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1NAME 1NAME
2 AnyEvent - provide framework for multiple event loops 2 AnyEvent - the DBI of event loop programming
3 3
4 EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported 4 EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async,
5 event loops. 5 Qt and POE are various supported event loops/environments.
6 6
7SYNOPSIS 7SYNOPSIS
8 use AnyEvent; 8 use AnyEvent;
9 9
10 # file descriptor readable 10 # file descriptor readable
… …
37 37
38INTRODUCTION/TUTORIAL 38INTRODUCTION/TUTORIAL
39 This manpage is mainly a reference manual. If you are interested in a 39 This manpage is mainly a reference manual. If you are interested in a
40 tutorial or some gentle introduction, have a look at the AnyEvent::Intro 40 tutorial or some gentle introduction, have a look at the AnyEvent::Intro
41 manpage. 41 manpage.
42
43SUPPORT
44 There is a mailinglist for discussing all things AnyEvent, and an IRC
45 channel, too.
46
47 See the AnyEvent project page at the Schmorpforge Ta-Sa Software
48 Repository, at <http://anyevent.schmorp.de>, for more info.
42 49
43WHY YOU SHOULD USE THIS MODULE (OR NOT) 50WHY YOU SHOULD USE THIS MODULE (OR NOT)
44 Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 51 Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
45 nowadays. So what is different about AnyEvent? 52 nowadays. So what is different about AnyEvent?
46 53
… …
166 Note that "my $w; $w =" combination. This is necessary because in Perl, 173 Note that "my $w; $w =" combination. This is necessary because in Perl,
167 my variables are only visible after the statement in which they are 174 my variables are only visible after the statement in which they are
168 declared. 175 declared.
169 176
170 I/O WATCHERS 177 I/O WATCHERS
178 $w = AnyEvent->io (
179 fh => <filehandle_or_fileno>,
180 poll => <"r" or "w">,
181 cb => <callback>,
182 );
183
171 You can create an I/O watcher by calling the "AnyEvent->io" method with 184 You can create an I/O watcher by calling the "AnyEvent->io" method with
172 the following mandatory key-value pairs as arguments: 185 the following mandatory key-value pairs as arguments:
173 186
174 "fh" is the Perl *file handle* (or a naked file descriptor) to watch for 187 "fh" is the Perl *file handle* (or a naked file descriptor) to watch for
175 events (AnyEvent might or might not keep a reference to this file 188 events (AnyEvent might or might not keep a reference to this file
… …
203 warn "read: $input\n"; 216 warn "read: $input\n";
204 undef $w; 217 undef $w;
205 }); 218 });
206 219
207 TIME WATCHERS 220 TIME WATCHERS
221 $w = AnyEvent->timer (after => <seconds>, cb => <callback>);
222
223 $w = AnyEvent->timer (
224 after => <fractional_seconds>,
225 interval => <fractional_seconds>,
226 cb => <callback>,
227 );
228
208 You can create a time watcher by calling the "AnyEvent->timer" method 229 You can create a time watcher by calling the "AnyEvent->timer" method
209 with the following mandatory arguments: 230 with the following mandatory arguments:
210 231
211 "after" specifies after how many seconds (fractional values are 232 "after" specifies after how many seconds (fractional values are
212 supported) the callback should be invoked. "cb" is the callback to 233 supported) the callback should be invoked. "cb" is the callback to
… …
333 time, which might affect timers and time-outs. 354 time, which might affect timers and time-outs.
334 355
335 When this is the case, you can call this method, which will update 356 When this is the case, you can call this method, which will update
336 the event loop's idea of "current time". 357 the event loop's idea of "current time".
337 358
359 A typical example would be a script in a web server (e.g.
360 "mod_perl") - when mod_perl executes the script, then the event loop
361 will have the wrong idea about the "current time" (being potentially
362 far in the past, when the script ran the last time). In that case
363 you should arrange a call to "AnyEvent->now_update" each time the
364 web server process wakes up again (e.g. at the start of your script,
365 or in a handler).
366
338 Note that updating the time *might* cause some events to be handled. 367 Note that updating the time *might* cause some events to be handled.
339 368
340 SIGNAL WATCHERS 369 SIGNAL WATCHERS
370 $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
371
341 You can watch for signals using a signal watcher, "signal" is the signal 372 You can watch for signals using a signal watcher, "signal" is the signal
342 *name* in uppercase and without any "SIG" prefix, "cb" is the Perl 373 *name* in uppercase and without any "SIG" prefix, "cb" is the Perl
343 callback to be invoked whenever a signal occurs. 374 callback to be invoked whenever a signal occurs.
