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Revision 1.40 by root, Tue Jun 23 23:37:32 2009 UTC vs.
Revision 1.43 by root, Thu Jul 9 08:37:06 2009 UTC

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169 169
170 I/O WATCHERS 170 I/O WATCHERS
171 You can create an I/O watcher by calling the "AnyEvent->io" method with 171 You can create an I/O watcher by calling the "AnyEvent->io" method with
172 the following mandatory key-value pairs as arguments: 172 the following mandatory key-value pairs as arguments:
173 173
174 "fh" is the Perl *file handle* (*not* file descriptor) to watch for 174 "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 175 events (AnyEvent might or might not keep a reference to this file
176 handle). Note that only file handles pointing to things for which 176 handle). Note that only file handles pointing to things for which
177 non-blocking operation makes sense are allowed. This includes sockets, 177 non-blocking operation makes sense are allowed. This includes sockets,
178 most character devices, pipes, fifos and so on, but not for example 178 most character devices, pipes, fifos and so on, but not for example
179 files or block devices. 179 files or block devices.
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380 380
381 There is a slight catch to child watchers, however: you usually start 381 There is a slight catch to child watchers, however: you usually start
382 them *after* the child process was created, and this means the process 382 them *after* the child process was created, and this means the process
383 could have exited already (and no SIGCHLD will be sent anymore). 383 could have exited already (and no SIGCHLD will be sent anymore).
384 384
385 Not all event models handle this correctly (POE doesn't), but even for 385 Not all event models handle this correctly (neither POE nor IO::Async
386 do, see their AnyEvent::Impl manpages for details), but even for event
386 event models that *do* handle this correctly, they usually need to be 387 models that *do* handle this correctly, they usually need to be loaded
387 loaded before the process exits (i.e. before you fork in the first 388 before the process exits (i.e. before you fork in the first place).
388 place). 389 AnyEvent's pure perl event loop handles all cases correctly regardless
390 of when you start the watcher.
389 391
390 This means you cannot create a child watcher as the very first thing in 392 This means you cannot create a child watcher as the very first thing in
391 an AnyEvent program, you *have* to create at least one watcher before 393 an AnyEvent program, you *have* to create at least one watcher before
392 you "fork" the child (alternatively, you can call "AnyEvent::detect"). 394 you "fork" the child (alternatively, you can call "AnyEvent::detect").
393 395
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575 This can be used to signal any errors to the condition variable 577 This can be used to signal any errors to the condition variable
576 user/consumer. 578 user/consumer.
577 579
578 $cv->begin ([group callback]) 580 $cv->begin ([group callback])
579 $cv->end 581 $cv->end
580 These two methods are EXPERIMENTAL and MIGHT CHANGE.
581
582 These two methods can be used to combine many transactions/events 582 These two methods can be used to combine many transactions/events
583 into one. For example, a function that pings many hosts in parallel 583 into one. For example, a function that pings many hosts in parallel
584 might want to use a condition variable for the whole process. 584 might want to use a condition variable for the whole process.
585 585
586 Every call to "->begin" will increment a counter, and every call to 586 Every call to "->begin" will increment a counter, and every call to
587 "->end" will decrement it. If the counter reaches 0 in "->end", the 587 "->end" will decrement it. If the counter reaches 0 in "->end", the
588 (last) callback passed to "begin" will be executed. That callback is 588 (last) callback passed to "begin" will be executed. That callback is
589 *supposed* to call "->send", but that is not required. If no 589 *supposed* to call "->send", but that is not required. If no
590 callback was set, "send" will be called without any arguments. 590 callback was set, "send" will be called without any arguments.
591 591
592 Let's clarify this with the ping example: 592 You can think of "$cv->send" giving you an OR condition (one call
593 sends), while "$cv->begin" and "$cv->end" giving you an AND
594 condition (all "begin" calls must be "end"'ed before the condvar
595 sends).
