… | |
… | |
34 | This module only creates processes and lets you pass file handles and |
34 | This module only creates processes and lets you pass file handles and |
35 | strings to it, and run perl code. It does not implement any kind of RPC - |
35 | strings to it, and run perl code. It does not implement any kind of RPC - |
36 | there is no back channel from the process back to you, and there is no RPC |
36 | there is no back channel from the process back to you, and there is no RPC |
37 | or message passing going on. |
37 | or message passing going on. |
38 | |
38 | |
39 | If you need some form of RPC, you can either implement it yourself |
39 | If you need some form of RPC, you could use the L<AnyEvent::Fork::RPC> |
40 | in whatever way you like, use some message-passing module such |
40 | companion module, which adds simple RPC/job queueing to a process created |
41 | as L<AnyEvent::MP>, some pipe such as L<AnyEvent::ZeroMQ>, use |
41 | by this module. |
42 | L<AnyEvent::Handle> on both sides to send e.g. JSON or Storable messages, |
42 | |
43 | and so on. |
43 | And if you need some automatic process pool management on top of |
|
|
44 | L<AnyEvent::Fork::RPC>, you can look at the L<AnyEvent::Fork::Pool> |
|
|
45 | companion module. |
|
|
46 | |
|
|
47 | Or you can implement it yourself in whatever way you like: use some |
|
|
48 | message-passing module such as L<AnyEvent::MP>, some pipe such as |
|
|
49 | L<AnyEvent::ZeroMQ>, use L<AnyEvent::Handle> on both sides to send |
|
|
50 | e.g. JSON or Storable messages, and so on. |
44 | |
51 | |
45 | =head2 COMPARISON TO OTHER MODULES |
52 | =head2 COMPARISON TO OTHER MODULES |
46 | |
53 | |
47 | There is an abundance of modules on CPAN that do "something fork", such as |
54 | There is an abundance of modules on CPAN that do "something fork", such as |
48 | L<Parallel::ForkManager>, L<AnyEvent::ForkManager>, L<AnyEvent::Worker> |
55 | L<Parallel::ForkManager>, L<AnyEvent::ForkManager>, L<AnyEvent::Worker> |
… | |
… | |
221 | } |
228 | } |
222 | } |
229 | } |
223 | |
230 | |
224 | =head2 use AnyEvent::Fork as a faster fork+exec |
231 | =head2 use AnyEvent::Fork as a faster fork+exec |
225 | |
232 | |
226 | This runs C</bin/echo hi>, with stdandard output redirected to /tmp/log |
233 | This runs C</bin/echo hi>, with standard output redirected to F</tmp/log> |
227 | and standard error redirected to the communications socket. It is usually |
234 | and standard error redirected to the communications socket. It is usually |
228 | faster than fork+exec, but still lets you prepare the environment. |
235 | faster than fork+exec, but still lets you prepare the environment. |
229 | |
236 | |
230 | open my $output, ">/tmp/log" or die "$!"; |
237 | open my $output, ">/tmp/log" or die "$!"; |
231 | |
238 | |
… | |
… | |
247 | ->send_arg ("/bin/echo", "hi") |
254 | ->send_arg ("/bin/echo", "hi") |
248 | ->run ("run", my $cv = AE::cv); |
255 | ->run ("run", my $cv = AE::cv); |
249 | |
256 | |
250 | my $stderr = $cv->recv; |
257 | my $stderr = $cv->recv; |
251 | |
258 | |
|
|
259 | =head2 For stingy users: put the worker code into a C<DATA> section. |
|
|
260 | |
|
|
261 | When you want to be stingy with files, you cna put your code into the |
|
|
262 | C<DATA> section of your module (or program): |
|
|
263 | |
|
|
264 | use AnyEvent::Fork; |
|
|
265 | |
|
|
266 | AnyEvent::Fork |
|
|
267 | ->new |
|
|
268 | ->eval (do { local $/; <DATA> }) |
|
|
269 | ->run ("doit", sub { ... }); |
|
|
270 | |
|
|
271 | __DATA__ |
|
|
272 | |
|
|
273 | sub doit { |
|
|
274 | ... do something! |
|
|
275 | } |
|
|
276 | |
|
|
277 | =head2 For stingy standalone programs: do not rely on external files at |
|
|
278 | all. |
|
|
279 | |
|
|
280 | For single-file scripts it can be inconvenient to rely on external |
|
|
281 | files - even when using < C<DATA> section, you still need to C<exec> |
|
|
282 | an external perl interpreter, which might not be available when using |
|
|
283 | L<App::Staticperl>, L<Urlader> or L<PAR::Packer> for example. |
|
|
284 | |
|
|
285 | Two modules help here - L<AnyEvent::Fork::Early> forks a template process |
|
|
286 | for all further calls to C<new_exec>, and L<AnyEvent::Fork::Template> |
|
|
287 | forks the main program as a template process. |
|
|
288 | |
|
|
