The :sealed attribute is a statement about a class's @ISA: you are saying you are using its compile-time setting. And because we invoke $class->can to do the lookup, module authors who override UNIVERSAL::can() with a customized one can support AUTOLOADed methods themselves.
Under :sealed, you control which lexical object references you want to use compile-time method lookups (via can()), by declaring them with a class (type), or avoiding doing that in the lexical's declaration. It only impacts your subroutine definitions that declare :sealed and a typed lexicals, not any other module's code elsewhere. You absolutely *can* use sealed.pm outside mod_perl, but you need to be wary about using typed lexicals on your method argument stack, because end-users may pass properly derived objects to your method, and will expect your module to use the derived-class's overrides of any method calls in your codebase. Basically the law of the land is that consumers of an API expect all method calls to operate the way *virtual* method calls work in Java/C++. However, what you do internally with API's outside of your published API's argument stack is fair game for :sealed. My advice that it's only practical to seal XS method calls remains. On Wed, Aug 31, 2022 at 9:52 AM Joe Schaefer <j...@sunstarsys.com> wrote: > Submitted a Pull Request for the Generate.xs patch: > https://github.com/rurban/b-generate/pull/2 > Added more comments to sealed.pm to explain the rationale behind the # > replace $methop logic, > since it differs from what Doug did back in 2000. > > On Tue, Aug 30, 2022 at 2:52 PM Joe Schaefer <j...@sunstarsys.com> wrote: > >> Take a walk down history lane with me here: >> https://www.perl.com/pub/2000/06/dougpatch.html/ >> >> Like ithreads, the idea was sparked from Gurusamy's genius, coded up by >> Doug, and largely forgotten by p5p politics. >> It's not that it couldn't be done, they arrived at the place where it >> *shouldn't* be done, which was deflating for mod_perl fans. >> Simon Couzens made a lot of inroads since, with modularized Perl >> compilers and B::Generate, but it wasn't until >> Perl7 that I was motivated to try any way forward, on a more limited, >> controllable scale. >> >> What do you think? How should this piece of the mod_perl puzzle fit in >> to the CPAN universe? >> >> On Tue, Aug 30, 2022 at 2:12 PM Joe Schaefer <j...@sunstarsys.com> wrote: >> >>> Every method call that's implemented in XS is looked-up at compile-time >>> in that script, even for class methods. >>> That's the sweet spot for :sealed. The only other things I do with it >>> are a few hot methods in Dotiac::DTL::Core, but that's probably not worth >>> the bother. >>> >>> On Tue, Aug 30, 2022 at 1:14 PM Joe Schaefer <j...@sunstarsys.com> wrote: >>> >>>> Just look through my commit history on this sample Registry script to >>>> see what's involved in getting sealed activated on your scripts. >>>> >>>> https://github.com/SunStarSys/cms/blob/master/enquiry.pl >>>> >>>> On Tue, Aug 30, 2022 at 1:12 PM Joe Schaefer <j...@sunstarsys.com> >>>> wrote: >>>> >>>>> It'd be pretty harmless to apply the RegistryCooker.pm patch once we >>>>> find a home for sealed.pm (either in this project or as a stand-alone >>>>> pragma on CPAN). >>>>> Nothing will segfault without consciously using types on your lexical >>>>> object reference declarations; otherwise it's a giant noop. >>>>> >>>>> On Tue, Aug 30, 2022 at 12:53 PM Joe Schaefer <j...