This Week on perl5-porters - 26 June-2 July 2006
"But having it match what perl6 will do is even more important than
having it make perfect sense, IMO.", Yitzchak Scott-Thoennes,
thinking about forwards compatibility.
Topics of Interest
"exit" and "die" in threads
Following on from the threads 1.33 conversation last week that was
given short shrift in last week's summary (sorry Jerry), Jerry D.
Hedden put forward a proposal to nail down the semantics of what
happens when a thread calls "exit" (and more to the point, what to do
about everything that might want to clean up after itself). Throw in a
"__WARN__" and/or "__DIE__" handler or two, and you're starting to
talk about some serious fun.
Jan Dubois and Rafael Garcia-Suarez commented on a number of points
that Jerry raised, and while Rafael didn't agree with a few things, he
was quick to point out that he didn't have any definite opinions one
way or another, only that he wanted the best possible solution to come
out the discussion.
Dave Mitchell wondered whether it wouldn't be possible to add an
"exit" method to the threads class, which would apply only to the
thread, leaving the core "exit" to behave as usual.
In through the out door
http://xrl.us/ot6z
Jerry the checked with the porters to see whether everyone agreed to
what he thought threads should do. Jan and Liz Mattijsen gave their
assent.
http://xrl.us/ot63
Just to be really certain, Jerry then posted a consensuality matrix,
to get people who had made suggestions to sign off, or explain what
they disagreed about. The moral of the story is that calling "exit()"
as a thread method ends the thread, but calling "exit()" ends
everything, modulo some differences in opinion over how much to warn
about and when.
fluid neon origami trick
http://xrl.us/ot65
Jerry went about modifying the threads module to do all this and ran
into problems with too many "ENTER"s and not enough "LEAVE"s and the
like. Jan said that he had no time to look closely, but eyeballed
Jerry's code, sketched out a brief idea of what needed to be done.
Jerry picked it up and ran with it, and straightened out all the
problems.
Balancing act
http://xrl.us/ot68
By the end of the week, Jerry had the new implementation up and
running to his satisfaction, except for a nagging problem of "die"
messages not being captured by the test harness, thus polluting the
output.
Weaving in and out
http://xrl.us/ot7b
Dave Mitchell listed the available possibilities:
New month, new thread
http://xrl.us/ot7e
The last remaining eval leaks
After having looked over the stellar achievements of Dave Mitchell in
removing "eval" leaks (caused when the "eval"'ed code fails), Nicholas
Clark listed the remaining known leaks and asked for help in trying to
identify the code paths taken (which would help in figuring out how to
plug them).
Dr. Ruud suggested taking a look at a tool called "MemProf". Dominic
Dunlop answered the question with a question, and offered another leak
to add to the list.
Lost property
http://xrl.us/ot7g
Did You Know This Worked?
chromatic posted a short, sharp snippet of C, showing how easy it is
to insert your own XS code into an existing op code, which opens up
all sorts of interesting possibilities.
http://xrl.us/ot7j
Is $A::::B::C a bug or feature?
Continuing in the I-didn't-know-Perl-could-do-that vein, Chip
Salzenberg discovered that this meant that "C" is inside package
"::B::" which in turn is inside "A", and thought it was all rather
evil.
Sadahiro Tomoyuki traced the change down to somewhere between 5.004_04
and 5.004_05, when "scan_words" in toke.c was modified to permit this,
some time back in 2003. No-one appeared to remember the reason.
http://xrl.us/ot7m
Questions regarding smart match and scalar upgrades in Perl 5
Steve Peters was going over the new smart match ("~~") operator from
Perl 6, that Robin Houston added to "blead" last year, and making sure
it was well tested. He wrote a couple of tests, was puzzled by the
results, and wondered whether the problem lay with the implementation,
or with the documentation.
Yitzchak Scott-Thoennes analysed Steve's reasoning, but no firm
conclusions were made.
http://xrl.us/ot7o
"Win32API::File" now in core
Steve Hay announced that he had set things up to make "Win32API::File"
a first-class dual-lifed module, in "blead" and on CPAN. He called on
Jan Dubois to see whether Jan needed or wanted to do anything about
"libwin32". There was discussion of moving files from
"win32/ext/Win32" to "ext/Win32", which would ease the building of
perl on Cygwin.
It just got bigger
http://xrl.us/ot7q
Some discussion followed as to whether or not it would make it in time
for 5.8.9.
http://xrl.us/ot7r
Patches of Interest
vms.c - null termination of string missing.
John E. Malmberg offered a short patch to correct a function that
failed to append a null character to strings, which gave the
underlying C library indigestion since it was expecting one. Rafael
applied.