596
597 Let's start with a simple example: you have two I/O watchers (for
598 example, STDOUT and STDERR for a program), and you want to wait for
599 both streams to close before activating a condvar:
600
601 my $cv = AnyEvent->condvar;
602
603 $cv->begin; # first watcher
604 my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
605 defined sysread $fh1, my $buf, 4096
606 or $cv->end;
607 });
608
609 $cv->begin; # second watcher
610 my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
611 defined sysread $fh2, my $buf, 4096
612 or $cv->end;
613 });
614
615 $cv->recv;
616
617 This works because for every event source (EOF on file handle),
618 there is one call to "begin", so the condvar waits for all calls to
619 "end" before sending.
620
621 The ping example mentioned above is slightly more complicated, as
622 the there are results to be passwd back, and the number of tasks
623 that are begung can potentially be zero:
593 624
594 my $cv = AnyEvent->condvar; 625 my $cv = AnyEvent->condvar;
595 626
596 my %result; 627 my %result;
597 $cv->begin (sub { $cv->send (\%result) }); 628 $cv->begin (sub { $cv->send (\%result) });
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617 the loop, which serves two important purposes: first, it sets the 648 the loop, which serves two important purposes: first, it sets the
618 callback to be called once the counter reaches 0, and second, it 649 callback to be called once the counter reaches 0, and second, it
619 ensures that "send" is called even when "no" hosts are being pinged 650 ensures that "send" is called even when "no" hosts are being pinged
620 (the loop doesn't execute once). 651 (the loop doesn't execute once).
621 652
622 This is the general pattern when you "fan out" into multiple 653 This is the general pattern when you "fan out" into multiple (but
623 subrequests: use an outer "begin"/"end" pair to set the callback and 654 potentially none) subrequests: use an outer "begin"/"end" pair to
624 ensure "end" is called at least once, and then, for each subrequest 655 set the callback and ensure "end" is called at least once, and then,
625 you start, call "begin" and for each subrequest you finish, call 656 for each subrequest you start, call "begin" and for each subrequest
626 "end". 657 you finish, call "end".
627 658
628 METHODS FOR CONSUMERS 659 METHODS FOR CONSUMERS
629 These methods should only be used by the consuming side, i.e. the code 660 These methods should only be used by the consuming side, i.e. the code
630 awaits the condition. 661 awaits the condition.
631 662
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678 The callback will be called when the condition becomes "true", i.e. 709 The callback will be called when the condition becomes "true", i.e.
679 when "send" or "croak" are called, with the only argument being the 710 when "send" or "croak" are called, with the only argument being the
680 condition variable itself. Calling "recv" inside the callback or at 711 condition variable itself. Calling "recv" inside the callback or at
681 any later time is guaranteed not to block. 712 any later time is guaranteed not to block.
682 713
714SUPPORTED EVENT LOOPS/BACKENDS
715 The available backend classes are (every class has its own manpage):
716
717 Backends that are autoprobed when no other event loop can be found.
718 EV is the preferred backend when no other event loop seems to be in
719 use. If EV is not installed, then AnyEvent will try Event, and,
720 failing that, will fall back to its own pure-perl implementation,
721 which is available everywhere as it comes with AnyEvent itself.
722
723 AnyEvent::Impl::EV based on EV (interface to libev, best choice).
724 AnyEvent::Impl::Event based on Event, very stable, few glitches.
725 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
726
727 Backends that are transparently being picked up when they are used.
728 These will be used when they are currently loaded when the first
729 watcher is created, in which case it is assumed that the application
730 is using them. This means that AnyEvent will automatically pick the
731 right backend when the main program loads an event module before
732 anything starts to create watchers. Nothing special needs to be done
733 by the main program.
734
735 AnyEvent::Impl::Glib based on Glib, slow but very stable.
736 AnyEvent::Impl::Tk based on Tk, very broken.
737 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
738 AnyEvent::Impl::POE based on POE, very slow, some limitations.
739
740 Backends with special needs.
741 Qt requires the Qt::Application to be instantiated first, but will
742 otherwise be picked up automatically. As long as the main program
743 instantiates the application before any AnyEvent watchers are
744 created, everything should just work.
