… | |
… | |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
15 | my $w = AnyEvent->timer (after => $seconds, cb => sub { |
16 | ... |
16 | ... |
17 | }); |
17 | }); |
18 | |
18 | |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
19 | my $w = AnyEvent->condvar; # stores whether a condition was flagged |
20 | $w->wait; # enters "main loop" till $condvar gets ->broadcast |
20 | $w->wait; # enters "main loop" till $condvar gets ->send |
21 | $w->broadcast; # wake up current and all future wait's |
21 | $w->send; # wake up current and all future wait's |
22 | |
22 | |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
23 | =head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) |
24 | |
24 | |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
25 | Glib, POE, IO::Async, Event... CPAN offers event models by the dozen |
26 | nowadays. So what is different about AnyEvent? |
26 | nowadays. So what is different about AnyEvent? |
… | |
… | |
288 | my $w = AnyEvent->child ( |
288 | my $w = AnyEvent->child ( |
289 | pid => $pid, |
289 | pid => $pid, |
290 | cb => sub { |
290 | cb => sub { |
291 | my ($pid, $status) = @_; |
291 | my ($pid, $status) = @_; |
292 | warn "pid $pid exited with status $status"; |
292 | warn "pid $pid exited with status $status"; |
293 | $done->broadcast; |
293 | $done->send; |
294 | }, |
294 | }, |
295 | ); |
295 | ); |
296 | |
296 | |
297 | # do something else, then wait for process exit |
297 | # do something else, then wait for process exit |
298 | $done->wait; |
298 | $done->wait; |
299 | |
299 | |
300 | =head2 CONDITION VARIABLES |
300 | =head2 CONDITION VARIABLES |
301 | |
301 | |
|
|
302 | If you are familiar with some event loops you will know that all of them |
|
|
303 | require you to run some blocking "loop", "run" or similar function that |
|
|
304 | will actively watch for new events and call your callbacks. |
|
|
305 | |
|
|
306 | AnyEvent is different, it expects somebody else to run the event loop and |
|
|
307 | will only block when necessary (usually when told by the user). |
|
|
308 | |
|
|
309 | The instrument to do that is called a "condition variable", so called |
|
|
310 | because they represent a condition that must become true. |
|
|
311 | |
302 | Condition variables can be created by calling the C<< AnyEvent->condvar >> |
312 | Condition variables can be created by calling the C<< AnyEvent->condvar |
303 | method without any arguments. |
313 | >> method, usually without arguments. The only argument pair allowed is |
|
|
314 | C<cb>, which specifies a callback to be called when the condition variable |
|
|
315 | becomes true. |
304 | |
316 | |
305 | A condition variable waits for a condition - precisely that the C<< |
317 | After creation, the conditon variable is "false" until it becomes "true" |
306 | ->broadcast >> method has been called. |
318 | by calling the C<send> method. |
307 | |
319 | |
308 | They are very useful to signal that a condition has been fulfilled, for |
320 | Condition variables are similar to callbacks, except that you can |
|
|
321 | optionally wait for them. They can also be called merge points - points |
|
|
322 | in time where multiple outstandign events have been processed. And yet |
|
|
323 | another way to call them is transations - each condition variable can be |
|
|
324 | used to represent a transaction, which finishes at some point and delivers |
|
|
325 | a result. |
|
|
326 | |
|
|
327 | Condition variables are very useful to signal that something has finished, |
309 | example, if you write a module that does asynchronous http requests, |
328 | for example, if you write a module that does asynchronous http requests, |
310 | then a condition variable would be the ideal candidate to signal the |
329 | then a condition variable would be the ideal candidate to signal the |
311 | availability of results. |
330 | availability of results. The user can either act when the callback is |
|
|
331 | called or can synchronously C<< ->wait >> for the results. |
312 | |
332 | |
313 | You can also use condition variables to block your main program until |
333 | You can also use them to simulate traditional event loops - for example, |
314 | an event occurs - for example, you could C<< ->wait >> in your main |