344 375
345 Although the callback might get passed parameters, their value and 376 Although the callback might get passed parameters, their value and
… …
357 388
358 This watcher might use %SIG (depending on the event loop used), so 389 This watcher might use %SIG (depending on the event loop used), so
359 programs overwriting those signals directly will likely not work 390 programs overwriting those signals directly will likely not work
360 correctly. 391 correctly.
361 392
393 Example: exit on SIGINT
394
395 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
396
397 Signal Races, Delays and Workarounds
362 Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not 398 Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
363 support attaching callbacks to signals, which is a pity, as you cannot 399 callbacks to signals in a generic way, which is a pity, as you cannot do
364 do race-free signal handling in perl. AnyEvent will try to do it's best, 400 race-free signal handling in perl, requiring C libraries for this.
365 but in some cases, signals will be delayed. The maximum time a signal 401 AnyEvent will try to do it's best, which means in some cases, signals
366 might be delayed is specified in $AnyEvent::MAX_SIGNAL_LATENCY (default: 402 will be delayed. The maximum time a signal might be delayed is specified
367 10 seconds). This variable can be changed only before the first signal 403 in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable
368 watcher is created, and should be left alone otherwise. Higher values 404 can be changed only before the first signal watcher is created, and
405 should be left alone otherwise. This variable determines how often
406 AnyEvent polls for signals (in case a wake-up was missed). Higher values
369 will cause fewer spurious wake-ups, which is better for power and CPU 407 will cause fewer spurious wake-ups, which is better for power and CPU
408 saving.
409
370 saving. All these problems can be avoided by installing the optional 410 All these problems can be avoided by installing the optional
371 Async::Interrupt module. 411 Async::Interrupt module, which works with most event loops. It will not
372 412 work with inherently broken event loops such as Event or Event::Lib (and
373 Example: exit on SIGINT 413 not with POE currently, as POE does it's own workaround with one-second
374 414 latency). For those, you just have to suffer the delays.
375 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
376 415
377 CHILD PROCESS WATCHERS 416 CHILD PROCESS WATCHERS
417 $w = AnyEvent->child (pid => <process id>, cb => <callback>);
418
378 You can also watch on a child process exit and catch its exit status. 419 You can also watch on a child process exit and catch its exit status.
379 420
380 The child process is specified by the "pid" argument (if set to 0, it 421 The child process is specified by the "pid" argument (one some backends,
381 watches for any child process exit). The watcher will triggered only 422 using 0 watches for any child process exit, on others this will croak).
382 when the child process has finished and an exit status is available, not 423 The watcher will be triggered only when the child process has finished
383 on any trace events (stopped/continued). 424 and an exit status is available, not on any trace events
425 (stopped/continued).
384 426
385 The callback will be called with the pid and exit status (as returned by 427 The callback will be called with the pid and exit status (as returned by
386 waitpid), so unlike other watcher types, you *can* rely on child watcher 428 waitpid), so unlike other watcher types, you *can* rely on child watcher
387 callback arguments. 429 callback arguments.
388 430
… …
427 469
428 # do something else, then wait for process exit 470 # do something else, then wait for process exit
429 $done->recv; 471 $done->recv;
430 472
431 IDLE WATCHERS 473 IDLE WATCHERS
474 $w = AnyEvent->idle (cb => <callback>);
475
432 Sometimes there is a need to do something, but it is not so important to 476 Sometimes there is a need to do something, but it is not so important to
433 do it instantly, but only when there is nothing better to do. This 477 do it instantly, but only when there is nothing better to do. This
434 "nothing better to do" is usually defined to be "no other events need 478 "nothing better to do" is usually defined to be "no other events need
435 attention by the event loop". 479 attention by the event loop".
436 480
… …
461 } 505 }
462 }); 506 });
463 }); 507 });
464 508
465 CONDITION VARIABLES 509 CONDITION VARIABLES
510 $cv = AnyEvent->condvar;
511
512 $cv->send (<list>);
513 my @res = $cv->recv;
514
466 If you are familiar with some event loops you will know that all of them 515 If you are familiar with some event loops you will know that all of them
467 require you to run some blocking "loop", "run" or similar function that 516 require you to run some blocking "loop", "run" or similar function that
468 will actively watch for new events and call your callbacks. 517 will actively watch for new events and call your callbacks.
