--- AnyEvent/lib/AnyEvent.pm 2008/04/26 04:19:52 1.93 +++ AnyEvent/lib/AnyEvent.pm 2008/04/30 11:40:22 1.104 @@ -68,7 +68,6 @@ useful) and you want to force your users to use the one and only event model, you should I use this module. - =head1 DESCRIPTION L provides an identical interface to multiple event loops. This @@ -393,8 +392,8 @@ AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice. AnyEvent::Impl::EV based on EV (an interface to libev, best choice). AnyEvent::Impl::Event based on Event, second best choice. + AnyEvent::Impl::Perl pure-perl implementation, fast and portable. AnyEvent::Impl::Glib based on Glib, third-best choice. - AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable. AnyEvent::Impl::Tk based on Tk, very bad choice. AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs). AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse. @@ -460,6 +459,78 @@ loading the C module, which gives you similar behaviour everywhere, but letting AnyEvent chose is generally better. +=head1 OTHER MODULES + +The following is a non-exhaustive list of additional modules that use +AnyEvent and can therefore be mixed easily with other AnyEvent modules +in the same program. Some of the modules come with AnyEvent, some are +available via CPAN. + +=over 4 + +=item L + +Contains various utility functions that replace often-used but blocking +functions such as C by event-/callback-based versions. + +=item L + +Provide read and write buffers and manages watchers for reads and writes. + +=item L + +Provides a means to do non-blocking connects, accepts etc. + +=item L + +Provides a simple web application server framework. + +=item L + +Provides asynchronous DNS resolver capabilities, beyond what +L offers. + +=item L + +The fastest ping in the west. + +=item L + +AnyEvent based IRC client module family. + +=item L + +AnyEvent based XMPP (Jabber protocol) module family. + +=item L + +AnyEvent-based implementation of the Freenet Client Protocol, birthplace +of AnyEvent. + +=item L + +High level API for event-based execution flow control. + +=item L + +Has special support for AnyEvent. + +=item L + +The lambda approach to I/O - don't ask, look there. Can use AnyEvent. + +=item L + +Truly asynchronous I/O, should be in the toolbox of every event +programmer. Can be trivially made to use AnyEvent. + +=item L + +Truly asynchronous Berkeley DB access. Can be trivially made to use +AnyEvent. + +=back + =cut package AnyEvent; @@ -484,12 +555,12 @@ [Coro::Event:: => AnyEvent::Impl::CoroEvent::], [EV:: => AnyEvent::Impl::EV::], [Event:: => AnyEvent::Impl::Event::], - [Glib:: => AnyEvent::Impl::Glib::], [Tk:: => AnyEvent::Impl::Tk::], [Wx:: => AnyEvent::Impl::POE::], [Prima:: => AnyEvent::Impl::POE::], [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], # everything below here will not be autoprobed as the pureperl backend should work everywhere + [Glib:: => AnyEvent::Impl::Glib::], [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy [Qt:: => AnyEvent::Impl::Qt::], # requires special main program [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza @@ -946,7 +1017,7 @@ CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation Event/Event 16000 516 31.88 31.30 0.85 Event native interface - Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers + Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event @@ -961,6 +1032,16 @@ the same time, so select/poll-based implementations get an unnatural speed boost. +Also, note that the number of watchers usually has a nonlinear effect on +overall speed, that is, creating twice as many watchers doesn't take twice +the time - usually it takes longer. This puts event loops tested with a +higher number of watchers at a disadvantage. + +To put the range of results into perspective, consider that on the +benchmark machine, handling an event takes roughly 1600 CPU cycles with +EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU +cycles with POE. + C is the sole leader regarding speed and memory use, which are both maximal/minimal, respectively. Even when going through AnyEvent, it uses far less memory than any other event loop and is still faster than Event @@ -992,17 +1073,22 @@ hidden memory cost inside the kernel which is not reflected in the figures above). -C, regardless of underlying event loop (whether using its pure -perl select-based backend or the Event module, the POE-EV backend -couldn't be tested because it wasn't working) shows abysmal performance -and memory usage: Watchers use almost 30 times as much memory as -EV watchers, and 10 times as much memory as Event (the high memory +C, regardless of underlying event loop (whether using its pure perl +select-based backend or the Event module, the POE-EV backend couldn't +be tested because it wasn't working) shows abysmal performance and +memory usage with AnyEvent: Watchers use almost 30 times as much memory +as EV watchers, and 10 times as much memory as Event (the high memory requirements are caused by requiring a session for each watcher). Watcher invocation speed is almost 900 times slower than with AnyEvent's pure perl -implementation. The design of the POE adaptor class in AnyEvent can not -really account for this, as session creation overhead is small compared -to execution of the state machine, which is coded pretty optimally within -L. POE simply seems to be abysmally slow. +implementation. + +The design of the POE adaptor class in AnyEvent can not really account +for the performance issues, though, as session creation overhead is +small compared to execution of the state machine, which is coded pretty +optimally within L (and while everybody agrees that +using multiple sessions is not a good approach, especially regarding +memory usage, even the author of POE could not come up with a faster +design). =head3 Summary @@ -1045,7 +1131,7 @@ =head3 Explanation of the columns I is the number of sockets, and twice the number of "servers" (as -eahc server has a read and write socket end). +each server has a read and write socket end). I is the time it takes to create a socketpair (which is nontrivial) and two watchers: an I/O watcher and a timeout watcher. @@ -1059,7 +1145,7 @@ name sockets create request EV 20000 69.01 11.16 - Perl 20000 75.28 112.76 + Perl 20000 73.32 35.87 Event 20000 212.62 257.32 Glib 20000 651.16 1896.30 POE 20000 349.67 12317.24 uses POE::Loop::Event @@ -1091,8 +1177,7 @@ =over 4 -=item * The pure perl implementation performs extremely well, considering -that it uses select. +=item * The pure perl implementation performs extremely well. =item * Avoid Glib or POE in large projects where performance matters. @@ -1115,9 +1200,9 @@ name sockets create request EV 16 20.00 6.54 + Perl 16 25.75 12.62 Event 16 81.27 35.86 Glib 16 32.63 15.48 - Perl 16 24.62 162.37 POE 16 261.87 276.28 uses POE::Loop::Event =head3 Discussion @@ -1125,18 +1210,17 @@ The benchmark tries to test the performance of a typical small server. While knowing how various event loops perform is interesting, keep in mind that their overhead in this case is usually not as important, due -to the small absolute number of watchers. +to the small absolute number of watchers (that is, you need efficiency and +speed most when you have lots of watchers, not when you only have a few of +them). EV is again fastest. -The C-based event loops Event and Glib come in second this time, as the -overhead of running an iteration is much smaller in C than in Perl (little -code to execute in the inner loop, and perl's function calling overhead is -high, and updating all the data structures is costly). - -The pure perl event loop is much slower, but still competitive. +Perl again comes second. It is noticably faster than the C-based event +loops Event and Glib, although the difference is too small to really +matter. -POE also performs much better in this case, but is is stillf ar behind the +POE also performs much better in this case, but is is still far behind the others. =head3 Summary @@ -1152,7 +1236,8 @@ =head1 FORK Most event libraries are not fork-safe. The ones who are usually are -because they are so inefficient. Only L is fully fork-aware. +because they rely on inefficient but fork-safe C