289 | Here is how your main program should look like: |
|
|
290 | |
|
|
291 | #! perl |
|
|
292 | |
|
|
293 | # optional, as the very first thing. |
|
|
294 | # in case modules want to create their own processes. |
|
|
295 | use AnyEvent::Fork::Early; |
|
|
296 | |
|
|
297 | # next, load all modules you need in your template process |
|
|
298 | use Example::My::Module |
|
|
299 | use Example::Whatever; |
|
|
300 | |
|
|
301 | # next, put your run function definition and anything else you |
|
|
302 | # need, but do not use code outside of BEGIN blocks. |
|
|
303 | sub worker_run { |
|
|
304 | my ($fh, @args) = @_; |
|
|
305 | ... |
|
|
306 | } |
|
|
307 | |
|
|
308 | # now preserve everything so far as AnyEvent::Fork object |
|
|
309 | # in §TEMPLATE. |
|
|
310 | use AnyEvent::Fork::Template; |
|
|
311 | |
|
|
312 | # do not put code outside of BEGIN blocks until here |
|
|
313 | |
|
|
314 | # now use the $TEMPLATE process in any way you like |
|
|
315 | |
|
|
316 | # for example: create 10 worker processes |
|
|
317 | my @worker; |
|
|
318 | my $cv = AE::cv; |
|
|
319 | for (1..10) { |
|
|
320 | $cv->begin; |
|
|
321 | $TEMPLATE->fork->send_arg ($_)->run ("worker_run", sub { |
|
|
322 | push @worker, shift; |
|
|
323 | $cv->end; |
|
|
324 | }); |
|
|
325 | } |
|
|
326 | $cv->recv; |
|
|
327 | |
252 | =head1 CONCEPTS |
328 | =head1 CONCEPTS |
253 | |
329 | |
254 | This module can create new processes either by executing a new perl |
330 | This module can create new processes either by executing a new perl |
255 | process, or by forking from an existing "template" process. |
331 | process, or by forking from an existing "template" process. |
|
|
332 | |
|
|
333 | All these processes are called "child processes" (whether they are direct |
|
|
334 | children or not), while the process that manages them is called the |
|
|
335 | "parent process". |
256 | |
336 | |
257 | Each such process comes with its own file handle that can be used to |
337 | Each such process comes with its own file handle that can be used to |
258 | communicate with it (it's actually a socket - one end in the new process, |
338 | communicate with it (it's actually a socket - one end in the new process, |
259 | one end in the main process), and among the things you can do in it are |
339 | one end in the main process), and among the things you can do in it are |
260 | load modules, fork new processes, send file handles to it, and execute |
340 | load modules, fork new processes, send file handles to it, and execute |
… | |
… | |
370 | use AnyEvent; |
450 | use AnyEvent; |
371 | use AnyEvent::Util (); |
451 | use AnyEvent::Util (); |
372 | |
452 | |
373 | use IO::FDPass; |
453 | use IO::FDPass; |
374 | |
454 | |
375 | our $VERSION = 0.6; |
455 | our $VERSION = 1.1; |
376 | |
|
|
377 | =over 4 |
|
|
378 | |
|
|
379 | =back |
|
|
380 | |
|
|
381 | =cut |
|
|
382 | |
456 | |
383 | # the early fork template process |
457 | # the early fork template process |
384 | our $EARLY; |
458 | our $EARLY; |
385 | |
459 | |
386 | # the empty template process |
460 | # the empty template process |
… | |
… | |
434 | # send string |
508 | # send string |
435 | my $len = syswrite $self->[FH], $self->[QUEUE][0]; |
509 | my $len = syswrite $self->[FH], $self->[QUEUE][0]; |
436 | |
510 | |
437 | unless ($len) { |
511 | unless ($len) { |
438 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
512 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
439 | undef $self->[3]; |
513 | undef $self->[WW]; |
440 | die "AnyEvent::Fork: command write failure: $!"; |
514 | die "AnyEvent::Fork: command write failure: $!"; |
441 | } |
515 | } |
442 | |
516 | |
443 | substr $self->[QUEUE][0], 0, $len, ""; |
517 | substr $self->[QUEUE][0], 0, $len, ""; |
444 | shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0]; |
518 | shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0]; |
… | |
… | |
447 | |
521 | |
448 | # everything written |
522 | # everything written |
449 | undef $self->[WW]; |
523 | undef $self->[WW]; |
450 | |
524 | |
451 | # invoke run callback, if any |
525 | # invoke run callback, if any |
|
|
526 | if ($self->[CB]) { |
452 | $self->[CB]->($self->[FH]) if $self->[CB]; |
527 | $self->[CB]->($self->[FH]); |
|
|
528 | @$self = (); |
|
|
529 | } |
453 | }; |
530 | }; |
454 | |
531 | |
