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Revision 1.46 by root, Sat Jul 18 05:19:09 2009 UTC vs.
Revision 1.54 by root, Tue Sep 1 18:27:46 2009 UTC

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
… …
336 the event loop's idea of "current time". 357 the event loop's idea of "current time".
337 358
338 Note that updating the time *might* cause some events to be handled. 359 Note that updating the time *might* cause some events to be handled.
339 360
340 SIGNAL WATCHERS 361 SIGNAL WATCHERS
362 $w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
363
341 You can watch for signals using a signal watcher, "signal" is the signal 364 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 365 *name* in uppercase and without any "SIG" prefix, "cb" is the Perl
343 callback to be invoked whenever a signal occurs. 366 callback to be invoked whenever a signal occurs.
344 367
345 Although the callback might get passed parameters, their value and 368 Although the callback might get passed parameters, their value and
… …
357 380
358 This watcher might use %SIG (depending on the event loop used), so 381 This watcher might use %SIG (depending on the event loop used), so
359 programs overwriting those signals directly will likely not work 382 programs overwriting those signals directly will likely not work
360 correctly. 383 correctly.
361 384
385 Example: exit on SIGINT
386
387 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
388
389 Signal Races, Delays and Workarounds
362 Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not 390 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 391 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, 392 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 393 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: 394 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 395 in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable
368 watcher is created, and should be left alone otherwise. Higher values 396 can be changed only before the first signal watcher is created, and
397 should be left alone otherwise. This variable determines how often
398 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 399 will cause fewer spurious wake-ups, which is better for power and CPU
400 saving.
401
370 saving. All these problems can be avoided by installing the optional 402 All these problems can be avoided by installing the optional
371 Async::Interrupt module. 403 Async::Interrupt module, which works with most event loops. It will not
372 404 work with inherently broken event loops such as Event or Event::Lib (and
373 Example: exit on SIGINT 405 not with POE currently, as POE does it's own workaround with one-second
374 406 latency). For those, you just have to suffer the delays.
375 my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
376 407
377 CHILD PROCESS WATCHERS 408 CHILD PROCESS WATCHERS
409 $w = AnyEvent->child (pid => <process id>, cb => <callback>);
410
378 You can also watch on a child process exit and catch its exit status. 411 You can also watch on a child process exit and catch its exit status.
379 412
380 The child process is specified by the "pid" argument (if set to 0, it 413 The child process is specified by the "pid" argument (one some backends,
381 watches for any child process exit). The watcher will triggered only 414 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 415 The watcher will be triggered only when the child process has finished
383 on any trace events (stopped/continued). 416 and an exit status is available, not on any trace events
417 (stopped/continued).
384 418
385 The callback will be called with the pid and exit status (as returned by 419 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 420 waitpid), so unlike other watcher types, you *can* rely on child watcher
387 callback arguments. 421 callback arguments.
388 422
… …
427 461
428 # do something else, then wait for process exit 462 # do something else, then wait for process exit
429 $done->recv; 463 $done->recv;
430 464
431 IDLE WATCHERS 465 IDLE WATCHERS
466 $w = AnyEvent->idle (cb => <callback>);
467
432 Sometimes there is a need to do something, but it is not so important to 468 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 469 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 470 "nothing better to do" is usually defined to be "no other events need
435 attention by the event loop". 471 attention by the event loop".
436 472
… …
461 } 497 }
462 }); 498 });
463 }); 499 });
464 500
465 CONDITION VARIABLES 501 CONDITION VARIABLES
502 $cv = AnyEvent->condvar;
503
504 $cv->send (<list>);
505 my @res = $cv->recv;
506
466 If you are familiar with some event loops you will know that all of them 507 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 508 require you to run some blocking "loop", "run" or similar function that
468 will actively watch for new events and call your callbacks. 509 will actively watch for new events and call your callbacks.
469 510
470 AnyEvent is slightly different: it expects somebody else to run the 511 AnyEvent is slightly different: it expects somebody else to run the
… …
490 Condition variables are similar to callbacks, except that you can 531 Condition variables are similar to callbacks, except that you can
491 optionally wait for them. They can also be called merge points - points 532 optionally wait for them. They can also be called merge points - points
492 in time where multiple outstanding events have been processed. And yet 533 in time where multiple outstanding events have been processed. And yet
493 another way to call them is transactions - each condition variable can 534 another way to call them is transactions - each condition variable can
494 be used to represent a transaction, which finishes at some point and 535 be used to represent a transaction, which finishes at some point and
495 delivers a result. 536 delivers a result. And yet some people know them as "futures" - a
537 promise to compute/deliver something that you can wait for.