334 | you can block your main program until an event occurs - for example, you |
315 | program until the user clicks the Quit button in your app, which would C<< |
335 | could C<< ->wait >> in your main program until the user clicks the Quit |
316 | ->broadcast >> the "quit" event. |
336 | button of your app, which would C<< ->send >> the "quit" event. |
317 | |
337 | |
318 | Note that condition variables recurse into the event loop - if you have |
338 | Note that condition variables recurse into the event loop - if you have |
319 | two pirces of code that call C<< ->wait >> in a round-robbin fashion, you |
339 | two pieces of code that call C<< ->wait >> in a round-robbin fashion, you |
320 | lose. Therefore, condition variables are good to export to your caller, but |
340 | lose. Therefore, condition variables are good to export to your caller, but |
321 | you should avoid making a blocking wait yourself, at least in callbacks, |
341 | you should avoid making a blocking wait yourself, at least in callbacks, |
322 | as this asks for trouble. |
342 | as this asks for trouble. |
323 | |
343 | |
324 | This object has two methods: |
344 | Condition variables are represented by hash refs in perl, and the keys |
|
|
345 | used by AnyEvent itself are all named C<_ae_XXX> to make subclassing |
|
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346 | easy (it is often useful to build your own transaction class on top of |
|
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347 | AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call |
|
|
348 | it's C<new> method in your own C<new> method. |
|
|
349 | |
|
|
350 | There are two "sides" to a condition variable - the "producer side" which |
|
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351 | eventually calls C<< -> send >>, and the "consumer side", which waits |
|
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352 | for the send to occur. |
|
|
353 | |
|
|
354 | Example: |
|
|
355 | |
|
|
356 | # wait till the result is ready |
|
|
357 | my $result_ready = AnyEvent->condvar; |
|
|
358 | |
|
|
359 | # do something such as adding a timer |
|
|
360 | # or socket watcher the calls $result_ready->send |
|
|
361 | # when the "result" is ready. |
|
|
362 | # in this case, we simply use a timer: |
|
|
363 | my $w = AnyEvent->timer ( |
|
|
364 | after => 1, |
|
|
365 | cb => sub { $result_ready->send }, |
|
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366 | ); |
|
|
367 | |
|
|
368 | # this "blocks" (while handling events) till the callback |
|
|
369 | # calls send |
|
|
370 | $result_ready->wait; |
|
|
371 | |
|
|
372 | =head3 METHODS FOR PRODUCERS |
|
|
373 | |
|
|
374 | These methods should only be used by the producing side, i.e. the |
|
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375 | code/module that eventually sends the signal. Note that it is also |
|
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376 | the producer side which creates the condvar in most cases, but it isn't |
|
|
377 | uncommon for the consumer to create it as well. |
325 | |
378 | |
326 | =over 4 |
379 | =over 4 |
327 | |
380 | |
|
|
381 | =item $cv->send (...) |
|
|
382 | |
|
|
383 | Flag the condition as ready - a running C<< ->wait >> and all further |
|
|
384 | calls to C<wait> will (eventually) return after this method has been |
|
|
385 | called. If nobody is waiting the send will be remembered. |
|
|
386 | |
|
|
387 | If a callback has been set on the condition variable, it is called |
|
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388 | immediately from within send. |
|
|
389 | |
|
|
390 | Any arguments passed to the C<send> call will be returned by all |
|
|
391 | future C<< ->wait >> calls. |
|
|
392 | |
|
|
393 | =item $cv->croak ($error) |
|
|
394 | |
|
|
395 | Similar to send, but causes all call's wait C<< ->wait >> to invoke |
|
|
396 | C<Carp::croak> with the given error message/object/scalar. |
|
|
397 | |
|
|
398 | This can be used to signal any errors to the condition variable |
|
|
399 | user/consumer. |
|
|
400 | |
|
|
401 | =item $cv->begin ([group callback]) |
|
|
402 | |
|
|
403 | =item $cv->end |
|
|
404 | |
|
|
405 | These two methods can be used to combine many transactions/events into |