@sunstarsys.com> >>>>> wrote: >>>>> >>>>>> If you really beat the hell out of it thread-wise, sealed.pm v4.0.0 >>>>>> will still segfault, but there's not much more I can do with the code at >>>>>> this point to prevent that. >>>>>> B::Generate doesn't really support what I'm doing here, which is to >>>>>> do surgery on an existing op-tree, instead of just playing around with a >>>>>> user-generated one. >>>>>> There's no good way to remove the target "method_named" op that we're >>>>>> replacing with a gv_op. If that can't be supported using B::OP APIs, >>>>>> then >>>>>> it should >>>>>> be handled from perl itself. The problem is that the politics around >>>>>> the feature were never resolved, because nobody wants to change the >>>>>> default >>>>>> "virtual method" >>>>>> behavior of Perl's OO-runtime-lookups. Now with the new :sealed >>>>>> SUBROUTINE ATTRIBUTE, it's only enabled for people (like us) who want it >>>>>> conditionally applied, >>>>>> just like we do for the :method attribute. >>>>>> >>>>>> On Tue, Aug 30, 2022 at 11:26 AM Joe Schaefer <j...@sunstarsys.com> >>>>>> wrote: >>>>>> >>>>>>> Someday this patch might be interesting: >>>>>>> >>>>>>> diff -u RegistryCooker.pm~ RegistryCooker.pm >>>>>>> --- RegistryCooker.pm~ 2022-08-30 11:10:19.790171019 -0400 >>>>>>> +++ RegistryCooker.pm 2022-08-30 11:12:34.319572045 -0400 >>>>>>> @@ -399,7 +399,8 @@ >>>>>>> my $eval = join '', >>>>>>> 'package ', >>>>>>> $self->{PACKAGE}, ";", >>>>>>> - "sub handler {", >>>>>>> + "use base 'sealed';", >>>>>>> + "sub handler :Sealed {", >>>>>>> "local \$0 = '$script_name';", >>>>>>> $nph, >>>>>>> $shebang, >>>>>>> >>>>>>> On Mon, Aug 29, 2022 at 2:21 PM Joe Schaefer <j...@sunstarsys.com> >>>>>>> wrote: >>>>>>> >>>>>>>> Forgive me for the pent up frustration of having our wonderful >>>>>>>> mod_perl project being completely ignored and abandoned by the Perl >>>>>>>> Steering Committee's frivolous lingustic interests over the years >>>>>>>> since the >>>>>>>> Parrot announcement. >>>>>>>> SaywerX gave us a reason to be hopeful again. Let's see what they >>>>>>>> do with it. >>>>>>>> >>>>>>>> On Mon, Aug 29, 2022 at 1:34 PM Joe Schaefer <j...@sunstarsys.com> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> If the Perl steering committee had any brains left it would have >>>>>>>>> capitalized on the perl 5.34 release and Co announced modperl2 ithread >>>>>>>>> compatibility now available with Perl7’s new release. >>>>>>>>> >>>>>>>>> Instead they are going to kick the tires on the defaults for >>>>>>>>> strictures and warnings until nobody cares any more. >>>>>>>>> >>>>>>>>> Get Outlook for iOS <https://aka.ms/o0ukef> >>>>>>>>> ------------------------------ >>>>>>>>> *From:* Joe Schaefer <j...@sunstarsys.com> >>>>>>>>> *Sent:* Monday, August 29, 2022 1:17:17 PM >>>>>>>>> *To:* mod_perl list <modperl@perl.apache.org> >>>>>>>>> *Subject:* Re: sealed.pm v4.0.0 is out >>>>>>>>> >>>>>>>>> The only reason I’ve been vacillating about glibc/malloc thread >>>>>>>>> safety is because I couldn’t fathom the fact that people still >>>>>>>>> believed >>>>>>>>> modperl isn’t compatible with mpm_event at this point in the Perl7 >>>>>>>>> storyline. The old segfaults of the past that happened in glibc >>>>>>>>> malloc >>>>>>>>> were because Perl was corrupting the heap in some other part of the >>>>>>>>> codebase, and there’s no simple way to track it down without a tool >>>>>>>>> like >>>>>>>>> Valgrind, but we weren’t successful with that effort either. >>>>>>>>> >>>>>>>>> Get Outlook for iOS <https://aka.ms/o0ukef> >>>>>>>>> ------------------------------ >>>>>>>>> *From:* Joe Schaefer <j...