… | |
… | |
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 = '1.0'; |
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 |
387 | our $TEMPLATE; |
461 | our $TEMPLATE; |
|
|
462 | |
|
|
463 | sub QUEUE() { 0 } |
|
|
464 | sub FH() { 1 } |
|
|
465 | sub WW() { 2 } |
|
|
466 | sub PID() { 3 } |
|
|
467 | sub CB() { 4 } |
|
|
468 | |
|
|
469 | sub _new { |
|
|
470 | my ($self, $fh, $pid) = @_; |
|
|
471 | |
|
|
472 | AnyEvent::Util::fh_nonblocking $fh, 1; |
|
|
473 | |
|
|
474 | $self = bless [ |
|
|
475 | [], # write queue - strings or fd's |
|
|
476 | $fh, |
|
|
477 | undef, # AE watcher |
|
|
478 | $pid, |
|
|
479 | ], $self; |
|
|
480 | |
|
|
481 | $self |
|
|
482 | } |
388 | |
483 | |
389 | sub _cmd { |
484 | sub _cmd { |
390 | my $self = shift; |
485 | my $self = shift; |
391 | |
486 | |
392 | # ideally, we would want to use "a (w/a)*" as format string, but perl |
487 | # ideally, we would want to use "a (w/a)*" as format string, but perl |
393 | # versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack |
488 | # versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack |
394 | # it. |
489 | # it. |
395 | push @{ $self->[2] }, pack "a L/a*", $_[0], $_[1]; |
490 | push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1]; |
396 | |
491 | |
397 | $self->[3] ||= AE::io $self->[1], 1, sub { |
492 | $self->[WW] ||= AE::io $self->[FH], 1, sub { |
398 | do { |
493 | do { |
399 | # send the next "thing" in the queue - either a reference to an fh, |
494 | # send the next "thing" in the queue - either a reference to an fh, |
400 | # or a plain string. |
495 | # or a plain string. |
401 | |
496 | |
402 | if (ref $self->[2][0]) { |
497 | if (ref $self->[QUEUE][0]) { |
403 | # send fh |
498 | # send fh |
404 | unless (IO::FDPass::send fileno $self->[1], fileno ${ $self->[2][0] }) { |
499 | unless (IO::FDPass::send fileno $self->[FH], fileno ${ $self->[QUEUE][0] }) { |
405 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
500 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
406 | undef $self->[3]; |
501 | undef $self->[WW]; |
407 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
502 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
408 | } |
503 | } |
409 | |
504 | |
410 | shift @{ $self->[2] }; |
505 | shift @{ $self->[QUEUE] }; |
411 | |
506 | |
412 | } else { |
507 | } else { |
413 | # send string |
508 | # send string |
414 | my $len = syswrite $self->[1], $self->[2][0]; |
509 | my $len = syswrite $self->[FH], $self->[QUEUE][0]; |
415 | |
510 | |
416 | unless ($len) { |
511 | unless ($len) { |
417 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
512 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
418 | undef $self->[3]; |
513 | undef $self->[WW]; |
419 | die "AnyEvent::Fork: command write failure: $!"; |
514 | die "AnyEvent::Fork: command write failure: $!"; |
420 | } |
515 | } |
421 | |
516 | |
422 | substr $self->[2][0], 0, $len, ""; |
517 | substr $self->[QUEUE][0], 0, $len, ""; |
423 | shift @{ $self->[2] } unless length $self->[2][0]; |
518 | shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0]; |
424 | } |
519 | } |
425 | } while @{ $self->[2] }; |
520 | } while @{ $self->[QUEUE] }; |
426 | |
521 | |
427 | # everything written |
522 | # everything written |
428 | undef $self->[3]; |
523 | undef $self->[WW]; |
429 | |
524 | |
430 | # invoke run callback, if any |
525 | # invoke run callback, if any |
431 | $self->[4]->($self->[1]) if $self->[4]; |
526 | if ($self->[CB]) { |
|
|
527 | $self->[CB]->($self->[FH]); |
|
|
528 | @$self = (); |
|
|
529 | } |
432 | }; |
530 | }; |
433 | |
531 | |
434 | () # make sure we don't leak the watcher |
532 | () # make sure we don't leak the watcher |
435 | } |
|
|
436 | |
|
|
437 | sub _new { |
|
|
438 | my ($self, $fh, $pid) = @_; |
|
|
439 | |
|
|
440 | AnyEvent::Util::fh_nonblocking $fh, 1; |
|
|
441 | |
|
|
442 | $self = bless [ |
|
|
443 | $pid, |
|
|
444 | $fh, |
|
|
445 | [], # write queue - strings or fd's |
|
|
446 | undef, # AE watcher |
|
|
447 | ], $self; |
|
|
448 | |
|
|
449 | $self |
|
|
450 | } |
533 | } |
451 | |
534 | |
452 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
535 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
453 | sub _new_fork { |
536 | sub _new_fork { |
454 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
537 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
… | |
… | |
587 | AnyEvent::Fork itself. |
670 | AnyEvent::Fork itself. |
588 | |
671 | |
589 | =cut |
672 | =cut |
590 | |
673 | |
591 | sub pid { |
674 | sub pid { |
592 | $_[0][0] |
675 | $_[0][PID] |
593 | } |
676 | } |
594 | |
677 | |