496 538
497 Condition variables are very useful to signal that something has 539 Condition variables are very useful to signal that something has
498 finished, for example, if you write a module that does asynchronous http 540 finished, for example, if you write a module that does asynchronous http
499 requests, then a condition variable would be the ideal candidate to 541 requests, then a condition variable would be the ideal candidate to
500 signal the availability of results. The user can either act when the 542 signal the availability of results. The user can either act when the
… …
534 after => 1, 576 after => 1,
535 cb => sub { $result_ready->send }, 577 cb => sub { $result_ready->send },
536 ); 578 );
537 579
538 # this "blocks" (while handling events) till the callback 580 # this "blocks" (while handling events) till the callback
539 # calls -<send 581 # calls ->send
540 $result_ready->recv; 582 $result_ready->recv;
541 583
542 Example: wait for a timer, but take advantage of the fact that condition 584 Example: wait for a timer, but take advantage of the fact that condition
543 variables are also callable directly. 585 variables are also callable directly.
544 586
… …
601 into one. For example, a function that pings many hosts in parallel 643 into one. For example, a function that pings many hosts in parallel
602 might want to use a condition variable for the whole process. 644 might want to use a condition variable for the whole process.
603 645
604 Every call to "->begin" will increment a counter, and every call to 646 Every call to "->begin" will increment a counter, and every call to
605 "->end" will decrement it. If the counter reaches 0 in "->end", the 647 "->end" will decrement it. If the counter reaches 0 in "->end", the
606 (last) callback passed to "begin" will be executed. That callback is 648 (last) callback passed to "begin" will be executed, passing the
607 *supposed* to call "->send", but that is not required. If no 649 condvar as first argument. That callback is *supposed* to call
650 "->send", but that is not required. If no group callback was set,
608 callback was set, "send" will be called without any arguments. 651 "send" will be called without any arguments.
609 652
610 You can think of "$cv->send" giving you an OR condition (one call 653 You can think of "$cv->send" giving you an OR condition (one call
611 sends), while "$cv->begin" and "$cv->end" giving you an AND 654 sends), while "$cv->begin" and "$cv->end" giving you an AND
612 condition (all "begin" calls must be "end"'ed before the condvar 655 condition (all "begin" calls must be "end"'ed before the condvar
613 sends). 656 sends).
… …
641 that are begung can potentially be zero: 684 that are begung can potentially be zero:
642 685
643 my $cv = AnyEvent->condvar; 686 my $cv = AnyEvent->condvar;
644 687
645 my %result; 688 my %result;
646 $cv->begin (sub { $cv->send (\%result) }); 689 $cv->begin (sub { shift->send (\%result) });
647 690
648 for my $host (@list_of_hosts) { 691 for my $host (@list_of_hosts) {
649 $cv->begin; 692 $cv->begin;
650 ping_host_then_call_callback $host, sub { 693 ping_host_then_call_callback $host, sub {
651 $result{$host} = ...; 694 $result{$host} = ...;
… …
718 761
719 $cb = $cv->cb ($cb->($cv)) 762 $cb = $cv->cb ($cb->($cv))
720 This is a mutator function that returns the callback set and 763 This is a mutator function that returns the callback set and
721 optionally replaces it before doing so. 764 optionally replaces it before doing so.
722 765
723 The callback will be called when the condition becomes "true", i.e. 766 The callback will be called when the condition becomes (or already
724 when "send" or "croak" are called, with the only argument being the 767 was) "true", i.e. when "send" or "croak" are called (or were
725 condition variable itself. Calling "recv" inside the callback or at 768 called), with the only argument being the condition variable itself.
769 Calling "recv" inside the callback or at any later time is
726 any later time is guaranteed not to block. 770 guaranteed not to block.
727 771
728SUPPORTED EVENT LOOPS/BACKENDS 772SUPPORTED EVENT LOOPS/BACKENDS
729 The available backend classes are (every class has its own manpage): 773 The available backend classes are (every class has its own manpage):
730 774
731 Backends that are autoprobed when no other event loop can be found. 775 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 776 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, 777 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, 778 pure-perl implementation, which is available everywhere as it comes
735 which is available everywhere as it comes with AnyEvent itself. 779 with AnyEvent itself.
736 780
737 AnyEvent::Impl::EV based on EV (interface to libev, best choice). 781 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. 782 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
740 783
741 Backends that are transparently being picked up when they are used. 784 Backends that are transparently being picked up when they are used.