745
746 AnyEvent::Impl::Qt based on Qt.
747
748 Support for IO::Async can only be partial, as it is too broken and
749 architecturally limited to even support the AnyEvent API. It also is
750 the only event loop that needs the loop to be set explicitly, so it
751 can only be used by a main program knowing about AnyEvent. See
752 AnyEvent::Impl::Async for the gory details.
753
754 AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
755
756 Event loops that are indirectly supported via other backends.
757 Some event loops can be supported via other modules:
758
759 There is no direct support for WxWidgets (Wx) or Prima.
760
761 WxWidgets has no support for watching file handles. However, you can
762 use WxWidgets through the POE adaptor, as POE has a Wx backend that
763 simply polls 20 times per second, which was considered to be too
764 horrible to even consider for AnyEvent.
765
766 Prima is not supported as nobody seems to be using it, but it has a
767 POE backend, so it can be supported through POE.
768
769 AnyEvent knows about both Prima and Wx, however, and will try to
770 load POE when detecting them, in the hope that POE will pick them
771 up, in which case everything will be automatic.
772
683GLOBAL VARIABLES AND FUNCTIONS 773GLOBAL VARIABLES AND FUNCTIONS
774 These are not normally required to use AnyEvent, but can be useful to
775 write AnyEvent extension modules.
776
684 $AnyEvent::MODEL 777 $AnyEvent::MODEL
685 Contains "undef" until the first watcher is being created. Then it 778 Contains "undef" until the first watcher is being created, before
779 the backend has been autodetected.
780
686 contains the event model that is being used, which is the name of 781 Afterwards it contains the event model that is being used, which is
687 the Perl class implementing the model. This class is usually one of 782 the name of the Perl class implementing the model. This class is
688 the "AnyEvent::Impl:xxx" modules, but can be any other class in the 783 usually one of the "AnyEvent::Impl:xxx" modules, but can be any
689 case AnyEvent has been extended at runtime (e.g. in *rxvt-unicode*). 784 other class in the case AnyEvent has been extended at runtime (e.g.
690 785 in *rxvt-unicode* it will be "urxvt::anyevent").
691 The known classes so far are:
692
693 AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
694 AnyEvent::Impl::Event based on Event, second best choice.
695 AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
696 AnyEvent::Impl::Glib based on Glib, third-best choice.
697 AnyEvent::Impl::Tk based on Tk, very bad choice.
698 AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
699 AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
700 AnyEvent::Impl::POE based on POE, not generic enough for full support.
701
702 There is no support for WxWidgets, as WxWidgets has no support for
703 watching file handles. However, you can use WxWidgets through the
704 POE Adaptor, as POE has a Wx backend that simply polls 20 times per
705 second, which was considered to be too horrible to even consider for
706 AnyEvent. Likewise, other POE backends can be used by AnyEvent by
707 using it's adaptor.
708
709 AnyEvent knows about Prima and Wx and will try to use POE when
710 autodetecting them.
711 786
712 AnyEvent::detect 787 AnyEvent::detect
713 Returns $AnyEvent::MODEL, forcing autodetection of the event model 788 Returns $AnyEvent::MODEL, forcing autodetection of the event model
714 if necessary. You should only call this function right before you 789 if necessary. You should only call this function right before you
715 would have created an AnyEvent watcher anyway, that is, as late as 790 would have created an AnyEvent watcher anyway, that is, as late as
716 possible at runtime. 791 possible at runtime, and not e.g. while initialising of your module.
792
793 If you need to do some initialisation before AnyEvent watchers are
794 created, use "post_detect".
717 795
718 $guard = AnyEvent::post_detect { BLOCK } 796 $guard = AnyEvent::post_detect { BLOCK }
719 Arranges for the code block to be executed as soon as the event 797 Arranges for the code block to be executed as soon as the event
720 model is autodetected (or immediately if this has already happened). 798 model is autodetected (or immediately if this has already happened).
799
800 The block will be executed *after* the actual backend has been
801 detected ($AnyEvent::MODEL is set), but *before* any watchers have
802 been created, so it is possible to e.g. patch @AnyEvent::ISA or do
803 other initialisations - see the sources of AnyEvent::Strict or
804 AnyEvent::AIO to see how this is used.
805
806 The most common usage is to create some global watchers, without
807 forcing event module detection too early, for example, AnyEvent::AIO
808 creates and installs the global IO::AIO watcher in a "post_detect"
809 block to avoid autodetecting the event module at load time.