595 | =item $proc = $proc->eval ($perlcode, @args) |
678 | =item $proc = $proc->eval ($perlcode, @args) |
596 | |
679 | |
597 | Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to |
680 | Evaluates the given C<$perlcode> as ... Perl code, while setting C<@_> to |
598 | the strings specified by C<@args>, in the "main" package. |
681 | the strings specified by C<@args>, in the "main" package. |
599 | |
682 | |
600 | This call is meant to do any custom initialisation that might be required |
683 | This call is meant to do any custom initialisation that might be required |
601 | (for example, the C<require> method uses it). It's not supposed to be used |
684 | (for example, the C<require> method uses it). It's not supposed to be used |
602 | to completely take over the process, use C<run> for that. |
685 | to completely take over the process, use C<run> for that. |
… | |
… | |
664 | sub send_fh { |
747 | sub send_fh { |
665 | my ($self, @fh) = @_; |
748 | my ($self, @fh) = @_; |
666 | |
749 | |
667 | for my $fh (@fh) { |
750 | for my $fh (@fh) { |
668 | $self->_cmd ("h"); |
751 | $self->_cmd ("h"); |
669 | push @{ $self->[2] }, \$fh; |
752 | push @{ $self->[QUEUE] }, \$fh; |
670 | } |
753 | } |
671 | |
754 | |
672 | $self |
755 | $self |
673 | } |
756 | } |
674 | |
757 | |
… | |
… | |
760 | =cut |
843 | =cut |
761 | |
844 | |
762 | sub run { |
845 | sub run { |
763 | my ($self, $func, $cb) = @_; |
846 | my ($self, $func, $cb) = @_; |
764 | |
847 | |
765 | $self->[4] = $cb; |
848 | $self->[CB] = $cb; |
766 | $self->_cmd (r => $func); |
849 | $self->_cmd (r => $func); |
|
|
850 | } |
|
|
851 | |
|
|
852 | =item $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
853 | |
|
|
854 | Flushes all commands out to the process and then calls the callback with |
|
|
855 | the communications socket. |
|
|
856 | |
|
|
857 | The process object becomes unusable on return from this function - any |
|
|
858 | further method calls result in undefined behaviour. |
|
|
859 | |
|
|
860 | The point of this method is to give you a file handle thta you cna pass |
|
|
861 | to another process. In that other process, you can call C<new_from_fh |
|
|
862 | AnyEvent::Fork> to create a new C<AnyEvent::Fork> object from it, thereby |
|
|
863 | effectively passing a fork object to another process. |
|
|
864 | |
|
|
865 | =cut |
|
|
866 | |
|
|
867 | sub to_fh { |
|
|
868 | my ($self, $cb) = @_; |
|
|
869 | |
|
|
870 | $self->[CB] = $cb; |
|
|
871 | |
|
|
872 | unless ($self->[WW]) { |
|
|
873 | $self->[CB]->($self->[FH]); |
|
|
874 | @$self = (); |
|
|
875 | } |
|
|
876 | } |
|
|
877 | |
|
|
878 | =item new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
879 | |
|
|
880 | Takes a file handle originally rceeived by the C<to_fh> method and creates |
|
|
881 | a new C<AnyEvent:Fork> object. The child process itself will not change in |
|
|
882 | any way, i.e. it will keep all the modifications done to it before calling |
|
|
883 | C<to_fh>. |
|
|
884 | |
|
|
885 | The new object is very much like the original object, except that the |
|
|
886 | C<pid> method will return C<undef> even if the process is a direct child. |
|
|
887 | |
|
|
888 | =cut |
|
|
889 | |
|
|
890 | sub new_from_fh { |
|
|
891 | my ($class, $fh) = @_; |
|
|
892 | |
|
|
893 | $class->_new ($fh) |
767 | } |
894 | } |
768 | |
895 | |
769 | =back |
896 | =back |
770 | |
897 | |
771 | =head1 PERFORMANCE |
898 | =head1 PERFORMANCE |
… | |
… | |
781 | |
908 | |
782 | 2079 new processes per second, using manual socketpair + fork |
909 | 2079 new processes per second, using manual socketpair + fork |
783 | |
910 | |
784 | Then I did the same thing, but instead of calling fork, I called |
911 | Then I did the same thing, but instead of calling fork, I called |
785 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
912 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
786 | socket form the child to close on exit. This does the same thing as manual |
913 | socket from the child to close on exit. This does the same thing as manual |
787 | socket pair + fork, except that what is forked is the template process |
914 | socket pair + fork, except that what is forked is the template process |
788 | (2440kB), and the socket needs to be passed to the server at the other end |
915 | (2440kB), and the socket needs to be passed to the server at the other end |
789 | of the socket first. |
916 | of the socket first. |
790 | |
917 | |
791 | 2307 new processes per second, using AnyEvent::Fork->new |
918 | 2307 new processes per second, using AnyEvent::Fork->new |
… | |
… | |
798 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