Overshooting yourself in the foot
http://xrl.us/ot7s
Similarly, Jarkko Hietaniemi taught "cflags.SH" to scan the gcc
warning flags only once:
http://xrl.us/ot7t
Adding "splint" support
Andy Lester set about adding "splint" (a "lint"-like tool) support for
the porters. First off he created some embed.pl enhancements:
http://xrl.us/ot7u
And then followed with some Makefile "splint" support. It doesn't
quite do everything that it should, and Andy called upon other people
(hi Jarkko!) for help.
http://xrl.us/ot7w
Dispatches from the "const"ing front
Elsewhere in the code base, Andy tweaked DProf.xs to only compile a
small static function if in fact it was actually required in the
current configuration.
http://xrl.us/ot7z
He then turned his attention to ye cruftey olde mathoms.c. Just
because they're obsolete doesn't mean they can't be squeaky clean.
http://xrl.us/ot73
And for dessert, Andy tidied up mg.c, by localising a variable here
and there, and encapsulating "Perl_*" calls in macros.
http://xrl.us/ot76
Removing an inconsistent close $fh
Vadim Konovalov wanted to clean up win32/buildext.pl by removing an
explicit "close", since just nearby is a similar "open" that also
omits the "close".
Yves Orton that a better idea was to rewrite the code, because it's a
complete mess. (Amd it isn't particularly big, either).
Innovations in brace placement
http://xrl.us/ot78
Watching the smoke signals
Smoke [5.9.4] 28420 FAIL(FMm) OSF1 V5.1 (EV6/4 cpu)]
Jarkko noted some failures had been cropping up in recent smokes, but
didn't feel they were specific to the platform (Tru64) he was running.
Nicholas Clark explained what the issues were. One was a simple test
design issue that anybody with a reasonable grasp of designing tests
should be able to figure out. Alas, no-one had volunteered to have a
look. Jarkko asked for more background.
Background check
http://xrl.us/nf28
The other issue was one of "eval" leaks, and Jarkko courageously
deferred to Dave Mitchell as the likely fixer of that.
Snot funny
http://xrl.us/ot8b
Smoke [5.9.4] 28452 FAIL(F) MSWin32 WinXP/.Net SP2 (x86/2 cpu)
Anno Siegel looked at one of Steve Hay's smokes, and wondered how one
was supposed to interpret the results. H. Merijn Brand explained the
general case, and Steve explained what was going wrong in this
particular case.
Inconsistent test results (between TEST and harness)
http://xrl.us/ot8d
Smoke [5.9.4] 28456 FAIL(c) Solaris 2.10 (i386/1 cpu)
H.Merijn looked at one of Abe Timmerman's failing Solaris smokes and
traced it down to a change he'd made to "Configure" following on from
a suggestion from Andy Dougherty. Andy thanked H.Merijn for the catch
and noted that the entire hack was no longer needed anyway, since the
original problem (one of 64-bit tests) has since been fixed.
http://xrl.us/ot8g
New and old bugs from RT
problem on installing DBI module (#39527)
Jan Dubois wrote to say that it is possible to install "DBD::Oracle"
for ActiveState, at the price of also downloading many megabytes of
Oracle libraries.
But alas, only for 5.6
http://xrl.us/ot8j
Pattern Match fails for specific length string (#39583)
The code was corrected to handle this problem, and Yves folded the
original bug report into the test suite. Yves then went on to rewrite
the regexp display code, since, up until now, control characters have
always been invisible, which makes it much harder to understand bug
reports when control characters are present.
She's lost control
http://xrl.us/ot8m
nl_langinfo ==> Installation problems (#39625)
Jaymax was having problems upgrading 5.8.2 to 5.8.8. "miniperl" was
dying with a "Undefined symbol "nl_langinfo"" error. No takers as yet.
http://xrl.us/ot8p
Using nonsensical key in %SIG should generate a warning (#39630)
Nik thought that he would have saved a lot of time if perl complained
about trying to use keys in %SIG that don't refer to valid signal
handlers. Rafael thought that the problem might be because that the
code in question was not, in fact, running with warnings enabled.
Ask no questions, tell no lies
http://xrl.us/ot8s
@ISA is not mentioned in "perlvar" (#39633)
Sebastian Schmidt kicked off a long thread about whether or not @ISA
should be referenced in "perlvar" or not. The main dissent was due to
the fact that @ISA isn't particularly special as far as perl is
concerned, it merely has lots of cultural conventions associated with
it.
Nevertheless, it was agreed that "perlvar" should in fact list all
extraordinary variables, with "L<>" references to the appropriate
pages if a better definition already existed elsewhere.
http://xrl.us/ot8u
gcc 3.3 has problems with "__attribute__((unused))" (#39634)
John Gardiner Myers was having some trouble compiling "Encode::Detect"
with the GNU C++ compiler. Andy Dougherty realised that "blead" had
already solved this problem and proposed a couple of patches to get
things going. John, however, had another patch that he thought was
better. After looking at it, Andy did too. He tidied it up slightly,
and suggested that it was fit for inclusion to both "blead" and
"maint".
http://xrl.us/ot8y
Configure (on Solaris 64-bit) fails (#39636)
Marc Esser was having trouble configuring perl on Solaris 10. After a
getting Marc to try a few things, Andy Dougherty believed that he had
isolated the problem in some incorrect hints for Solaris.
http://xrl.us/ot82
filetest problem with "STDIN"/"STDOUT" on Windows (#39637)
Paul Marquess reported that he had had some problems with not being
able to apply "-r" to "\*STDIN" and get a sensible result back on
Windows.