721 810
722 If called in scalar or list context, then it creates and returns an 811 If called in scalar or list context, then it creates and returns an
723 object that automatically removes the callback again when it is 812 object that automatically removes the callback again when it is
724 destroyed. See Coro::BDB for a case where this is useful. 813 destroyed. See Coro::BDB for a case where this is useful.
725 814
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727 If there are any code references in this array (you can "push" to it 816 If there are any code references in this array (you can "push" to it
728 before or after loading AnyEvent), then they will called directly 817 before or after loading AnyEvent), then they will called directly
729 after the event loop has been chosen. 818 after the event loop has been chosen.
730 819
731 You should check $AnyEvent::MODEL before adding to this array, 820 You should check $AnyEvent::MODEL before adding to this array,
732 though: if it contains a true value then the event loop has already 821 though: if it is defined then the event loop has already been
733 been detected, and the array will be ignored. 822 detected, and the array will be ignored.
734 823
735 Best use "AnyEvent::post_detect { BLOCK }" instead. 824 Best use "AnyEvent::post_detect { BLOCK }" when your application
825 allows it,as it takes care of these details.
826
827 This variable is mainly useful for modules that can do something
828 useful when AnyEvent is used and thus want to know when it is
829 initialised, but do not need to even load it by default. This array
830 provides the means to hook into AnyEvent passively, without loading
831 it.
736 832
737WHAT TO DO IN A MODULE 833WHAT TO DO IN A MODULE
738 As a module author, you should "use AnyEvent" and call AnyEvent methods 834 As a module author, you should "use AnyEvent" and call AnyEvent methods
739 freely, but you should not load a specific event module or rely on it. 835 freely, but you should not load a specific event module or rely on it.
740 836
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791 variable somewhere, waiting for it, and sending it when the program 887 variable somewhere, waiting for it, and sending it when the program
792 should exit cleanly. 888 should exit cleanly.
793 889
794OTHER MODULES 890OTHER MODULES
795 The following is a non-exhaustive list of additional modules that use 891 The following is a non-exhaustive list of additional modules that use
796 AnyEvent and can therefore be mixed easily with other AnyEvent modules 892 AnyEvent as a client and can therefore be mixed easily with other
797 in the same program. Some of the modules come with AnyEvent, some are 893 AnyEvent modules and other event loops in the same program. Some of the
798 available via CPAN. 894 modules come with AnyEvent, most are available via CPAN.
799 895
800 AnyEvent::Util 896 AnyEvent::Util
801 Contains various utility functions that replace often-used but 897 Contains various utility functions that replace often-used but
802 blocking functions such as "inet_aton" by event-/callback-based 898 blocking functions such as "inet_aton" by event-/callback-based
803 versions. 899 versions.
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809 more. 905 more.
810 906
811 AnyEvent::Handle 907 AnyEvent::Handle
812 Provide read and write buffers, manages watchers for reads and 908 Provide read and write buffers, manages watchers for reads and
813 writes, supports raw and formatted I/O, I/O queued and fully 909 writes, supports raw and formatted I/O, I/O queued and fully
814 transparent and non-blocking SSL/TLS. 910 transparent and non-blocking SSL/TLS (via AnyEvent::TLS.
815 911
816 AnyEvent::DNS 912 AnyEvent::DNS
817 Provides rich asynchronous DNS resolver capabilities. 913 Provides rich asynchronous DNS resolver capabilities.
818 914
819 AnyEvent::HTTP 915 AnyEvent::HTTP
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840 936
841 AnyEvent::GPSD 937 AnyEvent::GPSD
842 A non-blocking interface to gpsd, a daemon delivering GPS 938 A non-blocking interface to gpsd, a daemon delivering GPS
843 information. 939 information.
844 940
941 AnyEvent::IRC
942 AnyEvent based IRC client module family (replacing the older
943 Net::IRC3).
944
945 AnyEvent::XMPP
946 AnyEvent based XMPP (Jabber protocol) module family (replacing the
947 older Net::XMPP2>.