455 | () # make sure we don't leak the watcher |
532 | () # make sure we don't leak the watcher |
456 | } |
533 | } |
457 | |
534 | |
… | |
… | |
532 | The path to the perl interpreter is divined using various methods - first |
609 | The path to the perl interpreter is divined using various methods - first |
533 | C<$^X> is investigated to see if the path ends with something that sounds |
610 | C<$^X> is investigated to see if the path ends with something that sounds |
534 | as if it were the perl interpreter. Failing this, the module falls back to |
611 | as if it were the perl interpreter. Failing this, the module falls back to |
535 | using C<$Config::Config{perlpath}>. |
612 | using C<$Config::Config{perlpath}>. |
536 | |
613 | |
|
|
614 | The path to perl can also be overriden by setting the global variable |
|
|
615 | C<$AnyEvent::Fork::PERL> - it's value will be used for all subsequent |
|
|
616 | invocations. |
|
|
617 | |
537 | =cut |
618 | =cut |
|
|
619 | |
|
|
620 | our $PERL; |
538 | |
621 | |
539 | sub new_exec { |
622 | sub new_exec { |
540 | my ($self) = @_; |
623 | my ($self) = @_; |
541 | |
624 | |
542 | return $EARLY->fork |
625 | return $EARLY->fork |
543 | if $EARLY; |
626 | if $EARLY; |
544 | |
627 | |
|
|
628 | unless (defined $PERL) { |
545 | # first find path of perl |
629 | # first find path of perl |
546 | my $perl = $; |
630 | my $perl = $; |
547 | |
631 | |
548 | # first we try $^X, but the path must be absolute (always on win32), and end in sth. |
632 | # first we try $^X, but the path must be absolute (always on win32), and end in sth. |
549 | # that looks like perl. this obviously only works for posix and win32 |
633 | # that looks like perl. this obviously only works for posix and win32 |
550 | unless ( |
634 | unless ( |
551 | ($^O eq "MSWin32" || $perl =~ m%^/%) |
635 | ($^O eq "MSWin32" || $perl =~ m%^/%) |
552 | && $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i |
636 | && $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i |
553 | ) { |
637 | ) { |
554 | # if it doesn't look perlish enough, try Config |
638 | # if it doesn't look perlish enough, try Config |
555 | require Config; |
639 | require Config; |
556 | $perl = $Config::Config{perlpath}; |
640 | $perl = $Config::Config{perlpath}; |
557 | $perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/; |
641 | $perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/; |
|
|
642 | } |
|
|
643 | |
|
|
644 | $PERL = $perl; |
558 | } |
645 | } |
559 | |
646 | |
560 | require Proc::FastSpawn; |
647 | require Proc::FastSpawn; |
561 | |
648 | |
562 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
649 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
… | |
… | |
570 | #local $ENV{PERL5LIB} = join ":", grep !ref, @INC; |
657 | #local $ENV{PERL5LIB} = join ":", grep !ref, @INC; |
571 | my %env = %ENV; |
658 | my %env = %ENV; |
572 | $env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC; |
659 | $env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC; |
573 | |
660 | |
574 | my $pid = Proc::FastSpawn::spawn ( |
661 | my $pid = Proc::FastSpawn::spawn ( |
575 | $perl, |
662 | $PERL, |
576 | ["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$], |
663 | ["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$], |
577 | [map "$_=$env{$_}", keys %env], |
664 | [map "$_=$env{$_}", keys %env], |
578 | ) or die "unable to spawn AnyEvent::Fork server: $!"; |
665 | ) or die "unable to spawn AnyEvent::Fork server: $!"; |
579 | |
666 | |
580 | $self->_new ($fh, $pid) |
667 | $self->_new ($fh, $pid) |
… | |
… | |
598 | $_[0][PID] |
685 | $_[0][PID] |
599 | } |
686 | } |
600 | |
687 | |
601 | =item $proc = $proc->eval ($perlcode, @args) |
688 | =item $proc = $proc->eval ($perlcode, @args) |
602 | |
689 | |
603 | Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to |
690 | Evaluates the given C<$perlcode> as ... Perl code, while setting C<@_> to |
604 | the strings specified by C<@args>, in the "main" package. |
691 | the strings specified by C<@args>, in the "main" package. |
605 | |
692 | |
606 | This call is meant to do any custom initialisation that might be required |
693 | This call is meant to do any custom initialisation that might be required |
607 | (for example, the C<require> method uses it). It's not supposed to be used |
