1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | AnyEvent - provide framework for multiple event loops |
3 | AnyEvent - provide framework for multiple event loops |
4 | |
4 | |
5 | EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt - various supported event loops |
5 | EV, 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 | |
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78 | |
78 | |
79 | The interface itself is vaguely similar, but not identical to the L<Event> |
79 | The interface itself is vaguely similar, but not identical to the L<Event> |
80 | module. |
80 | module. |
81 | |
81 | |
82 | During the first call of any watcher-creation method, the module tries |
82 | During the first call of any watcher-creation method, the module tries |
83 | to detect the currently loaded event loop by probing whether one of |
83 | to detect the currently loaded event loop by probing whether one of the |
84 | the following modules is already loaded: L<Coro::EV>, L<Coro::Event>, |
84 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
85 | L<EV>, L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>. The first one |
85 | L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>, |
86 | found is used. If none are found, the module tries to load these modules |
86 | L<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 |
87 | to load these modules (excluding Event::Lib, Qt and POE as the pure perl |
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88 | adaptor should always succeed) in the order given. The first one that can |
88 | be successfully loaded will be used. If, after this, still none could be |
89 | be successfully loaded will be used. If, after this, still none could be |
89 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
90 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
90 | very efficient, but should work everywhere. |
91 | very efficient, but should work everywhere. |
91 | |
92 | |
92 | Because AnyEvent first checks for modules that are already loaded, loading |
93 | Because AnyEvent first checks for modules that are already loaded, loading |
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207 | |
208 | |
208 | There are two ways to handle timers: based on real time (relative, "fire |
209 | There are two ways to handle timers: based on real time (relative, "fire |
209 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
210 | in 10 seconds") and based on wallclock time (absolute, "fire at 12 |
210 | o'clock"). |
211 | o'clock"). |
211 | |
212 | |
212 | While most event loops expect timers to specified in a relative way, they use |
213 | While most event loops expect timers to specified in a relative way, they |
213 | absolute time internally. This makes a difference when your clock "jumps", |
214 | use absolute time internally. This makes a difference when your clock |
214 | for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to |
215 | "jumps", for example, when ntp decides to set your clock backwards from |
215 | 2008-01-01, a watcher that you created to fire "after" a second might actually take |
216 | the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to |
216 | six years to finally fire. |
217 | fire "after" a second might actually take six years to finally fire. |
217 | |
218 | |
218 | AnyEvent cannot compensate for this. The only event loop that is conscious |
219 | AnyEvent cannot compensate for this. The only event loop that is conscious |
219 | about these issues is L<EV>, which offers both relative (ev_timer) and |
220 | about these issues is L<EV>, which offers both relative (ev_timer, based |
220 | absolute (ev_periodic) timers. |
221 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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222 | timers. |
221 | |
223 | |
222 | AnyEvent always prefers relative timers, if available, matching the |
224 | AnyEvent always prefers relative timers, if available, matching the |
223 | AnyEvent API. |
225 | AnyEvent API. |
224 | |
226 | |
225 | =head2 SIGNAL WATCHERS |
227 | =head2 SIGNAL WATCHERS |
226 | |
228 | |
227 | You can watch for signals using a signal watcher, C<signal> is the signal |
229 | You can watch for signals using a signal watcher, C<signal> is the signal |
228 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
230 | I<name> without any C<SIG> prefix, C<cb> is the Perl callback to |
229 | be invoked whenever a signal occurs. |
231 | be invoked whenever a signal occurs. |
230 | |
232 | |
231 | Multiple signals occurances can be clumped together into one callback |
233 | Multiple signal occurances can be clumped together into one callback |
232 | invocation, and callback invocation will be synchronous. synchronous means |
234 | invocation, and callback invocation will be synchronous. synchronous means |
233 | that it might take a while until the signal gets handled by the process, |
235 | that it might take a while until the signal gets handled by the process, |
234 | but it is guarenteed not to interrupt any other callbacks. |
236 | but it is guarenteed not to interrupt any other callbacks. |
235 | |
237 | |
236 | The main advantage of using these watchers is that you can share a signal |
238 | The main advantage of using these watchers is that you can share a signal |
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361 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
363 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
362 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
364 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
363 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
365 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
364 | 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). |
365 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
367 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
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368 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
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369 | |
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370 | There is no support for WxWidgets, as WxWidgets has no support for |
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371 | watching file handles. However, you can use WxWidgets through the |
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372 | POE Adaptor, as POE has a Wx backend that simply polls 20 times per |
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373 | second, which was considered to be too horrible to even consider for |
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374 | AnyEvent. Likewise, other POE backends can be used by AnyEvent by using |
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375 | it's adaptor. |
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376 | |
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377 | AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when |
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378 | autodetecting them. |
366 | |
379 | |
367 | =item AnyEvent::detect |
380 | =item AnyEvent::detect |
368 | |
381 | |
369 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
382 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
370 | if necessary. You should only call this function right before you would |
383 | if necessary. You should only call this function right before you would |
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421 | no warnings; |