948
845 AnyEvent::IGS 949 AnyEvent::IGS
846 A non-blocking interface to the Internet Go Server protocol (used by 950 A non-blocking interface to the Internet Go Server protocol (used by
847 App::IGS). 951 App::IGS).
848 952
849 AnyEvent::IRC
850 AnyEvent based IRC client module family (replacing the older
851 Net::IRC3).
852
853 Net::XMPP2
854 AnyEvent based XMPP (Jabber protocol) module family.
855
856 Net::FCP 953 Net::FCP
857 AnyEvent-based implementation of the Freenet Client Protocol, 954 AnyEvent-based implementation of the Freenet Client Protocol,
858 birthplace of AnyEvent. 955 birthplace of AnyEvent.
859 956
860 Event::ExecFlow 957 Event::ExecFlow
861 High level API for event-based execution flow control. 958 High level API for event-based execution flow control.
862 959
863 Coro 960 Coro
864 Has special support for AnyEvent via Coro::AnyEvent. 961 Has special support for AnyEvent via Coro::AnyEvent.
865
866 IO::Lambda
867 The lambda approach to I/O - don't ask, look there. Can use
868 AnyEvent.
869 962
870ERROR AND EXCEPTION HANDLING 963ERROR AND EXCEPTION HANDLING
871 In general, AnyEvent does not do any error handling - it relies on the 964 In general, AnyEvent does not do any error handling - it relies on the
872 caller to do that if required. The AnyEvent::Strict module (see also the 965 caller to do that if required. The AnyEvent::Strict module (see also the
873 "PERL_ANYEVENT_STRICT" environment variable, below) provides strict 966 "PERL_ANYEVENT_STRICT" environment variable, below) provides strict
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906 "PERL_ANYEVENT_STRICT" 999 "PERL_ANYEVENT_STRICT"
907 AnyEvent does not do much argument checking by default, as thorough 1000 AnyEvent does not do much argument checking by default, as thorough
908 argument checking is very costly. Setting this variable to a true 1001 argument checking is very costly. Setting this variable to a true
909 value will cause AnyEvent to load "AnyEvent::Strict" and then to 1002 value will cause AnyEvent to load "AnyEvent::Strict" and then to
910 thoroughly check the arguments passed to most method calls. If it 1003 thoroughly check the arguments passed to most method calls. If it
911 finds any problems it will croak. 1004 finds any problems, it will croak.
912 1005
913 In other words, enables "strict" mode. 1006 In other words, enables "strict" mode.
914 1007
915 Unlike "use strict", it is definitely recommended ot keep it off in 1008 Unlike "use strict", it is definitely recommended to keep it off in
916 production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment 1009 production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment
917 while developing programs can be very useful, however. 1010 while developing programs can be very useful, however.
918 1011
919 "PERL_ANYEVENT_MODEL" 1012 "PERL_ANYEVENT_MODEL"
920 This can be used to specify the event model to be used by AnyEvent, 1013 This can be used to specify the event model to be used by AnyEvent,
… …
963 EDNS0 in its DNS requests. 1056 EDNS0 in its DNS requests.
964 1057
965 "PERL_ANYEVENT_MAX_FORKS" 1058 "PERL_ANYEVENT_MAX_FORKS"
966 The maximum number of child processes that 1059 The maximum number of child processes that
967 "AnyEvent::Util::fork_call" will create in parallel. 1060 "AnyEvent::Util::fork_call" will create in parallel.
1061
1062 "PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
1063 The default value for the "max_outstanding" parameter for the
1064 default DNS resolver - this is the maximum number of parallel DNS
1065 requests that are sent to the DNS server.
1066
1067 "PERL_ANYEVENT_RESOLV_CONF"
1068 The file to use instead of /etc/resolv.conf (or OS-specific
1069 configuration) in the default resolver. When set to the empty
1070 string, no default config will be used.
1071
1072 "PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
1073 When neither "ca_file" nor "ca_path" was specified during
1074 AnyEvent::TLS context creation, and either of these environment
1075 variables exist, they will be used to specify CA certificate
1076 locations instead of a system-dependent default.
