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Revision 1.59 by root, Thu Apr 24 08:38:13 2008 UTC vs.
Revision 1.65 by root, Fri Apr 25 06:58:12 2008 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt - various supported event loops 5EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6 6
7=head1 SYNOPSIS 7=head1 SYNOPSIS
8 8
9 use AnyEvent; 9 use AnyEvent;
10 10
… …
78 78
79The interface itself is vaguely similar, but not identical to the L<Event> 79The interface itself is vaguely similar, but not identical to the L<Event>
80module. 80module.
81 81
82During the first call of any watcher-creation method, the module tries 82During the first call of any watcher-creation method, the module tries
83to detect the currently loaded event loop by probing whether one of 83to detect the currently loaded event loop by probing whether one of the
84the following modules is already loaded: L<Coro::EV>, L<Coro::Event>, 84following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,
85L<EV>, L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>. The first one 85L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>,
86found is used. If none are found, the module tries to load these modules 86L<POE>. The first one found is used. If none are found, the module tries
87(excluding Event::Lib and Qt) in the order given. The first one that can 87to load these modules (excluding Event::Lib, Qt and POE as the pure perl
88adaptor should always succeed) in the order given. The first one that can
88be successfully loaded will be used. If, after this, still none could be 89be successfully loaded will be used. If, after this, still none could be
89found, AnyEvent will fall back to a pure-perl event loop, which is not 90found, AnyEvent will fall back to a pure-perl event loop, which is not
90very efficient, but should work everywhere. 91very efficient, but should work everywhere.
91 92
92Because AnyEvent first checks for modules that are already loaded, loading 93Because AnyEvent first checks for modules that are already loaded, loading
… …
362 AnyEvent::Impl::Glib based on Glib, third-best choice. 363 AnyEvent::Impl::Glib based on Glib, third-best choice.
363 AnyEvent::Impl::Tk based on Tk, very bad choice. 364 AnyEvent::Impl::Tk based on Tk, very bad choice.
364 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. 365 AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
365 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). 366 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
366 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 367 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
368 AnyEvent::Impl::POE based on POE, not generic enough for full support.
369
370There is no support for WxWidgets, as WxWidgets has no support for
371watching file handles. However, you can use WxWidgets through the
372POE Adaptor, as POE has a Wx backend that simply polls 20 times per
373second, which was considered to be too horrible to even consider for
374AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
375it's adaptor.
376
377AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
378autodetecting them.
367 379
368=item AnyEvent::detect 380=item AnyEvent::detect
369 381
370Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 382Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
371if necessary. You should only call this function right before you would 383if necessary. You should only call this function right before you would
… …
422no warnings; 434no warnings;
423use strict; 435use strict;
424 436
425use Carp; 437use Carp;
426 438
427our $VERSION = '3.2'; 439our $VERSION = '3.3';
428our $MODEL; 440our $MODEL;
429 441
430our $AUTOLOAD; 442our $AUTOLOAD;
431our @ISA; 443our @ISA;
432 444
… …
439 [Coro::Event:: => AnyEvent::Impl::CoroEvent::], 451 [Coro::Event:: => AnyEvent::Impl::CoroEvent::],
440 [EV:: => AnyEvent::Impl::EV::], 452 [EV:: => AnyEvent::Impl::EV::],
441 [Event:: => AnyEvent::Impl::Event::], 453 [Event:: => AnyEvent::Impl::Event::],
442 [Glib:: => AnyEvent::Impl::Glib::], 454 [Glib:: => AnyEvent::Impl::Glib::],
443 [Tk:: => AnyEvent::Impl::Tk::], 455 [Tk:: => AnyEvent::Impl::Tk::],
456 [Wx:: => AnyEvent::Impl::POE::],
457 [Prima:: => AnyEvent::Impl::POE::],
444 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 458 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
445); 459 # everything below here will not be autoprobed as the pureperl backend should work everywhere
446my @models_detect = ( 460 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
447 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 461 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
448 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 462 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
449); 463);
450 464
451our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); 465our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
452 466
453sub detect() { 467sub detect() {
… …
457 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 471 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
458 my $model = "AnyEvent::Impl::$1"; 472 my $model = "AnyEvent::Impl::$1";
459 if (eval "require $model") { 473 if (eval "require $model") {
460 $MODEL = $model; 474 $MODEL = $model;
461 warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1; 475 warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
476 } else {
477 warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;
462 } 478 }
463 } 479 }
464 480
465 # check for already loaded models 481 # check for already loaded models
466 unless ($MODEL) { 482 unless ($MODEL) {
467 for (@REGISTRY, @models, @models_detect) { 483 for (@REGISTRY, @models) {
468 my ($package, $model) = @$_; 484 my ($package, $model) = @$_;
469 if (${"$package\::VERSION"} > 0) { 485 if (${"$package\::VERSION"} > 0) {
470 if (eval "require $model") { 486 if (eval "require $model") {
471 $MODEL = $model; 487 $MODEL = $model;
472 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; 488 warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
… …
659 675
660=over 4 676=over 4
661 677
662=item C<PERL_ANYEVENT_VERBOSE> 678=item C<PERL_ANYEVENT_VERBOSE>
663 679
680By default, AnyEvent will be completely silent except in fatal
681conditions. You can set this environment variable to make AnyEvent more
682talkative.