434 | no warnings; |
422 | use strict; |
435 | use strict; |
423 | |
436 | |
424 | use Carp; |
437 | use Carp; |
425 | |
438 | |
426 | our $VERSION = '3.12'; |
439 | our $VERSION = '3.3'; |
427 | our $MODEL; |
440 | our $MODEL; |
428 | |
441 | |
429 | our $AUTOLOAD; |
442 | our $AUTOLOAD; |
430 | our @ISA; |
443 | our @ISA; |
431 | |
444 | |
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438 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
451 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
439 | [EV:: => AnyEvent::Impl::EV::], |
452 | [EV:: => AnyEvent::Impl::EV::], |
440 | [Event:: => AnyEvent::Impl::Event::], |
453 | [Event:: => AnyEvent::Impl::Event::], |
441 | [Glib:: => AnyEvent::Impl::Glib::], |
454 | [Glib:: => AnyEvent::Impl::Glib::], |
442 | [Tk:: => AnyEvent::Impl::Tk::], |
455 | [Tk:: => AnyEvent::Impl::Tk::], |
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456 | [Wx:: => AnyEvent::Impl::POE::], |
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457 | [Prima:: => AnyEvent::Impl::POE::], |
443 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
458 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
444 | ); |
459 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
445 | my @models_detect = ( |
460 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
446 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
461 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
447 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
462 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
448 | ); |
463 | ); |
449 | |
464 | |
450 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
465 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
451 | |
466 | |
452 | sub detect() { |
467 | sub detect() { |
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456 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
471 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
457 | my $model = "AnyEvent::Impl::$1"; |
472 | my $model = "AnyEvent::Impl::$1"; |
458 | if (eval "require $model") { |
473 | if (eval "require $model") { |
459 | $MODEL = $model; |
474 | $MODEL = $model; |
460 | warn "AnyEvent: loaded model '$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 $verbose > 1; |
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476 | } else { |
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477 | warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose; |
461 | } |
478 | } |
462 | } |
479 | } |
463 | |
480 | |
464 | # check for already loaded models |
481 | # check for already loaded models |
465 | unless ($MODEL) { |
482 | unless ($MODEL) { |
466 | for (@REGISTRY, @models, @models_detect) { |
483 | for (@REGISTRY, @models) { |
467 | my ($package, $model) = @$_; |
484 | my ($package, $model) = @$_; |
468 | if (${"$package\::VERSION"} > 0) { |
485 | if (${"$package\::VERSION"} > 0) { |
469 | if (eval "require $model") { |
486 | if (eval "require $model") { |
470 | $MODEL = $model; |
487 | $MODEL = $model; |
471 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
488 | warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1; |
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658 | |
675 | |
659 | =over 4 |
676 | =over 4 |
660 | |
677 | |
661 | =item C<PERL_ANYEVENT_VERBOSE> |
678 | =item C<PERL_ANYEVENT_VERBOSE> |
662 | |
679 | |
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680 | By default, AnyEvent will be completely silent except in fatal |
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681 | conditions. You can set this environment variable to make AnyEvent more |
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682 | talkative. |
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683 | |
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684 | When set to C<1> or higher, causes AnyEvent to warn about unexpected |
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685 | conditions, such as not being able to load the event model specified by |
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686 | C<PERL_ANYEVENT_MODEL>. |
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687 | |
663 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
688 | When set to C<2> or higher, cause AnyEvent to report to STDERR which event |
664 | model it chooses. |
689 | model it chooses. |
665 | |
690 | |
666 | =item C<PERL_ANYEVENT_MODEL> |
691 | =item C<PERL_ANYEVENT_MODEL> |
667 | |
692 | |
… | |
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835 | $quit->broadcast; |
860 | $quit->broadcast; |
836 | }); |
861 | }); |
837 | |
862 | |
838 | $quit->wait; |
863 | $quit->wait; |
839 | |
864 | |
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865 | |
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866 | =head1 BENCHMARK |
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867 | |
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868 | To give you an idea of the performance and overheads that AnyEvent adds |
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869 | over the backends directly, here is a benchmark of various supported event |
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870 | models natively and with anyevent. The benchmark creates a lot of timers |
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871 | (with a zero timeout) and io watchers (watching STDOUT, a pty, to become |
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872 | writable), lets them fire exactly once and destroys them again. |
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873 | |
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874 | Explanation of the fields: |
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875 | |
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876 | I<watcher> is the number of event watchers created/destroyed. Sicne |
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877 | different event models have vastly different performance each backend was |
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878 | handed a number of watchers so that overall runtime is acceptable and |
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879 | similar to all backends (and keep them from crashing). |
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880 | |
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881 | I<bytes> is the number of bytes (as measured by resident set size) used by |
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882 | each watcher. |
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883 | |
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884 | I<create> is the time, in microseconds, to create a single watcher. |
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885 | |
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886 | I<invoke> is the time, in microseconds, used to invoke a simple callback |
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887 | that simply counts down. |
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888 | |
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889 | I<destroy> is the time, in microseconds, to destroy a single watcher. |
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890 | |
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891 | name watcher bytes create invoke destroy comment |
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892 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