968 1077
969SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1078SUPPLYING YOUR OWN EVENT MODEL INTERFACE
970 This is an advanced topic that you do not normally need to use AnyEvent 1079 This is an advanced topic that you do not normally need to use AnyEvent
971 in a module. This section is only of use to event loop authors who want 1080 in a module. This section is only of use to event loop authors who want
972 to provide AnyEvent compatibility. 1081 to provide AnyEvent compatibility.
… …
1208 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers 1317 EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1209 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal 1318 CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1210 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation 1319 Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1211 Event/Event 16000 517 32.20 31.80 0.81 Event native interface 1320 Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1212 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers 1321 Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1322 IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
1323 IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1213 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour 1324 Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1214 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers 1325 Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1215 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event 1326 POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1216 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select 1327 POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1217 1328
… …
1246 few of them active), of course, but this was not subject of this 1357 few of them active), of course, but this was not subject of this
1247 benchmark. 1358 benchmark.
1248 1359
1249 The "Event" module has a relatively high setup and callback invocation 1360 The "Event" module has a relatively high setup and callback invocation
1250 cost, but overall scores in on the third place. 1361 cost, but overall scores in on the third place.
1362
1363 "IO::Async" performs admirably well, about on par with "Event", even
1364 when using its pure perl backend.
1251 1365
1252 "Glib"'s memory usage is quite a bit higher, but it features a faster 1366 "Glib"'s memory usage is quite a bit higher, but it features a faster
1253 callback invocation and overall ends up in the same class as "Event". 1367 callback invocation and overall ends up in the same class as "Event".
1254 However, Glib scales extremely badly, doubling the number of watchers 1368 However, Glib scales extremely badly, doubling the number of watchers
1255 increases the processing time by more than a factor of four, making it 1369 increases the processing time by more than a factor of four, making it
… …
1326 single "request", that is, reading the token from the pipe and 1440 single "request", that is, reading the token from the pipe and
1327 forwarding it to another server. This includes deleting the old timeout 1441 forwarding it to another server. This includes deleting the old timeout
1328 and creating a new one that moves the timeout into the future. 1442 and creating a new one that moves the timeout into the future.
1329 1443
1330 Results 1444 Results
1331 name sockets create request 1445 name sockets create request
1332 EV 20000 69.01 11.16 1446 EV 20000 69.01 11.16
1333 Perl 20000 73.32 35.87 1447 Perl 20000 73.32 35.87
1448 IOAsync 20000 157.00 98.14 epoll
1449 IOAsync 20000 159.31 616.06 poll
1334 Event 20000 212.62 257.32 1450 Event 20000 212.62 257.32
1335 Glib 20000 651.16 1896.30 1451 Glib 20000 651.16 1896.30
1336 POE 20000 349.67 12317.24 uses POE::Loop::Event 1452 POE 20000 349.67 12317.24 uses POE::Loop::Event
1337 1453
1338 Discussion 1454 Discussion
1339 This benchmark *does* measure scalability and overall performance of the 1455 This benchmark *does* measure scalability and overall performance of the
1340 particular event loop. 1456 particular event loop.
1341 1457
1342 EV is again fastest. Since it is using epoll on my system, the setup 1458 EV is again fastest. Since it is using epoll on my system, the setup
1343 time is relatively high, though. 1459 time is relatively high, though.
1344 1460
1345 Perl surprisingly comes second. It is much faster than the C-based event 1461 Perl surprisingly comes second. It is much faster than the C-based event
1346 loops Event and Glib. 1462 loops Event and Glib.
1463
1464 IO::Async performs very well when using its epoll backend, and still
1465 quite good compared to Glib when using its pure perl backend.