742 These will be used when they are currently loaded when the first 785 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 786 watcher is created, in which case it is assumed that the application
744 is using them. This means that AnyEvent will automatically pick the 787 is using them. This means that AnyEvent will automatically pick the
745 right backend when the main program loads an event module before 788 right backend when the main program loads an event module before
746 anything starts to create watchers. Nothing special needs to be done 789 anything starts to create watchers. Nothing special needs to be done
747 by the main program. 790 by the main program.
748 791
792 AnyEvent::Impl::Event based on Event, very stable, few glitches.
749 AnyEvent::Impl::Glib based on Glib, slow but very stable. 793 AnyEvent::Impl::Glib based on Glib, slow but very stable.
750 AnyEvent::Impl::Tk based on Tk, very broken. 794 AnyEvent::Impl::Tk based on Tk, very broken.
751 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. 795 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
752 AnyEvent::Impl::POE based on POE, very slow, some limitations. 796 AnyEvent::Impl::POE based on POE, very slow, some limitations.
797 AnyEvent::Impl::Irssi used when running within irssi.
753 798
754 Backends with special needs. 799 Backends with special needs.
755 Qt requires the Qt::Application to be instantiated first, but will 800 Qt requires the Qt::Application to be instantiated first, but will
756 otherwise be picked up automatically. As long as the main program 801 otherwise be picked up automatically. As long as the main program
757 instantiates the application before any AnyEvent watchers are 802 instantiates the application before any AnyEvent watchers are
… …
822 creates and installs the global IO::AIO watcher in a "post_detect" 867 creates and installs the global IO::AIO watcher in a "post_detect"
823 block to avoid autodetecting the event module at load time. 868 block to avoid autodetecting the event module at load time.
824 869
825 If called in scalar or list context, then it creates and returns an 870 If called in scalar or list context, then it creates and returns an
826 object that automatically removes the callback again when it is 871 object that automatically removes the callback again when it is
872 destroyed (or "undef" when the hook was immediately executed). See
827 destroyed. See Coro::BDB for a case where this is useful. 873 AnyEvent::AIO for a case where this is useful.
874
875 Example: Create a watcher for the IO::AIO module and store it in
876 $WATCHER. Only do so after the event loop is initialised, though.
877
878 our WATCHER;
879
880 my $guard = AnyEvent::post_detect {
881 $WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
882 };
883
884 # the ||= is important in case post_detect immediately runs the block,
885 # as to not clobber the newly-created watcher. assigning both watcher and
886 # post_detect guard to the same variable has the advantage of users being
887 # able to just C<undef $WATCHER> if the watcher causes them grief.
888
889 $WATCHER ||= $guard;
828 890
829 @AnyEvent::post_detect 891 @AnyEvent::post_detect
830 If there are any code references in this array (you can "push" to it 892 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 893 before or after loading AnyEvent), then they will called directly
832 after the event loop has been chosen. 894 after the event loop has been chosen.
… …
971 Event::ExecFlow 1033 Event::ExecFlow
972 High level API for event-based execution flow control. 1034 High level API for event-based execution flow control.
973 1035
974 Coro 1036 Coro
975 Has special support for AnyEvent via Coro::AnyEvent. 1037 Has special support for AnyEvent via Coro::AnyEvent.
1038
1039SIMPLIFIED AE API
1040 Starting with version 5.0, AnyEvent officially supports a second, much
1041 simpler, API that is designed to reduce the calling, typing and memory
1042 overhead.
1043
1044 See the AE manpage for details.
976 1045
977ERROR AND EXCEPTION HANDLING 1046ERROR AND EXCEPTION HANDLING
978 In general, AnyEvent does not do any error handling - it relies on the 1047 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 1048 caller to do that if required. The AnyEvent::Strict module (see also the
980 "PERL_ANYEVENT_STRICT" environment variable, below) provides strict 1049 "PERL_ANYEVENT_STRICT" environment variable, below) provides strict
… …
1159 warn "read: $input\n"; # output what has been read 1228 warn "read: $input\n"; # output what has been read
1160 $cv->send if $input =~ /^q/i; # quit program if /^q/i 1229 $cv->send if $input =~ /^q/i; # quit program if /^q/i
1161 }, 1230 },
1162 ); 1231 );
1163 1232
1164 my $time_watcher; # can only be used once
1165
1166 sub new_timer {
1167 $timer = AnyEvent->timer (after => 1, cb => sub { 1233 my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1168 warn "timeout\n"; # print 'timeout' about every second 1234 warn "timeout\n"; # print 'timeout' at most every second
1169 &new_timer; # and restart the time
1170 });
1171 } 1235 });
1172
1173 new_timer; # create first timer
1174 1236
1175 $cv->recv; # wait until user enters /^q/i 1237 $cv->recv; # wait until user enters /^q/i
1176 1238
1177REAL-WORLD EXAMPLE 1239REAL-WORLD EXAMPLE
1178 Consider the Net::FCP module. It features (among others) the following 1240 Consider the Net::FCP module. It features (among others) the following
… …
1305 through AnyEvent. The benchmark creates a lot of timers (with a zero 1367 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, 1368 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. 1369 which it is), lets them fire exactly once and destroys them again.