469 518
470 AnyEvent is slightly different: it expects somebody else to run the 519 AnyEvent is slightly different: it expects somebody else to run the
… …
490 Condition variables are similar to callbacks, except that you can 539 Condition variables are similar to callbacks, except that you can
491 optionally wait for them. They can also be called merge points - points 540 optionally wait for them. They can also be called merge points - points
492 in time where multiple outstanding events have been processed. And yet 541 in time where multiple outstanding events have been processed. And yet
493 another way to call them is transactions - each condition variable can 542 another way to call them is transactions - each condition variable can
494 be used to represent a transaction, which finishes at some point and 543 be used to represent a transaction, which finishes at some point and
495 delivers a result. 544 delivers a result. And yet some people know them as "futures" - a
545 promise to compute/deliver something that you can wait for.
496 546
497 Condition variables are very useful to signal that something has 547 Condition variables are very useful to signal that something has
498 finished, for example, if you write a module that does asynchronous http 548 finished, for example, if you write a module that does asynchronous http
499 requests, then a condition variable would be the ideal candidate to 549 requests, then a condition variable would be the ideal candidate to
500 signal the availability of results. The user can either act when the 550 signal the availability of results. The user can either act when the
… …
534 after => 1, 584 after => 1,
535 cb => sub { $result_ready->send }, 585 cb => sub { $result_ready->send },
536 ); 586 );
537 587
538 # this "blocks" (while handling events) till the callback 588 # this "blocks" (while handling events) till the callback
539 # calls -<send 589 # calls ->send
540 $result_ready->recv; 590 $result_ready->recv;
541 591
542 Example: wait for a timer, but take advantage of the fact that condition 592 Example: wait for a timer, but take advantage of the fact that condition
543 variables are also callable directly. 593 variables are also callable directly.
544 594
… …
601 into one. For example, a function that pings many hosts in parallel 651 into one. For example, a function that pings many hosts in parallel
602 might want to use a condition variable for the whole process. 652 might want to use a condition variable for the whole process.
603 653
604 Every call to "->begin" will increment a counter, and every call to 654 Every call to "->begin" will increment a counter, and every call to
605 "->end" will decrement it. If the counter reaches 0 in "->end", the 655 "->end" will decrement it. If the counter reaches 0 in "->end", the
606 (last) callback passed to "begin" will be executed. That callback is 656 (last) callback passed to "begin" will be executed, passing the
607 *supposed* to call "->send", but that is not required. If no 657 condvar as first argument. That callback is *supposed* to call
658 "->send", but that is not required. If no group callback was set,
608 callback was set, "send" will be called without any arguments. 659 "send" will be called without any arguments.
609 660
610 You can think of "$cv->send" giving you an OR condition (one call 661 You can think of "$cv->send" giving you an OR condition (one call
611 sends), while "$cv->begin" and "$cv->end" giving you an AND 662 sends), while "$cv->begin" and "$cv->end" giving you an AND
612 condition (all "begin" calls must be "end"'ed before the condvar 663 condition (all "begin" calls must be "end"'ed before the condvar
613 sends). 664 sends).
… …
641 that are begung can potentially be zero: 692 that are begung can potentially be zero:
642 693
643 my $cv = AnyEvent->condvar; 694 my $cv = AnyEvent->condvar;
644 695
645 my %result; 696 my %result;
646 $cv->begin (sub { $cv->send (\%result) }); 697 $cv->begin (sub { shift->send (\%result) });
647 698
648 for my $host (@list_of_hosts) { 699 for my $host (@list_of_hosts) {
649 $cv->begin; 700 $cv->begin;
650 ping_host_then_call_callback $host, sub { 701 ping_host_then_call_callback $host, sub {
651 $result{$host} = ...; 702 $result{$host} = ...;
… …
718 769
719 $cb = $cv->cb ($cb->($cv)) 770 $cb = $cv->cb ($cb->($cv))
720 This is a mutator function that returns the callback set and 771 This is a mutator function that returns the callback set and
721 optionally replaces it before doing so. 772 optionally replaces it before doing so.
722 773
723 The callback will be called when the condition becomes "true", i.e. 774 The callback will be called when the condition becomes (or already
724 when "send" or "croak" are called, with the only argument being the 775 was) "true", i.e. when "send" or "croak" are called (or were
725 condition variable itself. Calling "recv" inside the callback or at 776 called), with the only argument being the condition variable itself.
