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 - 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 | |
… | |
… | |
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 the |
83 | to detect the currently loaded event loop by probing whether one of the |
84 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
84 | following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>, |
85 | L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found, |
85 | L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>, |
86 | the module tries to load these modules in the stated order. The first one |
86 | L<POE>. The first one found is used. If none are found, the module tries |
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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 |
87 | that can be successfully loaded will be used. If, after this, still none |
89 | be successfully loaded will be used. If, after this, still none could be |
88 | could be found, AnyEvent will fall back to a pure-perl event loop, which |
90 | found, AnyEvent will fall back to a pure-perl event loop, which is not |
89 | is not very efficient, but should work everywhere. |
91 | very efficient, but should work everywhere. |
90 | |
92 | |
91 | Because AnyEvent first checks for modules that are already loaded, loading |
93 | Because AnyEvent first checks for modules that are already loaded, loading |
92 | an event model explicitly before first using AnyEvent will likely make |
94 | an event model explicitly before first using AnyEvent will likely make |
93 | that model the default. For example: |
95 | that model the default. For example: |
94 | |
96 | |
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145 | events. C<poll> must be a string that is either C<r> or C<w>, which |
147 | events. C<poll> must be a string that is either C<r> or C<w>, which |
146 | creates a watcher waiting for "r"eadable or "w"ritable events, |
148 | creates a watcher waiting for "r"eadable or "w"ritable events, |
147 | respectively. C<cb> is the callback to invoke each time the file handle |
149 | respectively. C<cb> is the callback to invoke each time the file handle |
148 | becomes ready. |
150 | becomes ready. |
149 | |
151 | |
150 | File handles will be kept alive, so as long as the watcher exists, the |
152 | As long as the I/O watcher exists it will keep the file descriptor or a |
151 | file handle exists, too. |
153 | copy of it alive/open. |
152 | |
154 | |
153 | It is not allowed to close a file handle as long as any watcher is active |
155 | It is not allowed to close a file handle as long as any watcher is active |
154 | on the underlying file descriptor. |
156 | on the underlying file descriptor. |
155 | |
157 | |
156 | Some event loops issue spurious readyness notifications, so you should |
158 | Some event loops issue spurious readyness notifications, so you should |
… | |
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206 | |
208 | |
207 | 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 |
208 | 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 |
209 | o'clock"). |
211 | o'clock"). |
210 | |
212 | |
211 | 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 |
212 | absolute time internally. This makes a difference when your clock "jumps", |
214 | use absolute time internally. This makes a difference when your clock |
213 | 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 |
214 | 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 |
215 | six years to finally fire. |
217 | fire "after" a second might actually take six years to finally fire. |
216 | |
218 | |
217 | 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 |
218 | 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 |
219 | absolute (ev_periodic) timers. |
221 | on true relative time) and absolute (ev_periodic, based on wallclock time) |
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222 | timers. |
220 | |
223 | |
221 | AnyEvent always prefers relative timers, if available, matching the |
224 | AnyEvent always prefers relative timers, if available, matching the |
222 | AnyEvent API. |
225 | AnyEvent API. |
223 | |
226 | |
224 | =head2 SIGNAL WATCHERS |
227 | =head2 SIGNAL WATCHERS |
225 | |
228 | |
226 | 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 |
227 | 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 |
228 | be invoked whenever a signal occurs. |
231 | be invoked whenever a signal occurs. |
229 | |
232 | |
230 | Multiple signals occurances can be clumped together into one callback |
233 | Multiple signal occurances can be clumped together into one callback |
231 | invocation, and callback invocation will be synchronous. synchronous means |
234 | invocation, and callback invocation will be synchronous. synchronous means |
232 | 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, |
233 | but it is guarenteed not to interrupt any other callbacks. |
236 | but it is guarenteed not to interrupt any other callbacks. |
234 | |
237 | |
235 | 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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353 | |
356 | |
354 | The known classes so far are: |
357 | The known classes so far are: |
355 | |
358 | |
356 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
359 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
357 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
360 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
358 | AnyEvent::Impl::EV based on EV (an interface to libev, also best choice). |
361 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
359 | AnyEvent::Impl::Event based on Event, also second best choice :) |
362 | AnyEvent::Impl::Event based on Event, second best choice. |
360 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
363 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
361 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
364 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
362 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
365 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
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366 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
363 | 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. |
364 | |
379 | |
365 | =item AnyEvent::detect |
380 | =item AnyEvent::detect |
366 | |
381 | |
367 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
382 | Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model |