694 | (for example, the C<require> method uses it). It's not supposed to be used |
608 | to completely take over the process, use C<run> for that. |
695 | to completely take over the process, use C<run> for that. |
… | |
… | |
772 | $self->_cmd (r => $func); |
859 | $self->_cmd (r => $func); |
773 | } |
860 | } |
774 | |
861 | |
775 | =back |
862 | =back |
776 | |
863 | |
|
|
864 | =head2 EXPERIMENTAL METHODS |
|
|
865 | |
|
|
866 | These methods might go away completely or change behaviour, at any time. |
|
|
867 | |
|
|
868 | =over 4 |
|
|
869 | |
|
|
870 | =item $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
871 | |
|
|
872 | Flushes all commands out to the process and then calls the callback with |
|
|
873 | the communications socket. |
|
|
874 | |
|
|
875 | The process object becomes unusable on return from this function - any |
|
|
876 | further method calls result in undefined behaviour. |
|
|
877 | |
|
|
878 | The point of this method is to give you a file handle thta you cna pass |
|
|
879 | to another process. In that other process, you can call C<new_from_fh |
|
|
880 | AnyEvent::Fork> to create a new C<AnyEvent::Fork> object from it, thereby |
|
|
881 | effectively passing a fork object to another process. |
|
|
882 | |
|
|
883 | =cut |
|
|
884 | |
|
|
885 | sub to_fh { |
|
|
886 | my ($self, $cb) = @_; |
|
|
887 | |
|
|
888 | $self->[CB] = $cb; |
|
|
889 | |
|
|
890 | unless ($self->[WW]) { |
|
|
891 | $self->[CB]->($self->[FH]); |
|
|
892 | @$self = (); |
|
|
893 | } |
|
|
894 | } |
|
|
895 | |
|
|
896 | =item new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
897 | |
|
|
898 | Takes a file handle originally rceeived by the C<to_fh> method and creates |
|
|
899 | a new C<AnyEvent:Fork> object. The child process itself will not change in |
|
|
900 | any way, i.e. it will keep all the modifications done to it before calling |
|
|
901 | C<to_fh>. |
|
|
902 | |
|
|
903 | The new object is very much like the original object, except that the |
|
|
904 | C<pid> method will return C<undef> even if the process is a direct child. |
|
|
905 | |
|
|
906 | =cut |
|
|
907 | |
|
|
908 | sub new_from_fh { |
|
|
909 | my ($class, $fh) = @_; |
|
|
910 | |
|
|
911 | $class->_new ($fh) |
|
|
912 | } |
|
|
913 | |
|
|
914 | =back |
|
|
915 | |
777 | =head1 PERFORMANCE |
916 | =head1 PERFORMANCE |
778 | |
917 | |
779 | Now for some unscientific benchmark numbers (all done on an amd64 |
918 | Now for some unscientific benchmark numbers (all done on an amd64 |
780 | GNU/Linux box). These are intended to give you an idea of the relative |
919 | GNU/Linux box). These are intended to give you an idea of the relative |
781 | performance you can expect, they are not meant to be absolute performance |
920 | performance you can expect, they are not meant to be absolute performance |
… | |
… | |
787 | |
926 | |
788 | 2079 new processes per second, using manual socketpair + fork |
927 | 2079 new processes per second, using manual socketpair + fork |
789 | |
928 | |
790 | Then I did the same thing, but instead of calling fork, I called |
929 | Then I did the same thing, but instead of calling fork, I called |
791 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
930 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
792 | socket form the child to close on exit. This does the same thing as manual |
931 | socket from the child to close on exit. This does the same thing as manual |
793 | socket pair + fork, except that what is forked is the template process |
932 | socket pair + fork, except that what is forked is the template process |
794 | (2440kB), and the socket needs to be passed to the server at the other end |
933 | (2440kB), and the socket needs to be passed to the server at the other end |
795 | of the socket first. |
934 | of the socket first. |
796 | |
935 | |
797 | 2307 new processes per second, using AnyEvent::Fork->new |
936 | 2307 new processes per second, using AnyEvent::Fork->new |
… | |
… | |
804 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
943 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
805 | though it uses the same operations, but adds a lot of overhead? |
944 | though it uses the same operations, but adds a lot of overhead? |
806 | |
945 | |
807 | The difference is simply the process size: forking the 5MB process takes |
