 64-bit ) and counting--I had to kill the program b/c it was growing
>>> too large ( we have some 130Gb memory machines at our lab ).
>>> Is there an article/book that describes the inner workings of perl
>>> data structures / hashes in particular? I just want to know why it's
>>> taking so much memory.
That is what Perl does--throw memory at every possible problem.
> And good guess as to the hash value always being strings: is there
> any documentation on the low-level workings on these types of topics?
I don't think there is. The philosophy seems to be:
1) If you have to ask, Perl might not be the right tool for this
particular problem.
2) Use the source, Luke.
> I'd love to get more in-depth knowledge of what Perl is actually doing
> at the "C" level.
Perl is open source. You can't get much closer to the C level than the
actual C.
Xho
------------------------------
Date: Mon, 23 Nov 2009 21:23:14 -0800
From: Xho Jingleheimerschmidt <xhoster@gmail.com>
Subject: Re: perl hash: low-level implementation details?
Message-Id: <4b0b6ec7$0$2866$ed362ca5@nr5-q3a.newsreader.com>
zikester wrote:
>
> Thanks for the alternate approaches: I realize the impracticality of
> my approach, but I just want to understand what is going on :)
>
>
> The following simplified code generates 16Gb of RAM usage for me.
> Since we have 50 million pairs, given a hash of size 50 million slots
> we get about 320 bytes of memory usage per slot. Each slot on average
> would have close to 1 member in it,
Each value slot will have exactly one value in it--that is how Perl
hashes work. However, in you code that value will be a reference to an
array, which array will on average have close to 1 element in it.
And there goes your memory. You have about 50 million tiny arrays, each
one using a lot of overhead.
I'd guess roughly it comes up to something like: 48 bytes for the key
and associated structure, 40 bytes for the value-scalar (which holds an
arrayref), 160 bytes for the array overhead, and 48 bytes for each
scalar (usually 1) inside each array.
> so I don't think the string
> explanation accounts for all of the memusage. I've heard strings
> have a base overhead of a few dozen bytes ( i.e., a string of length 1
> would still cost about 40 bytes ).
On 64 bit machine, I think this is pretty close.
> If this is so, then perhaps the
> fact that the keys and values are both strings ( 80 bytes ), the fact
> that the hash may allocate more slots than it needs so as to avoid
> collisions to keep the density around 50% ( x factor of 2 =160
> bytes ),
But it doesn't work like that. I think an unused hash slot is only the
size of a pointer. The slot itself doesn't have the storage for the key
or the value (and if it did, how would it know the size of your future
key and/or value?)
Xho
------------------------------
Date: Tue, 24 Nov 2009 02:13:02 -0600
From: tadmc@seesig.invalid
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.9 $)
Message-Id: <hvKdnQFfJ9cTCJbWnZ2dnUVZ_o2dnZ2d@giganews.com>
Outline
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Must
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-----------------------------------------------------------------
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lot of very poor Perl books and web sites, and several good ones
too, of course.
Posting to comp.lang.perl.misc
There can be 200 messages in clpmisc in a single day. Nobody is going to
read every article. They must decide somehow which articles they are
going to read, and which they will skip.
Your post is in competition with 199 other posts. You need to "win"
before a person who can help you will even read your question.
These sections describe how you can help keep your article from being
one of the "skipped" ones.
Is there a better place to ask your question?
Question should be about Perl, not about the application area
It can be difficult to separate out where your problem really is,
but you should make a conscious effort to post to the most
applicable newsgroup. That is, after all, where you are the most
likely to find the people who know how to answer your question.
Being able to "partition" a problem is an essential skill for
effectively troubleshooting programming problems. If you don't get
that right, you end up looking for answers in the wrong places.
It should be understood that you may not know that the root of your
problem is not Perl-related (the two most frequent ones are CGI and
Operating System related), so off-topic postings will happen from
time to time. Be gracious when someone helps you find a better place
to ask your question by pointing you to a more applicable newsgroup.
How to participate (post) in the clpmisc community
Carefully choose the contents of your Subject header
You have 40 precious characters of Subject to win out and be one of
the posts that gets read. Don't waste them. Take care while
composing them, they are the key that opens the door to getting an
answer.
Spend them indicating what aspect of Perl others will find if they
should decide to read your article.
Do not spend them indicating "experience level" (guru, newbie...).
Do not spend them pleading (please read, urgent, help!...).
Do not spend them on non-Subjects (Perl question, one-word
Subject...)
For more information on choosing a Subject see "Choosing Good
Subject Lines":
http://www.cpan.org/authors/id/D/DM/DMR/subjects.post
Part of the beauty of newsgroup dynamics, is that you can contribute
to the community with your very first post! If your choice of
Subject leads a fellow Perler to find the thread you are starting,
then even asking a question helps us all.
Use an effective followup style
When composing a followup, quote only enough text to establish the
context for the comments that you will add. Always indicate who
wrote the quoted material. Never quote an entire article. Never
quote a .signature (unless that is what you are commenting on).
Intersperse your comments *following* each section of quoted text to
which they relate. Unappreciated followup styles are referred to as
"top-posting", "Jeopardy" (because the answer comes before the
question), or "TOFU" (Text Over, Fullquote Under).
Reversing the chronology of the dialog makes it much harder to
understand (some folks won't even read it if written in that style).
