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Revision 1.76 by root, Fri Apr 25 08:41:38 2008 UTC vs.
Revision 1.78 by root, Fri Apr 25 09:06:27 2008 UTC

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136 136
137Note that C<my $w; $w => combination. This is necessary because in Perl, 137Note that C<my $w; $w => combination. This is necessary because in Perl,
138my variables are only visible after the statement in which they are 138my variables are only visible after the statement in which they are
139declared. 139declared.
140 140
141=head2 IO WATCHERS 141=head2 I/O WATCHERS
142 142
143You can create an I/O watcher by calling the C<< AnyEvent->io >> method 143You can create an I/O watcher by calling the C<< AnyEvent->io >> method
144with the following mandatory key-value pairs as arguments: 144with the following mandatory key-value pairs as arguments:
145 145
146C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for 146C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
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706 706
707=back 707=back
708 708
709=head1 EXAMPLE PROGRAM 709=head1 EXAMPLE PROGRAM
710 710
711The following program uses an IO watcher to read data from STDIN, a timer 711The following program uses an I/O watcher to read data from STDIN, a timer
712to display a message once per second, and a condition variable to quit the 712to display a message once per second, and a condition variable to quit the
713program when the user enters quit: 713program when the user enters quit:
714 714
715 use AnyEvent; 715 use AnyEvent;
716 716
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867 867
868To give you an idea of the performance and overheads that AnyEvent adds 868To give you an idea of the performance and overheads that AnyEvent adds
869over the event loops themselves (and to give you an impression of the 869over the event loops themselves (and to give you an impression of the
870speed of various event loops), here is a benchmark of various supported 870speed of various event loops), here is a benchmark of various supported
871event models natively and with anyevent. The benchmark creates a lot of 871event models natively and with anyevent. The benchmark creates a lot of
872timers (with a zero timeout) and io watchers (watching STDOUT, a pty, to 872timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to
873become writable, which it is), lets them fire exactly once and destroys 873become writable, which it is), lets them fire exactly once and destroys
874them again. 874them again.
875
876Rewriting the benchmark to use many different sockets instead of using
877the same filehandle for all I/O watchers results in a much longer runtime
878(socket creation is expensive), but qualitatively the same figures, so it
879was not used.
875 880
876=head2 Explanation of the columns 881=head2 Explanation of the columns
877 882
878I<watcher> is the number of event watchers created/destroyed. Since 883I<watcher> is the number of event watchers created/destroyed. Since
879different event models feature vastly different performances, each event 884different event models feature vastly different performances, each event
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928natively and the pure perl backend), and no faster event models, not even 933natively and the pure perl backend), and no faster event models, not even
929C<Event> natively. 934C<Event> natively.
930 935
931The pure perl implementation is hit in a few sweet spots (both the 936The pure perl implementation is hit in a few sweet spots (both the
932zero timeout and the use of a single fd hit optimisations in the perl 937zero timeout and the use of a single fd hit optimisations in the perl
933interpreter and the backend itself). Nevertheless tis shows that it 938interpreter and the backend itself, and all watchers become ready at the
934adds very little overhead in itself. Like any select-based backend its 939same time). Nevertheless this shows that it adds very little overhead in
935performance becomes really bad with lots of file descriptors, of course, 940itself. Like any select-based backend its performance becomes really bad
941with lots of file descriptors (and few of them active), of course, but
936but this was not subject of this benchmark. 942this was not subject of this benchmark.
937 943
938The C<Event> module has a relatively high setup and callback invocation cost, 944The C<Event> module has a relatively high setup and callback invocation cost,
939but overall scores on the third place. 945but overall scores on the third place.
940 946
941C<Glib>'s memory usage is quite a bit bit higher, but it features a 947C<Glib>'s memory usage is quite a bit bit higher, but it features a

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