| … | |
… | |
| 864 | |
864 | |
| 865 | |
865 | |
| 866 | =head1 BENCHMARK |
866 | =head1 BENCHMARK |
| 867 | |
867 | |
| 868 | To give you an idea of the performance and overheads that AnyEvent adds |
868 | To give you an idea of the performance and overheads that AnyEvent adds |
|
|
869 | over the event loops themselves (and to give you an impression of the |
| 869 | over the event loops directly, here is a benchmark of various supported |
870 | speed of various event loops), here is a benchmark of various supported |
| 870 | event models natively and with anyevent. The benchmark creates a lot of |
871 | event models natively and with anyevent. The benchmark creates a lot of |
| 871 | timers (with a zero timeout) and io watchers (watching STDOUT, a pty, to |
872 | timers (with a zero timeout) and io watchers (watching STDOUT, a pty, to |
| 872 | become writable, which it is), lets them fire exactly once and destroys |
873 | become writable, which it is), lets them fire exactly once and destroys |
| 873 | them again. |
874 | them again. |
| 874 | |
875 | |
| … | |
… | |
| 893 | I<invoke> is the time, in microseconds, used to invoke a simple |
894 | I<invoke> is the time, in microseconds, used to invoke a simple |
| 894 | callback. The callback simply counts down a Perl variable and after it was |
895 | callback. The callback simply counts down a Perl variable and after it was |
| 895 | invoked "watcher" times, it would C<< ->broadcast >> a condvar once to |
896 | invoked "watcher" times, it would C<< ->broadcast >> a condvar once to |
| 896 | signal the end of this phase. |
897 | signal the end of this phase. |
| 897 | |
898 | |
| 898 | I<destroy> is the time, in microseconds, that it takes destroy a single |
899 | I<destroy> is the time, in microseconds, that it takes to destroy a single |
| 899 | watcher. |
900 | watcher. |
| 900 | |
901 | |
| 901 | =head2 Results |
902 | =head2 Results |
| 902 | |
903 | |
| 903 | name watcher bytes create invoke destroy comment |
904 | name watcher bytes create invoke destroy comment |
| … | |
… | |
| 944 | precedence over speed. Nevertheless, its performance is surprising, as the |
945 | precedence over speed. Nevertheless, its performance is surprising, as the |
| 945 | file descriptor is dup()ed for each watcher. This shows that the dup() |
946 | file descriptor is dup()ed for each watcher. This shows that the dup() |
| 946 | employed by some adaptors is not a big performance issue (it does incur a |
947 | employed by some adaptors is not a big performance issue (it does incur a |
| 947 | hidden memory cost inside the kernel, though). |
948 | hidden memory cost inside the kernel, though). |
| 948 | |
949 | |
| 949 | C<POE>, regardless of backend (wether using its pure perl select-based |
950 | C<POE>, regardless of underlying event loop (wether using its pure perl |
| 950 | backend or the Event backend) shows abysmal performance and memory |
951 | select-based backend or the Event module) shows abysmal performance and |
| 951 | usage: Watchers use almost 30 times as much memory as EV watchers, and 10 |
952 | memory usage: Watchers use almost 30 times as much memory as EV watchers, |
| 952 | times as much memory as both Event or EV via AnyEvent. Watcher invocation |
953 | and 10 times as much memory as both Event or EV via AnyEvent. Watcher |
| 953 | is almost 700 times slower as with AnyEvent's pure perl implementation. |
954 | invocation is almost 700 times slower than with AnyEvent's pure perl |
|
|
955 | implementation. The design of the POE adaptor class in AnyEvent can not |
|
|
956 | really account for this, as session creation overhead is small compared |
|
|
957 | to execution of the state machine, which is coded pretty optimally within |
|
|
958 | L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow. |
| 954 | |
959 | |
|
|
960 | =head2 Summary |
|
|
961 | |
| 955 | Summary: using EV through AnyEvent is faster than any other event |
962 | Using EV through AnyEvent is faster than any other event loop, but most |
| 956 | loop. The overhead AnyEvent adds can be very small, and you should avoid |
963 | event loops have acceptable performance with or without AnyEvent. |
| 957 | POE like the plague if you want performance or reasonable memory usage. |
964 | |
|
|
965 | The overhead AnyEvent adds is usually much smaller than the overhead of |
|
|
966 | the actual event loop, only with extremely fast event loops such as the EV |
|
|
967 | adds Anyevent significant overhead. |
|
|
968 | |
|
|
969 | And you should simply avoid POE like the plague if you want performance or |
|
|
970 | reasonable memory usage. |
| 958 | |
971 | |
| 959 | |
972 | |
| 960 | =head1 FORK |
973 | =head1 FORK |
| 961 | |
974 | |
| 962 | Most event libraries are not fork-safe. The ones who are usually are |
975 | Most event libraries are not fork-safe. The ones who are usually are |