368 | 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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419 | no warnings; |
434 | no warnings; |
420 | use strict; |
435 | use strict; |
421 | |
436 | |
422 | use Carp; |
437 | use Carp; |
423 | |
438 | |
424 | our $VERSION = '3.12'; |
439 | our $VERSION = '3.3'; |
425 | our $MODEL; |
440 | our $MODEL; |
426 | |
441 | |
427 | our $AUTOLOAD; |
442 | our $AUTOLOAD; |
428 | our @ISA; |
443 | our @ISA; |
429 | |
444 | |
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436 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
451 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
437 | [EV:: => AnyEvent::Impl::EV::], |
452 | [EV:: => AnyEvent::Impl::EV::], |
438 | [Event:: => AnyEvent::Impl::Event::], |
453 | [Event:: => AnyEvent::Impl::Event::], |
439 | [Glib:: => AnyEvent::Impl::Glib::], |
454 | [Glib:: => AnyEvent::Impl::Glib::], |
440 | [Tk:: => AnyEvent::Impl::Tk::], |
455 | [Tk:: => AnyEvent::Impl::Tk::], |
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456 | [Wx:: => AnyEvent::Impl::POE::], |
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457 | [Prima:: => AnyEvent::Impl::POE::], |
441 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
458 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
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459 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
442 | [Event::Lib:: => AnyEvent::Impl::EventLib::], |
460 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
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461 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
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462 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
443 | ); |
463 | ); |
444 | |
464 | |
445 | our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY); |
465 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
446 | |
466 | |
447 | sub detect() { |
467 | sub detect() { |
448 | unless ($MODEL) { |
468 | unless ($MODEL) { |
449 | no strict 'refs'; |
469 | no strict 'refs'; |
450 | |
470 | |
451 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
471 | if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { |
452 | my $model = "AnyEvent::Impl::$1"; |
472 | my $model = "AnyEvent::Impl::$1"; |
453 | if (eval "require $model") { |
473 | if (eval "require $model") { |
454 | $MODEL = $model; |
474 | $MODEL = $model; |
455 | warn "AnyEvent: loaded model '$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 $verbose; |
456 | } |
478 | } |
457 | } |
479 | } |
458 | |
480 | |
459 | # check for already loaded models |
481 | # check for already loaded models |
460 | unless ($MODEL) { |
482 | unless ($MODEL) { |
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653 | |
675 | |
654 | =over 4 |
676 | =over 4 |
655 | |
677 | |
656 | =item C<PERL_ANYEVENT_VERBOSE> |
678 | =item C<PERL_ANYEVENT_VERBOSE> |
657 | |
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 | |
658 | 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 |
659 | model it chooses. |
689 | model it chooses. |
660 | |
690 | |
661 | =item C<PERL_ANYEVENT_MODEL> |
691 | =item C<PERL_ANYEVENT_MODEL> |
662 | |
692 | |
… | |
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830 | $quit->broadcast; |
860 | $quit->broadcast; |
831 | }); |
861 | }); |
832 | |
862 | |
833 | $quit->wait; |
863 | $quit->wait; |
834 | |
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, which it is), lets them fire exactly once and destroys them |
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873 | again. |
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874 | |
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875 | Explanation of the fields: |
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876 | |
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877 | I<watcher> is the number of event watchers created/destroyed. Sicne |
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878 | different event models have vastly different performance each backend was |
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879 | handed a number of watchers so that overall runtime is acceptable and |
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880 | similar to all backends (and keep them from crashing). |
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881 | |
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882 | I<bytes> is the number of bytes (as measured by resident set size) used by |
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883 | each watcher. |
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884 | |
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885 | I<create> is the time, in microseconds, to create a single watcher. |
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886 | |
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887 | I<invoke> is the time, in microseconds, used to invoke a simple callback |
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888 | that simply counts down. |
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889 | |
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890 | I<destroy> is the time, in microseconds, to destroy a single watcher. |
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891 | |
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892 | name watcher bytes create invoke destroy comment |
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893 | EV/EV 400000 244 0.56 0.46 0.31 EV native interface |
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894 | EV/Any 100000 610 3.52 0.91 0.75 |
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895 | CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal |
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896 | Perl/Any 10000 654 4.64 1.22 0.77 pure perl implementation |
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897 | Event/Event 10000 523 28.05 21.38 5.22 Event native interface |
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898 | Event/Any 10000 943 34.43 20.48 1.39 |
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899 | Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour |
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900 | Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers |
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901 | POE/Select 2000 6343 94.69 807.65 562.69 POE::Loop::Select |
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902 | POE/Event 2000 6644 108.15 768.19 14.33 POE::Loop::Event |