946 | The difference is simply the process size: forking the 5MB process takes |
808 | so much longer than forking the 2.5MB template process that the extra |
947 | so much longer than forking the 2.5MB template process that the extra |
809 | overhead introduced is canceled out. |
948 | overhead is canceled out. |
810 | |
949 | |
811 | If the benchmark process grows, the normal fork becomes even slower: |
950 | If the benchmark process grows, the normal fork becomes even slower: |
812 | |
951 | |
813 | 1340 new processes, manual fork of a 20MB process |
952 | 1340 new processes, manual fork of a 20MB process |
814 | 731 new processes, manual fork of a 200MB process |
953 | 731 new processes, manual fork of a 200MB process |
… | |
… | |
874 | initialising them, for example, by calling C<init Gtk2> manually. |
1013 | initialising them, for example, by calling C<init Gtk2> manually. |
875 | |
1014 | |
876 | =item exiting calls object destructors |
1015 | =item exiting calls object destructors |
877 | |
1016 | |
878 | This only applies to users of L<AnyEvent::Fork:Early> and |
1017 | This only applies to users of L<AnyEvent::Fork:Early> and |
879 | L<AnyEvent::Fork::Template>, or when initialiasing code creates objects |
1018 | L<AnyEvent::Fork::Template>, or when initialising code creates objects |
880 | that reference external resources. |
1019 | that reference external resources. |
881 | |
1020 | |
882 | When a process created by AnyEvent::Fork exits, it might do so by calling |
1021 | When a process created by AnyEvent::Fork exits, it might do so by calling |
883 | exit, or simply letting perl reach the end of the program. At which point |
1022 | exit, or simply letting perl reach the end of the program. At which point |
884 | Perl runs all destructors. |
1023 | Perl runs all destructors. |
… | |
… | |
904 | to make it so, mostly due to the bloody broken perl that nobody seems to |
1043 | to make it so, mostly due to the bloody broken perl that nobody seems to |
905 | care about. The fork emulation is a bad joke - I have yet to see something |
1044 | care about. The fork emulation is a bad joke - I have yet to see something |
906 | useful that you can do with it without running into memory corruption |
1045 | useful that you can do with it without running into memory corruption |
907 | issues or other braindamage. Hrrrr. |
1046 | issues or other braindamage. Hrrrr. |
908 | |
1047 | |
|
|
1048 | Since fork is endlessly broken on win32 perls (it doesn't even remotely |
|
|
1049 | work within it's documented limits) and quite obviously it's not getting |
|
|
1050 | improved any time soon, the best way to proceed on windows would be to |
|
|
1051 | always use C<new_exec> and thus never rely on perl's fork "emulation". |
|
|
1052 | |
909 | Cygwin perl is not supported at the moment due to some hilarious |
1053 | Cygwin perl is not supported at the moment due to some hilarious |
910 | shortcomings of its API - see L<IO::FDPoll> for more details. |
1054 | shortcomings of its API - see L<IO::FDPoll> for more details. If you never |
|
|
1055 | use C<send_fh> and always use C<new_exec> to create processes, it should |
|
|
1056 | work though. |
911 | |
1057 | |
912 | =head1 SEE ALSO |
1058 | =head1 SEE ALSO |
913 | |
1059 | |
914 | L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter), |
1060 | L<AnyEvent::Fork::Early>, to avoid executing a perl interpreter at all |
|
|
1061 | (part of this distribution). |
|
|
1062 | |
915 | L<AnyEvent::Fork::Template> (to create a process by forking the main |
1063 | L<AnyEvent::Fork::Template>, to create a process by forking the main |
916 | program at a convenient time). |
1064 | program at a convenient time (part of this distribution). |
917 | |
1065 | |
918 | =head1 AUTHOR |
1066 | L<AnyEvent::Fork::RPC>, for simple RPC to child processes (on CPAN). |
|
|
1067 | |
|
|
1068 | L<AnyEvent::Fork::Pool>, for simple worker process pool (on CPAN). |
|
|
1069 | |
|
|
1070 | =head1 AUTHOR AND CONTACT INFORMATION |
919 | |
1071 | |
920 | Marc Lehmann <schmorp@schmorp.de> |
1072 | Marc Lehmann <schmorp@schmorp.de> |
921 | http://home.schmorp.de/ |
1073 | http://software.schmorp.de/pkg/AnyEvent-Fork |
922 | |
1074 | |
923 | =cut |
1075 | =cut |
924 | |
1076 | |
925 | 1 |
1077 | 1 |
926 | |
1078 | |