1308 1370
1309 Source code for this benchmark is found as eg/bench in the AnyEvent 1371 Source code for this benchmark is found as eg/bench in the AnyEvent
1310 distribution. 1372 distribution. It uses the AE interface, which makes a real difference
1373 for the EV and Perl backends only.
1311 1374
1312 Explanation of the columns 1375 Explanation of the columns
1313 *watcher* is the number of event watchers created/destroyed. Since 1376 *watcher* is the number of event watchers created/destroyed. Since
1314 different event models feature vastly different performances, each event 1377 different event models feature vastly different performances, each event
1315 loop was given a number of watchers so that overall runtime is 1378 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 1397 *destroy* is the time, in microseconds, that it takes to destroy a
1335 single watcher. 1398 single watcher.
1336 1399
1337 Results 1400 Results
1338 name watchers bytes create invoke destroy comment 1401 name watchers bytes create invoke destroy comment
1339 EV/EV 400000 224 0.47 0.35 0.27 EV native interface 1402 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 1403 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 1404 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 1405 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 1406 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 1407 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 1408 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 1409 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 1410 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 1411 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 1412 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 1413 POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1351 1414
1352 Discussion 1415 Discussion
1353 The benchmark does *not* measure scalability of the event loop very 1416 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) 1417 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 1418 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 1429 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 1430 EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000
1368 CPU cycles with POE. 1431 CPU cycles with POE.
1369 1432
1370 "EV" is the sole leader regarding speed and memory use, which are both 1433 "EV" is the sole leader regarding speed and memory use, which are both
1371 maximal/minimal, respectively. Even when going through AnyEvent, it uses 1434 maximal/minimal, respectively. When using the AE API there is zero
1435 overhead (when going through the AnyEvent API create is about 5-6 times
1436 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 1437 any other event loop and is still faster than Event natively).
1373 natively.
1374 1438
1375 The pure perl implementation is hit in a few sweet spots (both the 1439 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 1440 constant timeout and the use of a single fd hit optimisations in the
1377 perl interpreter and the backend itself). Nevertheless this shows that 1441 perl interpreter and the backend itself). Nevertheless this shows that
1378 it adds very little overhead in itself. Like any select-based backend 1442 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 1512 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 1513 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. 1514 many connections, most of which are idle at any one point in time.
1451 1515
1452 Source code for this benchmark is found as eg/bench2 in the AnyEvent 1516 Source code for this benchmark is found as eg/bench2 in the AnyEvent
1453 distribution. 1517 distribution. It uses the AE interface, which makes a real difference
1518 for the EV and Perl backends only.
1454 1519
1455 Explanation of the columns 1520 Explanation of the columns
1456 *sockets* is the number of sockets, and twice the number of "servers" 1521 *sockets* is the number of sockets, and twice the number of "servers"
1457 (as each server has a read and write socket end). 1522 (as each server has a read and write socket end).
1458 1523
… …
1464 forwarding it to another server. This includes deleting the old timeout 1529 forwarding it to another server. This includes deleting the old timeout
1465 and creating a new one that moves the timeout into the future. 1530 and creating a new one that moves the timeout into the future.
1466 1531
1467 Results 1532 Results
1468 name sockets create request 1533 name sockets create request
1469 EV 20000 69.01 11.16 1534 EV 20000 62.66 7.99
1470 Perl 20000 73.32 35.87 1535 Perl 20000 68.32 32.64
1471 IOAsync 20000 157.00 98.14 epoll 1536 IOAsync 20000 174.06 101.15 epoll
1472 IOAsync 20000 159.31 616.06 poll 1537 IOAsync 20000 174.67 610.84 poll
1473 Event 20000 212.62 257.32 1538 Event 20000 202.69 242.91
1474 Glib 20000 651.16 1896.30 1539 Glib 20000 557.01 1689.52
1475 POE 20000 349.67 12317.24 uses POE::Loop::Event 1540 POE 20000 341.54 12086.32 uses POE::Loop::Event
1476 1541
1477 Discussion 1542 Discussion
1478 This benchmark *does* measure scalability and overall performance of the 1543 This benchmark *does* measure scalability and overall performance of the
1479 particular event loop. 1544 particular event loop.