For more information on quoting style, see:
http://web.presby.edu/~nnqadmin/nnq/nquote.html
Speak Perl rather than English, when possible
Perl is much more precise than natural language. Saying it in Perl
instead will avoid misunderstanding your question or problem.
Do not say: I have variable with "foo\tbar" in it.
Instead say: I have $var = "foo\tbar", or I have $var = 'foo\tbar',
or I have $var = <DATA> (and show the data line).
Ask perl to help you
You can ask perl itself to help you find common programming mistakes
by doing two things: enable warnings (perldoc warnings) and enable
"strict"ures (perldoc strict).
You should not bother the hundreds/thousands of readers of the
newsgroup without first seeing if a machine can help you find your
problem. It is demeaning to be asked to do the work of a machine. It
will annoy the readers of your article.
You can look up any of the messages that perl might issue to find
out what the message means and how to resolve the potential mistake
(perldoc perldiag). If you would like perl to look them up for you,
you can put "use diagnostics;" near the top of your program.
Do not re-type Perl code
Use copy/paste or your editor's "import" function rather than
attempting to type in your code. If you make a typo you will get
followups about your typos instead of about the question you are
trying to get answered.
Provide enough information
If you do the things in this item, you will have an Extremely Good
chance of getting people to try and help you with your problem!
These features are a really big bonus toward your question winning
out over all of the other posts that you are competing with.
First make a short (less than 20-30 lines) and *complete* program
that illustrates the problem you are having. People should be able
to run your program by copy/pasting the code from your article. (You
will find that doing this step very often reveals your problem
directly. Leading to an answer much more quickly and reliably than
posting to Usenet.)
Describe *precisely* the input to your program. Also provide example
input data for your program. If you need to show file input, use the
__DATA__ token (perldata.pod) to provide the file contents inside of
your Perl program.
Show the output (including the verbatim text of any messages) of
your program.
Describe how you want the output to be different from what you are
getting.
If you have no idea at all of how to code up your situation, be sure
to at least describe the 2 things that you *do* know: input and
desired output.
Do not provide too much information
Do not just post your entire program for debugging. Most especially
do not post someone *else's* entire program.
Do not post binaries, HTML, or MIME
clpmisc is a text only newsgroup. If you have images or binaries
that explain your question, put them in a publically accessible
place (like a Web server) and provide a pointer to that location. If
you include code, cut and paste it directly in the message body.
Don't attach anything to the message. Don't post vcards or HTML.
Many people (and even some Usenet servers) will automatically filter
out such messages. Many people will not be able to easily read your
post. Plain text is something everyone can read.
Social faux pas to avoid
The first two below are symptoms of lots of FAQ asking here in clpmisc.
It happens so often that folks will assume that it is happening yet
again. If you have looked but not found, or found but didn't understand
the docs, say so in your article.
Asking a Frequently Asked Question
It should be understood that you may have missed the applicable FAQ
when you checked, which is not a big deal. But if the Frequently
Asked Question is worded similar to your question, folks will assume
that you did not look at all. Don't become indignant at pointers to
the FAQ, particularly if it solves your problem.
Asking a question easily answered by a cursory doc search
If folks think you have not even tried the obvious step of reading
the docs applicable to your problem, they are likely to become
annoyed.
If you are flamed for not checking when you *did* check, then just
shrug it off (and take the answer that you got).
Asking for emailed answers
Emailed answers benefit one person. Posted answers benefit the
entire community. If folks can take the time to answer your
question, then you can take the time to go get the answer in the
same place where you asked the question.
It is OK to ask for a *copy* of the answer to be emailed, but many
will ignore such requests anyway. If you munge your address, you
should never expect (or ask) to get email in response to a Usenet
post.
Ask the question here, get the answer here (maybe).
Beware of saying "doesn't work"
This is a "red flag" phrase. If you find yourself writing that,
pause and see if you can't describe what is not working without
saying "doesn't work". That is, describe how it is not what you
want.
Sending a "stealth" Cc copy
A "stealth Cc" is when you both email and post a reply without
indicating *in the body* that you are doing so.
Be extra cautious when you get upset
Count to ten before composing a followup when you are upset
This is recommended in all Usenet newsgroups. Here in clpmisc, most
flaming sub-threads are not about any feature of Perl at all! They
are most often for what was seen as a breach of netiquette. If you
have lurked for a bit, then you will know what is expected and won't
make such posts in the first place.
But if you get upset, wait a while before writing your followup. I
recommend waiting at least 30 minutes.
Count to ten after composing and before posting when you are upset
After you have written your followup, wait *another* 30 minutes
before committing yourself by posting it. You cannot take it back
once it has been said.
AUTHOR
Tad McClellan and many others on the comp.lang.perl.misc newsgroup.
--
Tad McClellan
email: perl -le "print scalar reverse qq/moc.noitatibaher\100cmdat/"
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
Administrivia:
To submit articles to comp.lang.perl.announce, send your article to
clpa@perl.com.
Back issues are available via anonymous ftp from
ftp://cil-www.oce.orst.edu/pub/perl/old-digests.
#For other requests pertaining to the digest, send mail to
#perl-users-request@ruby.oce.orst.edu. Do not waste your time or mine
#sending perl questions to the -request address, I don't have time to
#answer them even if I did know the answer.
------------------------------
End of Perl-Users Digest V11 Issue 2690
***************************************