777 Calling "recv" inside the callback or at any later time is
726 any later time is guaranteed not to block. 778 guaranteed not to block.
727 779
728SUPPORTED EVENT LOOPS/BACKENDS 780SUPPORTED EVENT LOOPS/BACKENDS
729 The available backend classes are (every class has its own manpage): 781 The available backend classes are (every class has its own manpage):
730 782
731 Backends that are autoprobed when no other event loop can be found. 783 Backends that are autoprobed when no other event loop can be found.
732 EV is the preferred backend when no other event loop seems to be in 784 EV is the preferred backend when no other event loop seems to be in
733 use. If EV is not installed, then AnyEvent will try Event, and, 785 use. If EV is not installed, then AnyEvent will fall back to its own
734 failing that, will fall back to its own pure-perl implementation, 786 pure-perl implementation, which is available everywhere as it comes
735 which is available everywhere as it comes with AnyEvent itself. 787 with AnyEvent itself.
736 788
737 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 789 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
738 AnyEvent::Impl::Event based on Event, very stable, few glitches.
739 AnyEvent::Impl::Perl pure-perl implementation, fast and portable. 790 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
740 791
741 Backends that are transparently being picked up when they are used. 792 Backends that are transparently being picked up when they are used.
742 These will be used when they are currently loaded when the first 793 These will be used when they are currently loaded when the first
743 watcher is created, in which case it is assumed that the application 794 watcher is created, in which case it is assumed that the application
744 is using them. This means that AnyEvent will automatically pick the 795 is using them. This means that AnyEvent will automatically pick the
745 right backend when the main program loads an event module before 796 right backend when the main program loads an event module before
746 anything starts to create watchers. Nothing special needs to be done 797 anything starts to create watchers. Nothing special needs to be done
747 by the main program. 798 by the main program.
748 799
800 AnyEvent::Impl::Event based on Event, very stable, few glitches.
749 AnyEvent::Impl::Glib based on Glib, slow but very stable. 801 AnyEvent::Impl::Glib based on Glib, slow but very stable.
750 AnyEvent::Impl::Tk based on Tk, very broken. 802 AnyEvent::Impl::Tk based on Tk, very broken.
751 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 803 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
752 AnyEvent::Impl::POE based on POE, very slow, some limitations. 804 AnyEvent::Impl::POE based on POE, very slow, some limitations.
805 AnyEvent::Impl::Irssi used when running within irssi.
753 806
754 Backends with special needs. 807 Backends with special needs.
755 Qt requires the Qt::Application to be instantiated first, but will 808 Qt requires the Qt::Application to be instantiated first, but will
756 otherwise be picked up automatically. As long as the main program 809 otherwise be picked up automatically. As long as the main program
757 instantiates the application before any AnyEvent watchers are 810 instantiates the application before any AnyEvent watchers are
… …
822 creates and installs the global IO::AIO watcher in a "post_detect" 875 creates and installs the global IO::AIO watcher in a "post_detect"
823 block to avoid autodetecting the event module at load time. 876 block to avoid autodetecting the event module at load time.
824 877
825 If called in scalar or list context, then it creates and returns an 878 If called in scalar or list context, then it creates and returns an
826 object that automatically removes the callback again when it is 879 object that automatically removes the callback again when it is
880 destroyed (or "undef" when the hook was immediately executed). See
827 destroyed. See Coro::BDB for a case where this is useful. 881 AnyEvent::AIO for a case where this is useful.
882
883 Example: Create a watcher for the IO::AIO module and store it in
884 $WATCHER. Only do so after the event loop is initialised, though.
885
886 our WATCHER;
887
888 my $guard = AnyEvent::post_detect {
889 $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
890 };
891
892 # the ||= is important in case post_detect immediately runs the block,
893 # as to not clobber the newly-created watcher. assigning both watcher and
894 # post_detect guard to the same variable has the advantage of users being
895 # able to just C<undef $WATCHER> if the watcher causes them grief.
896
897 $WATCHER ||= $guard;
828 898
829 @AnyEvent::post_detect 899 @AnyEvent::post_detect
830 If there are any code references in this array (you can "push" to it 900 If there are any code references in this array (you can "push" to it
831 before or after loading AnyEvent), then they will called directly 901 before or after loading AnyEvent), then they will called directly
832 after the event loop has been chosen. 902 after the event loop has been chosen.