Par for the course
http://xrl.us/ot84
"perldoc -f waitpid" has wrong code example (#39639)
Alexander Gernler mentioned that he thought the snippet explaining
"waitpid" was wrong, and that it should use a "do/while" loop and not
a "do/until" loop. Rafael agreed, and Salvador Fandiño and Dr. Ruud
made a few suggestion about making the snippet truly cross platform
(well, and least Unix and Windows).
Zombie-free zone
http://xrl.us/ot87
XSUB.h in perl v5.8.8 with gcc 3.4.6 (#39644)
Jon V. had a weird compilation error. Rafael suspected that some
errant header was defining a symbol standing in for a function or
something, as a number.
http://xrl.us/ot9a
"DynaLoader" corrupts %ENV (#39647)
Daniel Pfeiffer as having trouble with a Solaris 2.10 box coming to
grief with environment variables eating all available memory. Rafael
had trouble reproducing it. So did Daniel for that matter.
Unfortunately, there's not much to go on.
http://xrl.us/ot9c
"require" and "List::MoreUtils" seg fault (#39650)
Darin McBride had some code worked if "List::MoreUtils" was "use"d,
but dumped core if it was "require"d. Rafael saw that the problem lay
in the module building an iterator as a closure to traverse an array,
but couldn't see off-hand why it should fail.
http://xrl.us/ot9f
perl crashes with simple regex (#39652)
Another back-tracking stack-blowing pattern.
FITNR
http://xrl.us/ot9h
Regex performance with UTF-8 strings (#39654)
Peter J.Holzer discovered that taking a simple byte string and
upgrading it to UTF-8 makes the match go three times slower when the
target remains byte-encoded. Or, to put it another way, if the
polarity of the target and regexp are reversed, performance is awful.
Even Yves admitted to being scared at the amount of effort required to
make the engine do the right thing. It's doable, and he's thought
about it on occasion. Sadahiro Tomoyuki gave Peter a tip that helped
in improve the performance in his particular case.
Fruit at the top of the tree
http://xrl.us/ot9k
Yves went onto to explain far more than you ever wanted to know about
UTF-8, and just how much effort it takes to move to the next character
in a string. Juerd suggested a number of optimisations that, if
implemented, may improve performance. Yves went down the list and
pointed out that nearly all of Juerd's ideas *are* already implemented
in the engine in some way or another.
In other sub-thread, Sadahiro caught a naughty macro that lacked a
parenthesised argument, which Rafael fixed in blead.
It ain't easy
http://xrl.us/ot9n
Perl5 Bug Summary
+ 13 - 7 = 1499
http://xrl.us/ot9q
Ooh, nice RT upgrade
http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
New Core Modules
* ExtUtils::Install version 1.41 released by Yves Orton. No change
in functionality, merely a tweak to the versions to get "blead"
and "CPAN" in sync.
Do the bump
http://xrl.us/ot9r
In Brief
Rafael announced that he was removing references to "5005threads" in
the "perlguts" documentation.
The end of the line
http://xrl.us/ot9t
Steve Hay showed the best settings to get the most out of "malloc" on
the Win32 platform.
http://xrl.us/ot9v
Andy Lester noted that the Coverity defect scan of the codebase had
risen from 35 to 40 in two weeks.
Misfeature creep
http://xrl.us/ot9y
Alan Burlison pointed to Data Race Detection Tool (or DRDT) from Sun,
which is a tool designed to help track down data race issues with
threads.
Might be handy
http://xrl.us/ot93
Sébastien Aperghis-Tramoni posted a small precision about "\Q \E"
inside "m//x", after having spent too much time trying to figure out
why his code wasn't doing what he expected.
DWIM or RTFM
http://xrl.us/ot95
Brendan O'Dea put forward a modest proposal remove "x2p/*", that is,
the awk-to-perl and sed-to-perl scripts, arguing that no-one uses them
anymore. Neither Rafael nor H.Merijn were in favour of such a move.
http://xrl.us/ot98
Craig A. Berry tidied up some POD typos.
http://xrl.us/ouaa
About this summary
This summary was written by David Landgren.
Last week's unfinished opus attracted a comment from Nicholas Clark
asking how other open-source languages deal with the day to day
housekeeping, and he even received an answer!
http://xrl.us/ouad
If you want a bookmarklet approach to viewing bugs and change reports,
there are a couple of bookmarklets that you might find useful on my
page of Perl stuff:
http://www.landgren.net/perl/
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