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893 | EV/Any 100000 610 3.52 0.91 0.75 |
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894 | CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal |
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895 | Perl/Any 10000 654 4.64 1.22 0.77 pure perl implementation |
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896 | Event/Event 10000 523 28.05 21.38 5.22 Event native interface |
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897 | Event/Any 10000 943 34.43 20.48 1.39 |
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898 | Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour |
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899 | Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers |
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900 | POE/Select 2000 6343 94.69 807.65 562.69 POE::Loop::Select |
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901 | POE/Event 2000 6644 108.15 768.19 14.33 POE::Loop::Event |
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902 | |
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903 | Discussion: The benchmark does I<not> bench scalability of the |
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904 | backend. For example a select-based backend (such as the pureperl one) can |
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905 | never compete with a backend using epoll. In this benchmark, only a single |
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906 | filehandle is used. |
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907 | |
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908 | EV is the sole leader regarding speed and memory use, which are both |
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909 | maximal/minimal. Even when going through AnyEvent, there is only one event |
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910 | loop that uses less memory (the Event module natively), and no faster |
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911 | event model. |
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912 | |
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913 | The pure perl implementation is hit in a few sweet spots (both the |
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914 | zero timeout and the use of a single fd hit optimisations in the perl |
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915 | interpreter and the backend itself), but it shows that it adds very little |
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916 | overhead in itself. Like any select-based backend it's performance becomes |
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917 | really bad with lots of file descriptors. |
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918 | |
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919 | The Event module has a relatively high setup and callback invocation cost, |
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920 | but overall scores on the third place. |
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921 | |
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922 | Glib has a little higher memory cost, a bit fster callback invocation and |
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923 | has a similar speed as Event. |
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924 | |
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925 | The Tk backend works relatively well, the fact that it crashes with |
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926 | more than 2000 watchers is a big setback, however, as correctness takes |
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927 | precedence over speed. |
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928 | |
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929 | POE, regardless of backend (wether it's pure perl select backend or the |
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930 | Event backend) shows abysmal performance and memory usage: Watchers use |
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931 | almost 30 times as much memory as EV watchers, and 10 times as much memory |
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932 | as both Event or EV via AnyEvent. |
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933 | |
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934 | Summary: using EV through AnyEvent is faster than any other event |
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935 | loop. The overhead AnyEvent adds can be very small, and you should avoid |
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936 | POE like the plague if you want performance or reasonable memory usage. |
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937 | |
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938 | |
840 | =head1 FORK |
939 | =head1 FORK |
841 | |
940 | |
842 | Most event libraries are not fork-safe. The ones who are usually are |
941 | Most event libraries are not fork-safe. The ones who are usually are |
843 | because they are so inefficient. Only L<EV> is fully fork-aware. |
942 | because they are so inefficient. Only L<EV> is fully fork-aware. |
844 | |
943 | |
845 | If you have to fork, you must either do so I<before> creating your first |
944 | If you have to fork, you must either do so I<before> creating your first |
846 | watcher OR you must not use AnyEvent at all in the child. |
945 | watcher OR you must not use AnyEvent at all in the child. |
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946 | |
847 | |
947 | |
848 | =head1 SECURITY CONSIDERATIONS |
948 | =head1 SECURITY CONSIDERATIONS |
849 | |
949 | |
850 | AnyEvent can be forced to load any event model via |
950 | AnyEvent can be forced to load any event model via |
851 | $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 |
… | |
… | |
859 | |
959 | |
860 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
960 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
861 | |
961 | |
862 | use AnyEvent; |
962 | use AnyEvent; |
863 | |
963 | |
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964 | |
864 | =head1 SEE ALSO |
965 | =head1 SEE ALSO |
865 | |
966 | |
866 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
967 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
867 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
968 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
868 | L<Event::Lib>, L<Qt>. |
969 | L<Event::Lib>, L<Qt>, L<POE>. |
869 | |
970 | |
870 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
971 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
871 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
972 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
872 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
973 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
873 | L<AnyEvent::Impl::Qt>. |
974 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
874 | |
975 | |
875 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
976 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
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977 | |
876 | |
978 | |
877 | =head1 AUTHOR |
979 | =head1 AUTHOR |
878 | |
980 | |
879 | Marc Lehmann <schmorp@schmorp.de> |
981 | Marc Lehmann <schmorp@schmorp.de> |
880 | http://home.schmorp.de/ |
982 | http://home.schmorp.de/ |