… …
971 Event::ExecFlow 1041 Event::ExecFlow
972 High level API for event-based execution flow control. 1042 High level API for event-based execution flow control.
973 1043
974 Coro 1044 Coro
975 Has special support for AnyEvent via Coro::AnyEvent. 1045 Has special support for AnyEvent via Coro::AnyEvent.
1046
1047SIMPLIFIED AE API
1048 Starting with version 5.0, AnyEvent officially supports a second, much
1049 simpler, API that is designed to reduce the calling, typing and memory
1050 overhead.
1051
1052 See the AE manpage for details.
976 1053
977ERROR AND EXCEPTION HANDLING 1054ERROR AND EXCEPTION HANDLING
978 In general, AnyEvent does not do any error handling - it relies on the 1055 In general, AnyEvent does not do any error handling - it relies on the
979 caller to do that if required. The AnyEvent::Strict module (see also the 1056 caller to do that if required. The AnyEvent::Strict module (see also the
980 "PERL_ANYEVENT_STRICT" environment variable, below) provides strict 1057 "PERL_ANYEVENT_STRICT" environment variable, below) provides strict
… …
1159 warn "read: $input\n"; # output what has been read 1236 warn "read: $input\n"; # output what has been read
1160 $cv->send if $input =~ /^q/i; # quit program if /^q/i 1237 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1161 }, 1238 },
1162 ); 1239 );
1163 1240
1164 my $time_watcher; # can only be used once
1165
1166 sub new_timer {
1167 $timer = AnyEvent->timer (after => 1, cb => sub { 1241 my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1168 warn "timeout\n"; # print 'timeout' about every second 1242 warn "timeout\n"; # print 'timeout' at most every second
1169 &new_timer; # and restart the time
1170 });
1171 } 1243 });
1172
1173 new_timer; # create first timer
1174 1244
1175 $cv->recv; # wait until user enters /^q/i 1245 $cv->recv; # wait until user enters /^q/i
1176 1246
1177REAL-WORLD EXAMPLE 1247REAL-WORLD EXAMPLE
1178 Consider the Net::FCP module. It features (among others) the following 1248 Consider the Net::FCP module. It features (among others) the following
… …
1305 through AnyEvent. The benchmark creates a lot of timers (with a zero 1375 through AnyEvent. The benchmark creates a lot of timers (with a zero
1306 timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1376 timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1307 which it is), lets them fire exactly once and destroys them again. 1377 which it is), lets them fire exactly once and destroys them again.
1308 1378
1309 Source code for this benchmark is found as eg/bench in the AnyEvent 1379 Source code for this benchmark is found as eg/bench in the AnyEvent
1310 distribution. 1380 distribution. It uses the AE interface, which makes a real difference
1381 for the EV and Perl backends only.
1311 1382
1312 Explanation of the columns 1383 Explanation of the columns
1313 *watcher* is the number of event watchers created/destroyed. Since 1384 *watcher* is the number of event watchers created/destroyed. Since
1314 different event models feature vastly different performances, each event 1385 different event models feature vastly different performances, each event
1315 loop was given a number of watchers so that overall runtime is 1386 loop was given a number of watchers so that overall runtime is
… …
1334 *destroy* is the time, in microseconds, that it takes to destroy a 1405 *destroy* is the time, in microseconds, that it takes to destroy a
1335 single watcher. 1406 single watcher.
1336 1407
1337 Results 1408 Results
1338 name watchers bytes create invoke destroy comment 1409 name watchers bytes create invoke destroy comment
1339 EV/EV 400000 224 0.47 0.35 0.27 EV native interface 1410 EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1340 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers 1411 EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1341 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal 1412 Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1342 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation 1413 Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1343 Event/Event 16000 517 32.20 31.80 0.81 Event native interface 1414 Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1344 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers 1415 Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1345 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll 1416 IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1346 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll 1417 IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1347 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour 1418 Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1348 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers 1419 Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1349 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event 1420 POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1350 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select 1421 POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1351 1422
1352 Discussion 1423 Discussion
1353 The benchmark does *not* measure scalability of the event loop very 1424 The benchmark does *not* measure scalability of the event loop very
1354 well. For example, a select-based event loop (such as the pure perl one) 1425 well. For example, a select-based event loop (such as the pure perl one)
1355 can never compete with an event loop that uses epoll when the number of 1426 can never compete with an event loop that uses epoll when the number of
… …
1366 benchmark machine, handling an event takes roughly 1600 CPU cycles with 1437 benchmark machine, handling an event takes roughly 1600 CPU cycles with
1367 EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 1438 EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000