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903 | |
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904 | Discussion: The benchmark does I<not> bench scalability of the |
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905 | backend. For example a select-based backend (such as the pureperl one) can |
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906 | never compete with a backend using epoll. In this benchmark, only a single |
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907 | filehandle is used. |
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908 | |
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909 | EV is the sole leader regarding speed and memory use, which are both |
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910 | maximal/minimal. Even when going through AnyEvent, there is only one event |
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911 | loop that uses less memory (the Event module natively), and no faster |
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912 | event model. |
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913 | |
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914 | The pure perl implementation is hit in a few sweet spots (both the |
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915 | zero timeout and the use of a single fd hit optimisations in the perl |
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916 | interpreter and the backend itself), but it shows that it adds very little |
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917 | overhead in itself. Like any select-based backend it's performance becomes |
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918 | really bad with lots of file descriptors. |
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919 | |
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920 | The Event module has a relatively high setup and callback invocation cost, |
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921 | but overall scores on the third place. |
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922 | |
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923 | Glib has a little higher memory cost, a bit fster callback invocation and |
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924 | has a similar speed as Event. |
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925 | |
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926 | The Tk backend works relatively well, the fact that it crashes with |
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927 | more than 2000 watchers is a big setback, however, as correctness takes |
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928 | precedence over speed. |
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929 | |
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930 | POE, regardless of backend (wether it's pure perl select backend or the |
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931 | Event backend) shows abysmal performance and memory usage: Watchers use |
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932 | almost 30 times as much memory as EV watchers, and 10 times as much memory |
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933 | as both Event or EV via AnyEvent. |
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934 | |
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935 | Summary: using EV through AnyEvent is faster than any other event |
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936 | loop. The overhead AnyEvent adds can be very small, and you should avoid |
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937 | POE like the plague if you want performance or reasonable memory usage. |
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938 | |
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939 | |
835 | =head1 FORK |
940 | =head1 FORK |
836 | |
941 | |
837 | Most event libraries are not fork-safe. The ones who are usually are |
942 | Most event libraries are not fork-safe. The ones who are usually are |
838 | because they are so inefficient. Only L<EV> is fully fork-aware. |
943 | because they are so inefficient. Only L<EV> is fully fork-aware. |
839 | |
944 | |
840 | If you have to fork, you must either do so I<before> creating your first |
945 | If you have to fork, you must either do so I<before> creating your first |
841 | watcher OR you must not use AnyEvent at all in the child. |
946 | watcher OR you must not use AnyEvent at all in the child. |
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947 | |
842 | |
948 | |
843 | =head1 SECURITY CONSIDERATIONS |
949 | =head1 SECURITY CONSIDERATIONS |
844 | |
950 | |
845 | AnyEvent can be forced to load any event model via |
951 | AnyEvent can be forced to load any event model via |
846 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
952 | $ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to |
… | |
… | |
854 | |
960 | |
855 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
961 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
856 | |
962 | |
857 | use AnyEvent; |
963 | use AnyEvent; |
858 | |
964 | |
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965 | |
859 | =head1 SEE ALSO |
966 | =head1 SEE ALSO |
860 | |
967 | |
861 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
968 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
862 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
969 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
863 | L<Event::Lib>. |
970 | L<Event::Lib>, L<Qt>, L<POE>. |
864 | |
971 | |
865 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
972 | Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>, |
866 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
973 | L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, |
867 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>. |
974 | L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>, |
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975 | L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>. |
868 | |
976 | |
869 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
977 | Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. |
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978 | |
870 | |
979 | |
871 | =head1 AUTHOR |
980 | =head1 AUTHOR |
872 | |
981 | |
873 | Marc Lehmann <schmorp@schmorp.de> |
982 | Marc Lehmann <schmorp@schmorp.de> |
874 | http://home.schmorp.de/ |
983 | http://home.schmorp.de/ |