1347 1466
1348 Event suffers from high setup time as well (look at its code and you 1467 Event suffers from high setup time as well (look at its code and you
1349 will understand why). Callback invocation also has a high overhead 1468 will understand why). Callback invocation also has a high overhead
1350 compared to the "$_->() for .."-style loop that the Perl event loop 1469 compared to the "$_->() for .."-style loop that the Perl event loop
1351 uses. Event uses select or poll in basically all documented 1470 uses. Event uses select or poll in basically all documented
… …
1407 THE IO::Lambda BENCHMARK 1526 THE IO::Lambda BENCHMARK
1408 Recently I was told about the benchmark in the IO::Lambda manpage, which 1527 Recently I was told about the benchmark in the IO::Lambda manpage, which
1409 could be misinterpreted to make AnyEvent look bad. In fact, the 1528 could be misinterpreted to make AnyEvent look bad. In fact, the
1410 benchmark simply compares IO::Lambda with POE, and IO::Lambda looks 1529 benchmark simply compares IO::Lambda with POE, and IO::Lambda looks
1411 better (which shouldn't come as a surprise to anybody). As such, the 1530 better (which shouldn't come as a surprise to anybody). As such, the
1412 benchmark is fine, and shows that the AnyEvent backend from IO::Lambda 1531 benchmark is fine, and mostly shows that the AnyEvent backend from
1413 isn't very optimal. But how would AnyEvent compare when used without the 1532 IO::Lambda isn't very optimal. But how would AnyEvent compare when used
1414 extra baggage? To explore this, I wrote the equivalent benchmark for 1533 without the extra baggage? To explore this, I wrote the equivalent
1415 AnyEvent. 1534 benchmark for AnyEvent.
1416 1535
1417 The benchmark itself creates an echo-server, and then, for 500 times, 1536 The benchmark itself creates an echo-server, and then, for 500 times,
1418 connects to the echo server, sends a line, waits for the reply, and then 1537 connects to the echo server, sends a line, waits for the reply, and then
1419 creates the next connection. This is a rather bad benchmark, as it 1538 creates the next connection. This is a rather bad benchmark, as it
1420 doesn't test the efficiency of the framework, but it is a benchmark 1539 doesn't test the efficiency of the framework or much non-blocking I/O,
1421 nevertheless. 1540 but it is a benchmark nevertheless.
1422 1541
1423 name runtime 1542 name runtime
1424 Lambda/select 0.330 sec 1543 Lambda/select 0.330 sec
1425 + optimized 0.122 sec 1544 + optimized 0.122 sec
1426 Lambda/AnyEvent 0.327 sec 1545 Lambda/AnyEvent 0.327 sec
… …
1432 1551
1433 AnyEvent/select/nb 0.085 sec 1552 AnyEvent/select/nb 0.085 sec
1434 AnyEvent/EV/nb 0.068 sec 1553 AnyEvent/EV/nb 0.068 sec
1435 +state machine 0.134 sec 1554 +state machine 0.134 sec
1436 1555
1437 The benchmark is also a bit unfair (my fault) - the IO::Lambda 1556 The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
1438 benchmarks actually make blocking connects and use 100% blocking I/O, 1557 benchmarks actually make blocking connects and use 100% blocking I/O,
1439 defeating the purpose of an event-based solution. All of the newly 1558 defeating the purpose of an event-based solution. All of the newly
1440 written AnyEvent benchmarks use 100% non-blocking connects (using 1559 written AnyEvent benchmarks use 100% non-blocking connects (using
1441 AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS 1560 AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
1442 resolver), so AnyEvent is at a disadvantage here as non-blocking 1561 resolver), so AnyEvent is at a disadvantage here, as non-blocking
1443 connects generally require a lot more bookkeeping and event handling 1562 connects generally require a lot more bookkeeping and event handling
1444 than blocking connects (which involve a single syscall only). 1563 than blocking connects (which involve a single syscall only).
1445 1564
1446 The last AnyEvent benchmark additionally uses AnyEvent::Handle, which 1565 The last AnyEvent benchmark additionally uses AnyEvent::Handle, which
1447 offers similar expressive power as POE and IO::Lambda (using 1566 offers similar expressive power as POE and IO::Lambda, using
1448 conventional Perl syntax), which means both the echo server and the 1567 conventional Perl syntax. This means that both the echo server and the
1449 client are 100% non-blocking w.r.t. I/O, further placing it at a 1568 client are 100% non-blocking, further placing it at a disadvantage.