1368 CPU cycles with POE. 1439 CPU cycles with POE.
1369 1440
1370 "EV" is the sole leader regarding speed and memory use, which are both 1441 "EV" is the sole leader regarding speed and memory use, which are both
1371 maximal/minimal, respectively. Even when going through AnyEvent, it uses 1442 maximal/minimal, respectively. When using the AE API there is zero
1443 overhead (when going through the AnyEvent API create is about 5-6 times
1444 slower, with other times being equal, so still uses far less memory than
1372 far less memory than any other event loop and is still faster than Event 1445 any other event loop and is still faster than Event natively).
1373 natively.
1374 1446
1375 The pure perl implementation is hit in a few sweet spots (both the 1447 The pure perl implementation is hit in a few sweet spots (both the
1376 constant timeout and the use of a single fd hit optimisations in the 1448 constant timeout and the use of a single fd hit optimisations in the
1377 perl interpreter and the backend itself). Nevertheless this shows that 1449 perl interpreter and the backend itself). Nevertheless this shows that
1378 it adds very little overhead in itself. Like any select-based backend 1450 it adds very little overhead in itself. Like any select-based backend
… …
1448 In this benchmark, we use 10000 socket pairs (20000 sockets), of which 1520 In this benchmark, we use 10000 socket pairs (20000 sockets), of which
1449 100 (1%) are active. This mirrors the activity of large servers with 1521 100 (1%) are active. This mirrors the activity of large servers with
1450 many connections, most of which are idle at any one point in time. 1522 many connections, most of which are idle at any one point in time.
1451 1523
1452 Source code for this benchmark is found as eg/bench2 in the AnyEvent 1524 Source code for this benchmark is found as eg/bench2 in the AnyEvent
1453 distribution. 1525 distribution. It uses the AE interface, which makes a real difference
1526 for the EV and Perl backends only.
1454 1527
1455 Explanation of the columns 1528 Explanation of the columns
1456 *sockets* is the number of sockets, and twice the number of "servers" 1529 *sockets* is the number of sockets, and twice the number of "servers"
1457 (as each server has a read and write socket end). 1530 (as each server has a read and write socket end).
1458 1531
… …
1464 forwarding it to another server. This includes deleting the old timeout 1537 forwarding it to another server. This includes deleting the old timeout
1465 and creating a new one that moves the timeout into the future. 1538 and creating a new one that moves the timeout into the future.
1466 1539
1467 Results 1540 Results
1468 name sockets create request 1541 name sockets create request
1469 EV 20000 69.01 11.16 1542 EV 20000 62.66 7.99
1470 Perl 20000 73.32 35.87 1543 Perl 20000 68.32 32.64
1471 IOAsync 20000 157.00 98.14 epoll 1544 IOAsync 20000 174.06 101.15 epoll
1472 IOAsync 20000 159.31 616.06 poll 1545 IOAsync 20000 174.67 610.84 poll
1473 Event 20000 212.62 257.32 1546 Event 20000 202.69 242.91
1474 Glib 20000 651.16 1896.30 1547 Glib 20000 557.01 1689.52
1475 POE 20000 349.67 12317.24 uses POE::Loop::Event 1548 POE 20000 341.54 12086.32 uses POE::Loop::Event
1476 1549
1477 Discussion 1550 Discussion
1478 This benchmark *does* measure scalability and overall performance of the 1551 This benchmark *does* measure scalability and overall performance of the
1479 particular event loop. 1552 particular event loop.
1480 1553
… …
1593 As you can see, the AnyEvent + EV combination even beats the 1666 As you can see, the AnyEvent + EV combination even beats the
1594 hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl 1667 hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1595 backend easily beats IO::Lambda and POE. 1668 backend easily beats IO::Lambda and POE.
1596 1669
1597 And even the 100% non-blocking version written using the high-level (and 1670 And even the 100% non-blocking version written using the high-level (and
1598 slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a 1671 slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda
1599 large margin, even though it does all of DNS, tcp-connect and socket I/O 1672 higher level ("unoptimised") abstractions by a large margin, even though
1600 in a non-blocking way. 1673 it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
1601 1674
1602 The two AnyEvent benchmarks programs can be found as eg/ae0.pl and 1675 The two AnyEvent benchmarks programs can be found as eg/ae0.pl and
1603 eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are 1676 eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
1604 part of the IO::lambda distribution and were used without any changes. 1677 part of the IO::Lambda distribution and were used without any changes.