925 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
799 | though it uses the same operations, but adds a lot of overhead? |
926 | though it uses the same operations, but adds a lot of overhead? |
800 | |
927 | |
801 | The difference is simply the process size: forking the 5MB process takes |
928 | The difference is simply the process size: forking the 5MB process takes |
802 | so much longer than forking the 2.5MB template process that the extra |
929 | so much longer than forking the 2.5MB template process that the extra |
803 | overhead introduced is canceled out. |
930 | overhead is canceled out. |
804 | |
931 | |
805 | If the benchmark process grows, the normal fork becomes even slower: |
932 | If the benchmark process grows, the normal fork becomes even slower: |
806 | |
933 | |
807 | 1340 new processes, manual fork of a 20MB process |
934 | 1340 new processes, manual fork of a 20MB process |
808 | 731 new processes, manual fork of a 200MB process |
935 | 731 new processes, manual fork of a 200MB process |
… | |
… | |
868 | initialising them, for example, by calling C<init Gtk2> manually. |
995 | initialising them, for example, by calling C<init Gtk2> manually. |
869 | |
996 | |
870 | =item exiting calls object destructors |
997 | =item exiting calls object destructors |
871 | |
998 | |
872 | This only applies to users of L<AnyEvent::Fork:Early> and |
999 | This only applies to users of L<AnyEvent::Fork:Early> and |
873 | L<AnyEvent::Fork::Template>, or when initialiasing code creates objects |
1000 | L<AnyEvent::Fork::Template>, or when initialising code creates objects |
874 | that reference external resources. |
1001 | that reference external resources. |
875 | |
1002 | |
876 | When a process created by AnyEvent::Fork exits, it might do so by calling |
1003 | When a process created by AnyEvent::Fork exits, it might do so by calling |
877 | exit, or simply letting perl reach the end of the program. At which point |
1004 | exit, or simply letting perl reach the end of the program. At which point |
878 | Perl runs all destructors. |
1005 | Perl runs all destructors. |
… | |
… | |
898 | to make it so, mostly due to the bloody broken perl that nobody seems to |
1025 | to make it so, mostly due to the bloody broken perl that nobody seems to |
899 | care about. The fork emulation is a bad joke - I have yet to see something |
1026 | care about. The fork emulation is a bad joke - I have yet to see something |
900 | useful that you can do with it without running into memory corruption |
1027 | useful that you can do with it without running into memory corruption |
901 | issues or other braindamage. Hrrrr. |
1028 | issues or other braindamage. Hrrrr. |
902 | |
1029 | |
|
|
1030 | Since fork is endlessly broken on win32 perls (it doesn't even remotely |
|
|
1031 | work within it's documented limits) and quite obviously it's not getting |
|
|
1032 | improved any time soon, the best way to proceed on windows would be to |
|
|
1033 | always use C<new_exec> and thus never rely on perl's fork "emulation". |
|
|
1034 | |
903 | Cygwin perl is not supported at the moment due to some hilarious |
1035 | Cygwin perl is not supported at the moment due to some hilarious |
904 | shortcomings of its API - see L<IO::FDPoll> for more details. |
1036 | shortcomings of its API - see L<IO::FDPoll> for more details. If you never |
|
|
1037 | use C<send_fh> and always use C<new_exec> to create processes, it should |
|
|
1038 | work though. |
905 | |
1039 | |
906 | =head1 SEE ALSO |
1040 | =head1 SEE ALSO |
907 | |
1041 | |
908 | L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter), |
1042 | L<AnyEvent::Fork::Early>, to avoid executing a perl interpreter at all |
|
|
1043 | (part of this distribution). |
|
|
1044 | |
909 | L<AnyEvent::Fork::Template> (to create a process by forking the main |
1045 | L<AnyEvent::Fork::Template>, to create a process by forking the main |
910 | program at a convenient time). |
1046 | program at a convenient time (part of this distribution). |
911 | |
1047 | |
912 | =head1 AUTHOR |
1048 | L<AnyEvent::Fork::RPC>, for simple RPC to child processes (on CPAN). |
|
|
1049 | |
|
|
1050 | L<AnyEvent::Fork::Pool>, for simple worker process pool (on CPAN). |
|
|
1051 | |
|
|
1052 | =head1 AUTHOR AND CONTACT INFORMATION |
913 | |
1053 | |
914 | Marc Lehmann <schmorp@schmorp.de> |
1054 | Marc Lehmann <schmorp@schmorp.de> |
915 | http://home.schmorp.de/ |
1055 | http://software.schmorp.de/pkg/AnyEvent-Fork |
916 | |
1056 | |
917 | =cut |
1057 | =cut |
918 | |
1058 | |
919 | 1 |
1059 | 1 |
920 | |
1060 | |