1480 1545
… …
1593 As you can see, the AnyEvent + EV combination even beats the 1658 As you can see, the AnyEvent + EV combination even beats the
1594 hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl 1659 hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1595 backend easily beats IO::Lambda and POE. 1660 backend easily beats IO::Lambda and POE.
1596 1661
1597 And even the 100% non-blocking version written using the high-level (and 1662 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 1663 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 1664 higher level ("unoptimised") abstractions by a large margin, even though
1600 in a non-blocking way. 1665 it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
1601 1666
1602 The two AnyEvent benchmarks programs can be found as eg/ae0.pl and 1667 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 1668 eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
1604 part of the IO::lambda distribution and were used without any changes. 1669 part of the IO::Lambda distribution and were used without any changes.
1605 1670
1606SIGNALS 1671SIGNALS
1607 AnyEvent currently installs handlers for these signals: 1672 AnyEvent currently installs handlers for these signals:
1608 1673
1609 SIGCHLD 1674 SIGCHLD
… …
1644 Async::Interrupt 1709 Async::Interrupt
1645 This slightly arcane module is used to implement fast signal 1710 This slightly arcane module is used to implement fast signal
1646 handling: To my knowledge, there is no way to do completely 1711 handling: To my knowledge, there is no way to do completely
1647 race-free and quick signal handling in pure perl. To ensure that 1712 race-free and quick signal handling in pure perl. To ensure that
1648 signals still get delivered, AnyEvent will start an interval timer 1713 signals still get delivered, AnyEvent will start an interval timer
1649 to wake up perl (and catch the signals) with soemd elay (default is 1714 to wake up perl (and catch the signals) with some delay (default is
1650 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY). 1715 10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).
1651 1716
1652 If this module is available, then it will be used to implement 1717 If this module is available, then it will be used to implement
1653 signal catching, which means that signals will not be delayed, and 1718 signal catching, which means that signals will not be delayed, and
1654 the event loop will not be interrupted regularly, which is more 1719 the event loop will not be interrupted regularly, which is more
1655 efficient (And good for battery life on laptops). 1720 efficient (And good for battery life on laptops).
1656 1721
1657 This affects not just the pure-perl event loop, but also other event 1722 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). 1723 loops that have no signal handling on their own (e.g. Glib, Tk, Qt).
1724
1725 Some event loops (POE, Event, Event::Lib) offer signal watchers
1726 natively, and either employ their own workarounds (POE) or use
1727 AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY).
1728 Installing Async::Interrupt does nothing for those backends.
1659 1729
1660 EV This module isn't really "optional", as it is simply one of the 1730 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 1731 backend event loops that AnyEvent can use. However, it is simply the
1662 best event loop available in terms of features, speed and stability: 1732 best event loop available in terms of features, speed and stability:
1663 It supports the AnyEvent API optimally, implements all the watcher 1733 It supports the AnyEvent API optimally, implements all the watcher
… …
1674 operation much. It is purely used for performance. 1744 operation much. It is purely used for performance.
1675 1745
1676 JSON and JSON::XS 1746 JSON and JSON::XS
1677 This module is required when you want to read or write JSON data via 1747 This module is required when you want to read or write JSON data via
1678 AnyEvent::Handle. It is also written in pure-perl, but can take 1748 AnyEvent::Handle. It is also written in pure-perl, but can take
1679 advantage of the ulta-high-speed JSON::XS module when it is 1749 advantage of the ultra-high-speed JSON::XS module when it is
1680 installed. 1750 installed.
1681 1751
1682 In fact, AnyEvent::Handle will use JSON::XS by default if it is 1752 In fact, AnyEvent::Handle will use JSON::XS by default if it is
1683 installed. 1753 installed.
1684 1754
… …
1741 Event::Lib, Qt, POE. 1811 Event::Lib, Qt, POE.
1742 1812
1743 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, 1813 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1744 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, 1814 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1745 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE, 1815 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
1746 AnyEvent::Impl::IOAsync. 1816 AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.
1747 1817
1748 Non-blocking file handles, sockets, TCP clients and servers: 1818 Non-blocking file handles, sockets, TCP clients and servers:
1749 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS. 1819 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1750 1820
1751 Asynchronous DNS: AnyEvent::DNS. 1821 Asynchronous DNS: AnyEvent::DNS.

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