1605 1678
1606SIGNALS 1679SIGNALS
1607 AnyEvent currently installs handlers for these signals: 1680 AnyEvent currently installs handlers for these signals:
1608 1681
1609 SIGCHLD 1682 SIGCHLD
… …
1644 Async::Interrupt 1717 Async::Interrupt
1645 This slightly arcane module is used to implement fast signal 1718 This slightly arcane module is used to implement fast signal
1646 handling: To my knowledge, there is no way to do completely 1719 handling: To my knowledge, there is no way to do completely
1647 race-free and quick signal handling in pure perl. To ensure that 1720 race-free and quick signal handling in pure perl. To ensure that
1648 signals still get delivered, AnyEvent will start an interval timer 1721 signals still get delivered, AnyEvent will start an interval timer
1649 to wake up perl (and catch the signals) with soemd elay (default is 1722 to wake up perl (and catch the signals) with some delay (default is
1650 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). 1723 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).
1651 1724
1652 If this module is available, then it will be used to implement 1725 If this module is available, then it will be used to implement
1653 signal catching, which means that signals will not be delayed, and 1726 signal catching, which means that signals will not be delayed, and
1654 the event loop will not be interrupted regularly, which is more 1727 the event loop will not be interrupted regularly, which is more
1655 efficient (And good for battery life on laptops). 1728 efficient (And good for battery life on laptops).
1656 1729
1657 This affects not just the pure-perl event loop, but also other event 1730 This affects not just the pure-perl event loop, but also other event
1658 loops that have no signal handling on their own (e.g. Glib, Tk, Qt). 1731 loops that have no signal handling on their own (e.g. Glib, Tk, Qt).
1732
1733 Some event loops (POE, Event, Event::Lib) offer signal watchers
1734 natively, and either employ their own workarounds (POE) or use
1735 AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY).
1736 Installing Async::Interrupt does nothing for those backends.
1659 1737
1660 EV This module isn't really "optional", as it is simply one of the 1738 EV This module isn't really "optional", as it is simply one of the
1661 backend event loops that AnyEvent can use. However, it is simply the 1739 backend event loops that AnyEvent can use. However, it is simply the
1662 best event loop available in terms of features, speed and stability: 1740 best event loop available in terms of features, speed and stability:
1663 It supports the AnyEvent API optimally, implements all the watcher 1741 It supports the AnyEvent API optimally, implements all the watcher
… …
1672 "AnyEvent::Util::guard". This speeds up guards considerably (and 1750 "AnyEvent::Util::guard". This speeds up guards considerably (and
1673 uses a lot less memory), but otherwise doesn't affect guard 1751 uses a lot less memory), but otherwise doesn't affect guard
1674 operation much. It is purely used for performance. 1752 operation much. It is purely used for performance.
1675 1753
1676 JSON and JSON::XS 1754 JSON and JSON::XS
1677 This module is required when you want to read or write JSON data via 1755 One of these modules is required when you want to read or write JSON
1678 AnyEvent::Handle. It is also written in pure-perl, but can take 1756 data via AnyEvent::Handle. It is also written in pure-perl, but can
1679 advantage of the ulta-high-speed JSON::XS module when it is 1757 take advantage of the ultra-high-speed JSON::XS module when it is
1680 installed. 1758 installed.
1681 1759
1682 In fact, AnyEvent::Handle will use JSON::XS by default if it is 1760 In fact, AnyEvent::Handle will use JSON::XS by default if it is
1683 installed. 1761 installed.
1684 1762
… …
1741 Event::Lib, Qt, POE. 1819 Event::Lib, Qt, POE.
1742 1820
1743 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, 1821 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1744 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, 1822 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1745 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, 1823 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
1746 AnyEvent::Impl::IOAsync. 1824 AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.
1747 1825
1748 Non-blocking file handles, sockets, TCP clients and servers: 1826 Non-blocking file handles, sockets, TCP clients and servers:
1749 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. 1827 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1750 1828
1751 Asynchronous DNS: AnyEvent::DNS. 1829 Asynchronous DNS: AnyEvent::DNS.

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