@sunstarsys.com> >>>>>>>>> *Sent:* Monday, August 29, 2022 1:08:00 PM >>>>>>>>> *To:* mod_perl list <modperl@perl.apache.org> >>>>>>>>> *Subject:* Re: sealed.pm v4.0.0 is out >>>>>>>>> >>>>>>>>> Religiously avoid setting up per request ithread environment >>>>>>>>> variables. Just use PerlSetEnv in your Webserver config. Everything >>>>>>>>> we did >>>>>>>>> in modperl to support CGI scripts is a train wreck. >>>>>>>>> >>>>>>>>> Get Outlook for iOS <https://aka.ms/o0ukef> >>>>>>>>> ------------------------------ >>>>>>>>> *From:* Joe Schaefer <j...@sunstarsys.com> >>>>>>>>> *Sent:* Monday, August 29, 2022 1:04:03 PM >>>>>>>>> *To:* mod_perl list <modperl@perl.apache.org> >>>>>>>>> *Subject:* Re: sealed.pm v4.0.0 is out >>>>>>>>> >>>>>>>>> Look into reducing the scope of your interpreters down from the >>>>>>>>> request level to the handler level. If all you are doing is running >>>>>>>>> registry scripts, you will get even better scaling out of just a few >>>>>>>>> ithreads per worker process. >>>>>>>>> >>>>>>>>> Get Outlook for iOS <https://aka.ms/o0ukef> >>>>>>>>> ------------------------------ >>>>>>>>> *From:* Joe Schaefer <j...@sunstarsys.com> >>>>>>>>> *Sent:* Monday, August 29, 2022 12:57:14 PM >>>>>>>>> *To:* mod_perl list <modperl@perl.apache.org> >>>>>>>>> *Subject:* Re: sealed.pm v4.0.0 is out >>>>>>>>> >>>>>>>>> The only impact to your work with modperl is that you will need to >>>>>>>>> assess the ithread-safety of your dependent XS-based modules. For >>>>>>>>> example, >>>>>>>>> use a JSON::XS thread safe alternative- there are several. >>>>>>>>> >>>>>>>>> Get Outlook for iOS <https://aka.ms/o0ukef> >>>>>>>>> ------------------------------ >>>>>>>>> *From:* Joe Schaefer <j...@sunstarsys.com> >>>>>>>>> *Sent:* Monday, August 29, 2022 12:49:22 PM >>>>>>>>> *To:* mod_perl list <modperl@perl.apache.org> >>>>>>>>> *Subject:* Re: sealed.pm v4.0.0 is out >>>>>>>>> >>>>>>>>> There is a mountain of awful advice floating around about >>>>>>>>> ithreads, including pretty much everything going on in Raku around >>>>>>>>> adopting >>>>>>>>> the node.js model instead. It is safe to ignore all that now that >>>>>>>>> SawyerX >>>>>>>>> spit polished all of the perl5 internals. >>>>>>>>> >>>>>>>>> Get Outlook for iOS <https://aka.ms/o0ukef> >>>>>>>>> ------------------------------ >>>>>>>>> *From:* Joe Schaefer <j...@sunstarsys.com> >>>>>>>>> *Sent:* Monday, August 29, 2022 12:40:43 PM >>>>>>>>> *To:* mod_perl list <modperl@perl.apache.org> >>>>>>>>> *Subject:* Re: sealed.pm v4.0.0 is out >>>>>>>>> >>>>>>>>> Many of the performance hacks we’ve encouraged over the years, eg >>>>>>>>> around HTTPD’s lingering close effect, are obsoleted with ithreads. >>>>>>>>> Unless >>>>>>>>> you send flush buckets down the output filter stack yourself, the >>>>>>>>> “response >>>>>>>>> handler” phase exits long before the “connection handler” starts >>>>>>>>> making non >>>>>>>>> blocking socket system calls. So you need an order of magnitude fewer >>>>>>>>> ithreads than you do prefork children in a multitier arch. >>>>>>>>> >>>>>>>>> Get Outlook for iOS <https://aka.ms/o0ukef> >>>>>>>>> ------------------------------ >>>>>>>>> *From:* Joe Schaefer <j...@sunstarsys.com> >>>>>>>>> *Sent:* Sunday, August 28, 2022 11:09:14 AM >>>>>>>>> *To:* mod_perl list <modperl@perl.apache.org> >>>>>>>>> *Subject:* Re: sealed.pm v4.0.0 is out >>>>>>>>> >>>>>>>>> Benchmark ran on my 2021 Dell Precision Laptop w/ 8 cores + HT >>>>>>>>> (so 16vCPU) and Ubuntu 22.04 inside WSL2. Never topped 50% avg CPU, >>>>>>>>> and >>>>>>>>> almost all of the CPU was in userland (not system calls). >>>>>>>>> >>>>>>>>> On Sat, Aug 27, 2022 at 11:42 AM <j...