|
|
406 | one. For example, a function that pings many hosts in parallel might want |
|
|
407 | to use a condition variable for the whole process. |
|
|
408 | |
|
|
409 | Every call to C<< ->begin >> will increment a counter, and every call to |
|
|
410 | C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end |
|
|
411 | >>, the (last) callback passed to C<begin> will be executed. That callback |
|
|
412 | is I<supposed> to call C<< ->send >>, but that is not required. If no |
|
|
413 | callback was set, C<send> will be called without any arguments. |
|
|
414 | |
|
|
415 | Let's clarify this with the ping example: |
|
|
416 | |
|
|
417 | my $cv = AnyEvent->condvar; |
|
|
418 | |
|
|
419 | my %result; |
|
|
420 | $cv->begin (sub { $cv->send (\%result) }); |
|
|
421 | |
|
|
422 | for my $host (@list_of_hosts) { |
|
|
423 | $cv->begin; |
|
|
424 | ping_host_then_call_callback $host, sub { |
|
|
425 | $result{$host} = ...; |
|
|
426 | $cv->end; |
|
|
427 | }; |
|
|
428 | } |
|
|
429 | |
|
|
430 | $cv->end; |
|
|
431 | |
|
|
432 | This code fragment supposedly pings a number of hosts and calls |
|
|
433 | C<send> after results for all then have have been gathered - in any |
|
|
434 | order. To achieve this, the code issues a call to C<begin> when it starts |
|
|
435 | each ping request and calls C<end> when it has received some result for |
|
|
436 | it. Since C<begin> and C<end> only maintain a counter, the order in which |
|
|
437 | results arrive is not relevant. |
|
|
438 | |
|
|
439 | There is an additional bracketing call to C<begin> and C<end> outside the |
|
|
440 | loop, which serves two important purposes: first, it sets the callback |
|
|
441 | to be called once the counter reaches C<0>, and second, it ensures that |
|
|
442 | C<send> is called even when C<no> hosts are being pinged (the loop |
|
|
443 | doesn't execute once). |
|
|
444 | |
|
|
445 | This is the general pattern when you "fan out" into multiple subrequests: |
|
|
446 | use an outer C<begin>/C<end> pair to set the callback and ensure C<end> |
|
|
447 | is called at least once, and then, for each subrequest you start, call |
|
|
448 | C<begin> and for eahc subrequest you finish, call C<end>. |
|
|
449 | |
|
|
450 | =back |
|
|
451 | |
|
|
452 | =head3 METHODS FOR CONSUMERS |
|
|
453 | |
|
|
454 | These methods should only be used by the consuming side, i.e. the |
|
|
455 | code awaits the condition. |
|
|
456 | |
|
|
457 | =over 4 |
|
|
458 | |
328 | =item $cv->wait |
459 | =item $cv->wait |
329 | |
460 | |
330 | Wait (blocking if necessary) until the C<< ->broadcast >> method has been |
461 | Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak |
331 | called on c<$cv>, while servicing other watchers normally. |
462 | >> methods have been called on c<$cv>, while servicing other watchers |
|
|
463 | normally. |
332 | |
464 | |
333 | You can only wait once on a condition - additional calls will return |
465 | You can only wait once on a condition - additional calls are valid but |
334 | immediately. |
466 | will return immediately. |
|
|
467 | |
|
|
468 | If an error condition has been set by calling C<< ->croak >>, then this |
|
|
469 | function will call C<croak>. |
|
|
470 | |
|
|
471 | In list context, all parameters passed to C<send> will be returned, |
|
|
472 | in scalar context only the first one will be returned. |
335 | |
473 | |
336 | Not all event models support a blocking wait - some die in that case |
474 | Not all event models support a blocking wait - some die in that case |
337 | (programs might want to do that to stay interactive), so I<if you are |
475 | (programs might want to do that to stay interactive), so I<if you are |
338 | using this from a module, never require a blocking wait>, but let the |
476 | using this from a module, never require a blocking wait>, but let the |
339 | caller decide whether the call will block or not (for example, by coupling |
477 | caller decide whether the call will block or not (for example, by coupling |
… | |
… | |
346 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
484 | multiple interpreters or coroutines/threads, none of which C<AnyEvent> |
347 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