1450 disadvantage.
1451 1569
1452 As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets 1570 As you can see, the AnyEvent + EV combination even beats the
1453 benchmark", while AnyEvent + its pure perl backend easily beats 1571 hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1454 IO::Lambda and POE. 1572 backend easily beats IO::Lambda and POE.
1455 1573
1456 And even the 100% non-blocking version written using the high-level (and 1574 And even the 100% non-blocking version written using the high-level (and
1457 slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda, even 1575 slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a
1458 thought it does all of DNS, tcp-connect and socket I/O in a non-blocking 1576 large margin, even though it does all of DNS, tcp-connect and socket I/O
1459 way. 1577 in a non-blocking way.
1460 1578
1461 The two AnyEvent benchmarks can be found as eg/ae0.pl and eg/ae2.pl in 1579 The two AnyEvent benchmarks programs can be found as eg/ae0.pl and
1462 the AnyEvent distribution, the remaining benchmarks are part of the 1580 eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
1463 IO::lambda distribution and were used without any changes. 1581 part of the IO::lambda distribution and were used without any changes.
1464 1582
1465SIGNALS 1583SIGNALS
1466 AnyEvent currently installs handlers for these signals: 1584 AnyEvent currently installs handlers for these signals:
1467 1585
1468 SIGCHLD 1586 SIGCHLD
1469 A handler for "SIGCHLD" is installed by AnyEvent's child watcher 1587 A handler for "SIGCHLD" is installed by AnyEvent's child watcher
1470 emulation for event loops that do not support them natively. Also, 1588 emulation for event loops that do not support them natively. Also,
1471 some event loops install a similar handler. 1589 some event loops install a similar handler.
1590
1591 If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent
1592 will reset it to default, to avoid losing child exit statuses.
1472 1593
1473 SIGPIPE 1594 SIGPIPE
1474 A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is 1595 A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is
1475 "undef" when AnyEvent gets loaded. 1596 "undef" when AnyEvent gets loaded.
1476 1597
… …
1512 Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can 1633 Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1513 be used to probe what backend is used and gain other information (which 1634 be used to probe what backend is used and gain other information (which
1514 is probably even less useful to an attacker than PERL_ANYEVENT_MODEL), 1635 is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),
1515 and $ENV{PERL_ANYEVENT_STRICT}. 1636 and $ENV{PERL_ANYEVENT_STRICT}.
1516 1637
1638 Note that AnyEvent will remove *all* environment variables starting with
1639 "PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is
1640 enabled.
1641
1517BUGS 1642BUGS
1518 Perl 5.8 has numerous memleaks that sometimes hit this module and are 1643 Perl 5.8 has numerous memleaks that sometimes hit this module and are
1519 hard to work around. If you suffer from memleaks, first upgrade to Perl 1644 hard to work around. If you suffer from memleaks, first upgrade to Perl
1520 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other 1645 5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1521 annoying memleaks, such as leaking on "map" and "grep" but it is usually 1646 annoying memleaks, such as leaking on "map" and "grep" but it is usually
… …
1527 Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk, 1652 Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
1528 Event::Lib, Qt, POE. 1653 Event::Lib, Qt, POE.
1529 1654
1530 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event, 1655 Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1531 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, 1656 AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1532 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE. 1657 AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
1658 AnyEvent::Impl::IOAsync.
1533 1659
1534 Non-blocking file handles, sockets, TCP clients and servers: 1660 Non-blocking file handles, sockets, TCP clients and servers:
1535 AnyEvent::Handle, AnyEvent::Socket. 1661 AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1536 1662
1537 Asynchronous DNS: AnyEvent::DNS. 1663 Asynchronous DNS: AnyEvent::DNS.
1538 1664
1539 Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event, 1665 Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,
1540 1666
1541 Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS. 1667 Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,
1668 AnyEvent::HTTP.
1542 1669
1543AUTHOR 1670AUTHOR
1544 Marc Lehmann <schmorp@schmorp.de> 1671 Marc Lehmann <schmorp@schmorp.de>
1545 http://home.schmorp.de/ 1672 http://home.schmorp.de/
1546 1673

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