@sunstarsys.com> wrote: >>>>>>>>> >>>>>>>>> See https://sunstarsys.com/essays/perl7-sealed-lexicals. For the >>>>>>>>> full effect, you will need to build B::Generate with this patched >>>>>>>>> version >>>>>>>>> instead: https://github.com/SunStarSys/cms/blob/master/Generate.xs >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Sample mod_perl config + benchmarks: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> <IfModule mpm_event_module> >>>>>>>>> >>>>>>>>> StartServers 2 >>>>>>>>> >>>>>>>>> MinSpareThreads 100 >>>>>>>>> >>>>>>>>> MaxSpareThreads 500 >>>>>>>>> >>>>>>>>> ThreadLimit 1000 >>>>>>>>> >>>>>>>>> ThreadsPerChild 100 >>>>>>>>> >>>>>>>>> MaxRequestWorkers 1000000 >>>>>>>>> >>>>>>>>> MaxConnectionsPerChild 0 >>>>>>>>> >>>>>>>>> </IfModule> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> <IfModule mod_perl.c> >>>>>>>>> >>>>>>>>> PerlSwitches -T -I/home/joesuf4/src/cms/lib >>>>>>>>> >>>>>>>>> PerlInterpStart 2 >>>>>>>>> >>>>>>>>> PerlInterpMax 4 >>>>>>>>> >>>>>>>>> PerlInterpMinSpare 1 >>>>>>>>> >>>>>>>>> PerlInterpMaxSpare 4 >>>>>>>>> >>>>>>>>> PerlInterpMaxRequests 1000000 >>>>>>>>> >>>>>>>>> PerlOptions +GlobalRequest >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> <Directory /home/joesuf4/src/cms> >>>>>>>>> >>>>>>>>> Require all granted >>>>>>>>> >>>>>>>>> AddHandler perl-script .pl >>>>>>>>> >>>>>>>>> PerlResponseHandler ModPerl::Registry >>>>>>>>> >>>>>>>>> Options +ExecCGI >>>>>>>>> >>>>>>>>> </Directory> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> <Directory /home/joesuf4/src/trunk/content> >>>>>>>>> >>>>>>>>> Require all granted >>>>>>>>> >>>>>>>>> </Directory> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> <VirtualHost *:80> >>>>>>>>> >>>>>>>>> ServerName localhost >>>>>>>>> >>>>>>>>> DocumentRoot /home/joesuf4/src/trunk/content >>>>>>>>> >>>>>>>>> Alias /perl-script /home/joesuf4/src/cms >>>>>>>>> >>>>>>>>> </VirtualHost> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> </IfModule> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> ab -n 10000 -c 1000 http://localhost/perl-script/enquiry.pl >>>>>>>>> >>>>>>>>> This is ApacheBench, Version 2.3 <$Revision: 1879490 $> >>>>>>>>> >>>>>>>>> Copyright 1996 Adam Twiss, Zeus Technology Ltd, >>>>>>>>> http://www.zeustech.net/ >>>>>>>>> >>>>>>>>> Licensed to The Apache Software Foundation, http://www.apache.org/ >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Benchmarking localhost (be patient) >>>>>>>>> >>>>>>>>> Completed 1000 requests >>>>>>>>> >>>>>>>>> Completed 2000 requests >>>>>>>>> >>>>>>>>> Completed 3000 requests >>>>>>>>> >>>>>>>>> Completed 4000 requests >>>>>>>>> >>>>>>>>> Completed 5000 requests >>>>>>>>> >>>>>>>>> Completed 6000 requests >>>>>>>>> >>>>>>>>> Completed 7000 requests >>>>>>>>> >>>>>>>>> Completed 8000 requests >>>>>>>>> >>>>>>>>> Completed 9000 requests >>>>>>>>> >>>>>>>>> Completed 10000 requests >>>>>>>>> >>>>>>>>> Finished 10000 requests >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Server Software: Apache/2.4.52 >>>>>>>>> >>>>>>>>> Server Hostname: localhost >>>>>>>>> >>>>>>>>> Server Port: 80 >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Document Path: /perl-script/enquiry.pl >>>>>>>>> >>>>>>>>> Document Length: 1329 bytes >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Concurrency Level: 1000 >>>>>>>>> >>>>>>>>> Time taken for tests: 1.218 seconds >>>>>>>>> >>>>>>>>> Complete requests: 10000 >>>>>>>>> >>>>>>>>> Failed requests: 0 >>>>>>>>> >>>>>>>>> Total transferred: 15010000 bytes >>>>>>>>> >>>>>>>>> HTML transferred: 13290000 bytes >>>>>>>>> >>>>>>>>> Requests per second: 8207.94 [#/sec] (mean) >>>>>>>>> >>>>>>>>> Time per request: 121.833 [ms] (mean) >>>>>>>>> >>>>>>>>> Time per request: 0.122 [ms] (mean, across all concurrent >>>>>>>>> requests) >>>>>>>>> >>>>>>>>> Transfer rate: 12031.37 [Kbytes/sec] received >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Connection Times (ms) >>>>>>>>> >>>>>>>>> min mean[+/-sd] median max >>>>>>>>> >>>>>>>>> Connect: 0 2 6.2 0 24 >>>>>>>>> >>>>>>>>> Processing: 4 93 49.6 82 458 >>>>>>>>> >>>>>>>>> Waiting: 1 80 44.5 71 455 >>>>>>>>> >>>>>>>>> Total: 17 95 49.5 84 458 >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Percentage of the requests served within a certain time (ms) >>>>>>>>> >>>>>>>>> 50% 84 >>>>>>>>> >>>>>>>>> 66% 100 >>>>>>>>> >>>>>>>>> 75% 112 >>>>>>>>> >>>>>>>>> 80% 120 >>>>>>>>> >>>>>>>>> 90% 147 >>>>>>>>> >>>>>>>>> 95% 173 >>>>>>>>> >>>>>>>>> 98% 233 >>>>>>>>> >>>>>>>>> 99% 318 >>>>>>>>> >>>>>>>>> 100% 458 (longest request) >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> % pgrep -f apache2 | xargs -n1 ps -uwww >>>>>>>>> >>>>>>>>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME >>>>>>>>> COMMAND >>>>>>>>> >>>>>>>>> root 442827 0.0 0.1 18180 14244 ? Ss 11:27 0:00 >>>>>>>>> /usr/sbin/apache2 -k start >>>>>>>>> >>>>>>>>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME >>>>>>>>> COMMAND >>>>>>>>> >>>>>>>>> www-data 446387 1.7 1.5 7549352 129692 ? Sl 11:28 0:12 >>>>>>>>> /usr/sbin/apache2 -k start >>>>>>>>> >>>>>>>>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME >>>>>>>>> COMMAND >>>>>>>>> >>>>>>>>> www-data 451006 15.2 1.5 7483708 128468 ? Sl 11:39 0:10 >>>>>>>>> /usr/sbin/apache2 -k start >>>>>>>>> >>>>>>>>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME >>>>>>>>> COMMAND >>>>>>>>> >>>>>>>>> www-data 451317 11.7 1.4 7483772 119836 ? Sl 11:39 0:07 >>>>>>>>> /usr/sbin/apache2 -k start >>>>>>>>> >>>>>>>>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME >>>>>>>>> COMMAND >>>>>>>>> >>>>>>>>> www-data 451629 6.4 1.3 7483804 113012 ? Sl 11:39 0:03 >>>>>>>>> /usr/sbin/apache2 -k start >>>>>>>>> >>>>>>>>> USER PID %CPU %MEM VSZ RSS TTY STAT START TIME >>>>>>>>> COMMAND >>>>>>>>> >>>>>>>>> www-data 451929 1.1 1.4 7483816 116668 ? Sl 11:39 0:00 >>>>>>>>> /usr/sbin/apache2 -k start >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> -- >>>>>>>>> Joe Schaefer, Ph.D. >>>>>>>>> We only build what you need built. >>>>>>>>> <j...@sunstarsys.com> >>>>>>>>> 954.253.3732 <//954.253.3732> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Joe Schaefer, Ph.D. >>>>>>>> We only build what you need built. >>>>>>>> <j...@sunstarsys.com> >>>>>>>> 954.253.3732 <//954.253.3732> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Joe Schaefer, Ph.D. >>>>>>> We only build what you need built. >>>>>>> <j...@sunstarsys.com> >>>>>>> 954.253.3732 <//954.253.3732> >>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> -- >>>>>> Joe Schaefer, Ph.D. >>>>>> We only build what you need built. >>>>>> <j...@sunstarsys.com> >>>>>> 954.253.3732 <//954.253.3732> >>>>>> >>>>>> >>>>>> >>>>> >>>>> -- >>>>> Joe Schaefer, Ph.D. >>>>> We only build what you need built. >>>>> <j...@sunstarsys.com> >>>>> 954.253.3732 <//954.253.3732> >>>>> >>>>> >>>>> >>>> >>>> -- >>>> Joe Schaefer, Ph.D. >>>> We only build what you need built. >>>> <j...@sunstarsys.com> >>>> 954.253.3732 <//954.253.3732> >>>> >>>> >>>> >>> >>> -- >>> Joe Schaefer, Ph.D. >>> We only build what you need built. >>> <j...@sunstarsys.com> >>> 954.253.3732 <//954.253.3732> >>> >>> >>> >> >> -- >> Joe Schaefer, Ph.D. >> We only build what you need built. >> <j...@sunstarsys.com> >> 954.253.3732 <//954.253.3732> >> >> >> > > -- > Joe Schaefer, Ph.D. > We only build what you need built. > <j...@sunstarsys.com> > 954.253.3732 <//954.253.3732> > > > -- Joe Schaefer, Ph.D. We only build what you need built. <j...@sunstarsys.com> 954.253.3732 <//954.253.3732>