485 | can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and |
348 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
486 | L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s |
349 | from different coroutines, however). |
487 | from different coroutines, however). |
350 | |
488 | |
351 | =item $cv->broadcast |
489 | You can ensure that C<< -wait >> never blocks by setting a callback and |
|
|
490 | only calling C<< ->wait >> from within that callback (or at a later |
|
|
491 | time). This will work even when the event loop does not support blocking |
|
|
492 | waits otherwise. |
352 | |
493 | |
353 | Flag the condition as ready - a running C<< ->wait >> and all further |
494 | =item $bool = $cv->ready |
354 | calls to C<wait> will (eventually) return after this method has been |
495 | |
355 | called. If nobody is waiting the broadcast will be remembered.. |
496 | Returns true when the condition is "true", i.e. whether C<send> or |
|
|
497 | C<croak> have been called. |
|
|
498 | |
|
|
499 | =item $cb = $cv->cb ([new callback]) |
|
|
500 | |
|
|
501 | This is a mutator function that returns the callback set and optionally |
|
|
502 | replaces it before doing so. |
|
|
503 | |
|
|
504 | The callback will be called when the condition becomes "true", i.e. when |
|
|
505 | C<send> or C<croak> are called. Calling C<wait> inside the callback |
|
|
506 | or at any later time is guaranteed not to block. |
356 | |
507 | |
357 | =back |
508 | =back |
358 | |
|
|
359 | Example: |
|
|
360 | |
|
|
361 | # wait till the result is ready |
|
|
362 | my $result_ready = AnyEvent->condvar; |
|
|
363 | |
|
|
364 | # do something such as adding a timer |
|
|
365 | # or socket watcher the calls $result_ready->broadcast |
|
|
366 | # when the "result" is ready. |
|
|
367 | # in this case, we simply use a timer: |
|
|
368 | my $w = AnyEvent->timer ( |
|
|
369 | after => 1, |
|
|
370 | cb => sub { $result_ready->broadcast }, |
|
|
371 | ); |
|
|
372 | |
|
|
373 | # this "blocks" (while handling events) till the watcher |
|
|
374 | # calls broadcast |
|
|
375 | $result_ready->wait; |
|
|
376 | |
509 | |
377 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
510 | =head1 GLOBAL VARIABLES AND FUNCTIONS |
378 | |
511 | |
379 | =over 4 |
512 | =over 4 |
380 | |
513 | |
… | |
… | |
390 | |
523 | |
391 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
524 | AnyEvent::Impl::CoroEV based on Coro::EV, best choice. |
392 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
525 | AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. |
393 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
526 | AnyEvent::Impl::EV based on EV (an interface to libev, best choice). |
394 | AnyEvent::Impl::Event based on Event, second best choice. |
527 | AnyEvent::Impl::Event based on Event, second best choice. |
|
|
528 | AnyEvent::Impl::Perl pure-perl implementation, fast and portable. |
395 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
529 | AnyEvent::Impl::Glib based on Glib, third-best choice. |
396 | AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. |
|
|
397 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
530 | AnyEvent::Impl::Tk based on Tk, very bad choice. |
398 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
531 | AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). |
399 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
532 | AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. |
400 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
533 | AnyEvent::Impl::POE based on POE, not generic enough for full support. |
401 | |
534 | |
… | |
… | |
427 | decide which event module to use as soon as the first method is called, so |
560 | decide which event module to use as soon as the first method is called, so |
428 | by calling AnyEvent in your module body you force the user of your module |
561 | by calling AnyEvent in your module body you force the user of your module |
429 | to load the event module first. |
562 | to load the event module first. |
430 | |
563 | |
431 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
564 | Never call C<< ->wait >> on a condition variable unless you I<know> that |
432 | the C<< ->broadcast >> method has been called on it already. This is |