683
684When set to C<1> or higher, causes AnyEvent to warn about unexpected
685conditions, such as not being able to load the event model specified by
686C<PERL_ANYEVENT_MODEL>.
687
664When set to C<2> or higher, cause AnyEvent to report to STDERR which event 688When set to C<2> or higher, cause AnyEvent to report to STDERR which event
665model it chooses. 689model it chooses.
666 690
667=item C<PERL_ANYEVENT_MODEL> 691=item C<PERL_ANYEVENT_MODEL>
668 692
… …
836 $quit->broadcast; 860 $quit->broadcast;
837 }); 861 });
838 862
839 $quit->wait; 863 $quit->wait;
840 864
865
866=head1 BENCHMARK
867
868To give you an idea of the performance and overheads that AnyEvent adds
869over the backends directly, here is a benchmark of various supported event
870models natively and with anyevent. The benchmark creates a lot of timers
871(with a zero timeout) and io events (watching STDOUT, a pty, to become
872writable), lets them fire exactly once and destroys them again.
873
874Explanation of the fields:
875
876I<watcher> is the number of event watchers created/destroyed. Sicne
877different event models have vastly different performance each backend was
878handed a number of watchers so that overall runtime is acceptable and
879similar to all backends (and keep them from crashing).
880
881I<bytes> is the number of bytes (as measured by resident set size) used by
882each watcher.
883
884I<create> is the time, in microseconds, to create a single watcher.
885
886I<invoke> is the time, in microseconds, used to invoke a simple callback
887that simply counts down.
888
889I<destroy> is the time, in microseconds, to destroy a single watcher.
890
891 name watcher bytes create invoke destroy comment
892 EV/EV 400000 244 0.56 0.46 0.31 EV native interface
893 EV/Any 100000 610 3.52 0.91 0.75
894 CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal
895 Perl/Any 10000 654 4.64 1.22 0.77 pure perl implementation
896 Event/Event 10000 523 28.05 21.38 5.22 Event native interface
897 Event/Any 10000 943 34.43 20.48 1.39
898 Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour
899 Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers
900 POE/Select 2000 6343 94.69 807.65 562.69 POE::Loop::Select
901 POE/Event 2000 6644 108.15 768.19 14.33 POE::Loop::Event
902
903Discussion: The benchmark does I<not> bench scalability of the
904backend. For example a select-based backend (such as the pureperl one) can
905never compete with a backend using epoll. In this benchmark, only a single
906filehandle is used.
907
908EV is the sole leader regarding speed and memory use, which are both
909maximal/minimal. Even when going through AnyEvent, there is only one event
910loop that uses less memory (the Event module natively), and no faster
911event model.
912
913The pure perl implementation is hit in a few sweet spots (both the
914zero timeout and the use of a single fd hit optimisations in the perl
915interpreter and the backend itself), but it shows that it adds very little
916overhead in itself. Like any select-based backend it's performance becomes
917really bad with lots of file descriptors.
918
919The Event module has a relatively high setup and callback invocation cost,
920but overall scores on the third place.
921
922Glib has a little higher memory cost, a bit fster callback invocation and
923has a similar speed as Event.
924
925The Tk backend works relatively well, the fact that it crashes with
926more than 2000 watchers is a big setback, however, as correctness takes
927precedence over speed.
928
929POE, regardless of backend (wether it's pure perl select backend or the
930Event backend) shows abysmal performance and memory usage: Watchers use
931almost 30 times as much memory as EV watchers, and 10 times as much memory
932as both Event or EV via AnyEvent.
933
934Summary: using EV through AnyEvent is faster than any other event
935loop. The overhead AnyEvent adds can be very small, and you should avoid
936POE like the plague if you want performance or reasonable memory usage.
937
938
841=head1 FORK 939=head1 FORK
842 940
843Most event libraries are not fork-safe. The ones who are usually are 941Most event libraries are not fork-safe. The ones who are usually are
844because they are so inefficient. Only L<EV> is fully fork-aware. 942because they are so inefficient. Only L<EV> is fully fork-aware.
845 943
846If you have to fork, you must either do so I<before> creating your first 944If you have to fork, you must either do so I<before> creating your first
847watcher OR you must not use AnyEvent at all in the child. 945watcher OR you must not use AnyEvent at all in the child.
946
848 947
849=head1 SECURITY CONSIDERATIONS 948=head1 SECURITY CONSIDERATIONS
850 949
851AnyEvent can be forced to load any event model via 950AnyEvent can be forced to load any event model via
852$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to 951$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
… …
860 959
861 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } 960 BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
862 961
863 use AnyEvent; 962 use AnyEvent;
864 963
964
865=head1 SEE ALSO 965=head1 SEE ALSO
866 966
867Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, 967Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
868L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, 968L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
869L<Event::Lib>, L<Qt>. 969L<Event::Lib>, L<Qt>, L<POE>.
870 970
871Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, 971Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
872L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, 972L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
873L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, 973L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
874L<AnyEvent::Impl::Qt>. 974L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.
875 975
876Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 976Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
977
877 978
878=head1 AUTHOR 979=head1 AUTHOR
879 980
880 Marc Lehmann <schmorp@schmorp.de> 981 Marc Lehmann <schmorp@schmorp.de>
881 http://home.schmorp.de/ 982 http://home.schmorp.de/

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