565 | the C<< ->send >> method has been called on it already. This is |
433 | because it will stall the whole program, and the whole point of using |
566 | because it will stall the whole program, and the whole point of using |
434 | events is to stay interactive. |
567 | events is to stay interactive. |
435 | |
568 | |
436 | It is fine, however, to call C<< ->wait >> when the user of your module |
569 | It is fine, however, to call C<< ->wait >> when the user of your module |
437 | requests it (i.e. if you create a http request object ad have a method |
570 | requests it (i.e. if you create a http request object ad have a method |
… | |
… | |
553 | my @models = ( |
686 | my @models = ( |
554 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
687 | [Coro::EV:: => AnyEvent::Impl::CoroEV::], |
555 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
688 | [Coro::Event:: => AnyEvent::Impl::CoroEvent::], |
556 | [EV:: => AnyEvent::Impl::EV::], |
689 | [EV:: => AnyEvent::Impl::EV::], |
557 | [Event:: => AnyEvent::Impl::Event::], |
690 | [Event:: => AnyEvent::Impl::Event::], |
558 | [Glib:: => AnyEvent::Impl::Glib::], |
|
|
559 | [Tk:: => AnyEvent::Impl::Tk::], |
691 | [Tk:: => AnyEvent::Impl::Tk::], |
560 | [Wx:: => AnyEvent::Impl::POE::], |
692 | [Wx:: => AnyEvent::Impl::POE::], |
561 | [Prima:: => AnyEvent::Impl::POE::], |
693 | [Prima:: => AnyEvent::Impl::POE::], |
562 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
694 | [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], |
563 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
695 | # everything below here will not be autoprobed as the pureperl backend should work everywhere |
|
|
696 | [Glib:: => AnyEvent::Impl::Glib::], |
564 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
697 | [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy |
565 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
698 | [Qt:: => AnyEvent::Impl::Qt::], # requires special main program |
566 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
699 | [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza |
567 | ); |
700 | ); |
568 | |
701 | |
569 | our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY); |
702 | our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); |
570 | |
703 | |
571 | sub detect() { |
704 | sub detect() { |
572 | unless ($MODEL) { |
705 | unless ($MODEL) { |
573 | no strict 'refs'; |
706 | no strict 'refs'; |
574 | |
707 | |
… | |
… | |
1071 | file descriptor is dup()ed for each watcher. This shows that the dup() |
1204 | file descriptor is dup()ed for each watcher. This shows that the dup() |
1072 | employed by some adaptors is not a big performance issue (it does incur a |
1205 | employed by some adaptors is not a big performance issue (it does incur a |
1073 | hidden memory cost inside the kernel which is not reflected in the figures |
1206 | hidden memory cost inside the kernel which is not reflected in the figures |
1074 | above). |
1207 | above). |
1075 | |
1208 | |
1076 | C<POE>, regardless of underlying event loop (whether using its pure |
1209 | C<POE>, regardless of underlying event loop (whether using its pure perl |
1077 | perl select-based backend or the Event module, the POE-EV backend |
1210 | select-based backend or the Event module, the POE-EV backend couldn't |
1078 | couldn't be tested because it wasn't working) shows abysmal performance |
1211 | be tested because it wasn't working) shows abysmal performance and |
1079 | and memory usage: Watchers use almost 30 times as much memory as |
1212 | memory usage with AnyEvent: Watchers use almost 30 times as much memory |
1080 | EV watchers, and 10 times as much memory as Event (the high memory |
1213 | as EV watchers, and 10 times as much memory as Event (the high memory |
1081 | requirements are caused by requiring a session for each watcher). Watcher |
1214 | requirements are caused by requiring a session for each watcher). Watcher |
1082 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
1215 | invocation speed is almost 900 times slower than with AnyEvent's pure perl |
|
|
1216 | implementation. |
|
|
1217 | |
1083 | implementation. The design of the POE adaptor class in AnyEvent can not |
1218 | The design of the POE adaptor class in AnyEvent can not really account |
1084 | really account for this, as session creation overhead is small compared |
1219 | for the performance issues, though, as session creation overhead is |
1085 | to execution of the state machine, which is coded pretty optimally within |
1220 | small compared to execution of the state machine, which is coded pretty |
1086 | L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow. |
1221 | optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that |
|
|
1222 | using multiple sessions is not a good approach, especially regarding |
|
|
1223 | memory usage, even the author of POE could not come up with a faster |
|
|
1224 | design). |
1087 | |
1225 | |
1088 | =head3 Summary |
1226 | =head3 Summary |
1089 | |
1227 | |
1090 | =over 4 |
1228 | =over 4 |
1091 | |
1229 | |
… | |
… | |
1170 | |
1308 | |
1171 | =head3 Summary |
1309 | =head3 Summary |
1172 | |
1310 | |
1173 | =over 4 |
1311 | =over 4 |
1174 | |
1312 | |
1175 | =item * The pure perl implementation performs extremely well, considering |
1313 | =item * The pure perl implementation performs extremely well. |
1176 | that it uses select. |
|
|
1177 | |
1314 | |
1178 | =item * Avoid Glib or POE in large projects where performance matters. |
1315 | =item * Avoid Glib or POE in large projects where performance matters. |
1179 | |
1316 | |
1180 | =back |
1317 | =back |
1181 | |
1318 | |
… | |
… | |
1210 | speed most when you have lots of watchers, not when you only have a few of |
1347 | speed most when you have lots of watchers, not when you only have a few of |
1211 | them). |
1348 | them). |
1212 | |
1349 | |
1213 | EV is again fastest. |
1350 | EV is again fastest. |
1214 | |
1351 | |
1215 | The C-based event loops Event and Glib come in second this time, as the |
1352 | Perl again comes second. It is noticably faster than the C-based event |
1216 | overhead of running an iteration is much smaller in C than in Perl (little |
1353 | loops Event and Glib, although the difference is too small to really |
1217 | code to execute in the inner loop, and perl's function calling overhead is |
1354 | matter. |
1218 | high, and updating all the data structures is costly). |
|
|
1219 | |
|
|
1220 | The pure perl event loop is much slower, but still competitive. |
|
|
1221 | |
1355 | |
1222 | POE also performs much better in this case, but is is still far behind the |
1356 | POE also performs much better in this case, but is is still far behind the |
1223 | others. |
1357 | others. |
1224 | |
1358 | |
1225 | =head3 Summary |
1359 | =head3 Summary |
… | |
… | |
1233 | |
1367 | |
1234 | |
1368 | |
1235 | =head1 FORK |
1369 | =head1 FORK |
1236 | |
1370 | |
1237 | Most event libraries are not fork-safe. The ones who are usually are |
1371 | Most event libraries are not fork-safe. The ones who are usually are |
1238 | because they are so inefficient. Only L<EV> is fully fork-aware. |
1372 | because they rely on inefficient but fork-safe C<select> or C<poll> |
|
|
1373 | calls. Only L<EV> is fully fork-aware. |
1239 | |
1374 | |
1240 | If you have to fork, you must either do so I<before> creating your first |
1375 | If you have to fork, you must either do so I<before> creating your first |
1241 | watcher OR you must not use AnyEvent at all in the child. |
1376 | watcher OR you must not use AnyEvent at all in the child. |
1242 | |
1377 | |
1243 | |
1378 | |
… | |
… | |
1255 | |
1390 | |
1256 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1391 | BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} } |
1257 | |
1392 | |
1258 | use AnyEvent; |
1393 | use AnyEvent; |
1259 | |
1394 | |
|
|
1395 | Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can |
|
|
1396 | be used to probe what backend is used and gain other information (which is |
|
|
1397 | probably even less useful to an attacker than PERL_ANYEVENT_MODEL). |
|
|
1398 | |
1260 | |
1399 | |
1261 | =head1 SEE ALSO |
1400 | =head1 SEE ALSO |
1262 | |
1401 | |
1263 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1402 | Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>, |
1264 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |
1403 | L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>, |