… | |
… | |
27 | |
27 | |
28 | Special care has been taken to make this module useful from other modules, |
28 | Special care has been taken to make this module useful from other modules, |
29 | while still supporting specialised environments such as L<App::Staticperl> |
29 | while still supporting specialised environments such as L<App::Staticperl> |
30 | or L<PAR::Packer>. |
30 | or L<PAR::Packer>. |
31 | |
31 | |
32 | =head1 WHAT THIS MODULE IS NOT |
32 | =head2 WHAT THIS MODULE IS NOT |
33 | |
33 | |
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, |
|
|
43 | and so on. |
|
|
44 | |
42 | |
|
|
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. |
|
|
51 | |
|
|
52 | =head2 COMPARISON TO OTHER MODULES |
|
|
53 | |
|
|
54 | There is an abundance of modules on CPAN that do "something fork", such as |
|
|
55 | L<Parallel::ForkManager>, L<AnyEvent::ForkManager>, L<AnyEvent::Worker> |
|
|
56 | or L<AnyEvent::Subprocess>. There are modules that implement their own |
|
|
57 | process management, such as L<AnyEvent::DBI>. |
|
|
58 | |
|
|
59 | The problems that all these modules try to solve are real, however, none |
|
|
60 | of them (from what I have seen) tackle the very real problems of unwanted |
|
|
61 | memory sharing, efficiency, not being able to use event processing or |
|
|
62 | similar modules in the processes they create. |
|
|
63 | |
|
|
64 | This module doesn't try to replace any of them - instead it tries to solve |
|
|
65 | the problem of creating processes with a minimum of fuss and overhead (and |
|
|
66 | also luxury). Ideally, most of these would use AnyEvent::Fork internally, |
|
|
67 | except they were written before AnyEvent:Fork was available, so obviously |
|
|
68 | had to roll their own. |
|
|
69 | |
45 | =head1 PROBLEM STATEMENT |
70 | =head2 PROBLEM STATEMENT |
46 | |
71 | |
47 | There are two traditional ways to implement parallel processing on UNIX |
72 | There are two traditional ways to implement parallel processing on UNIX |
48 | like operating systems - fork and process, and fork+exec and process. They |
73 | like operating systems - fork and process, and fork+exec and process. They |
49 | have different advantages and disadvantages that I describe below, |
74 | have different advantages and disadvantages that I describe below, |
50 | together with how this module tries to mitigate the disadvantages. |
75 | together with how this module tries to mitigate the disadvantages. |
… | |
… | |
203 | } |
228 | } |
204 | } |
229 | } |
205 | |
230 | |
206 | =head2 use AnyEvent::Fork as a faster fork+exec |
231 | =head2 use AnyEvent::Fork as a faster fork+exec |
207 | |
232 | |
208 | 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> |
209 | and standard error redirected to the communications socket. It is usually |
234 | and standard error redirected to the communications socket. It is usually |
210 | faster than fork+exec, but still lets you prepare the environment. |
235 | faster than fork+exec, but still lets you prepare the environment. |
211 | |
236 | |
212 | open my $output, ">/tmp/log" or die "$!"; |
237 | open my $output, ">/tmp/log" or die "$!"; |
213 | |
238 | |
214 | AnyEvent::Fork |
239 | AnyEvent::Fork |
215 | ->new |
240 | ->new |
216 | ->eval (' |
241 | ->eval (' |
|
|
242 | # compile a helper function for later use |
217 | sub run { |
243 | sub run { |
218 | my ($fh, $output, @cmd) = @_; |
244 | my ($fh, $output, @cmd) = @_; |
219 | |
245 | |
220 | # perl will clear close-on-exec on STDOUT/STDERR |
246 | # perl will clear close-on-exec on STDOUT/STDERR |
221 | open STDOUT, ">&", $output or die; |
247 | open STDOUT, ">&", $output or die; |
… | |
… | |
228 | ->send_arg ("/bin/echo", "hi") |
254 | ->send_arg ("/bin/echo", "hi") |
229 | ->run ("run", my $cv = AE::cv); |
255 | ->run ("run", my $cv = AE::cv); |
230 | |
256 | |
231 | my $stderr = $cv->recv; |
257 | my $stderr = $cv->recv; |
232 | |
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 | |
233 | =head1 CONCEPTS |
328 | =head1 CONCEPTS |
234 | |
329 | |
235 | 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 |
236 | 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". |
237 | |
336 | |
238 | 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 |
239 | 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, |
240 | 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 |
241 | 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 |
… | |
… | |
351 | use AnyEvent; |
450 | use AnyEvent; |
352 | use AnyEvent::Util (); |
451 | use AnyEvent::Util (); |
353 | |
452 | |
354 | use IO::FDPass; |
453 | use IO::FDPass; |
355 | |
454 | |
356 | our $VERSION = 0.5; |
455 | our $VERSION = '1.0'; |
357 | |
|
|
358 | our $PERL; # the path to the perl interpreter, deduces with various forms of magic |
|
|
359 | |
|
|
360 | =over 4 |
|
|
361 | |
|
|
362 | =back |
|
|
363 | |
|
|
364 | =cut |
|
|
365 | |
456 | |
366 | # the early fork template process |
457 | # the early fork template process |
367 | our $EARLY; |
458 | our $EARLY; |
368 | |
459 | |
369 | # the empty template process |
460 | # the empty template process |
370 | 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 | } |
371 | |
483 | |
372 | sub _cmd { |
484 | sub _cmd { |
373 | my $self = shift; |
485 | my $self = shift; |
374 | |
486 | |
375 | # 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 |
376 | # 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 |
377 | # it. |
489 | # it. |
378 | push @{ $self->[2] }, pack "a L/a*", $_[0], $_[1]; |
490 | push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1]; |
379 | |
491 | |
380 | $self->[3] ||= AE::io $self->[1], 1, sub { |
492 | $self->[WW] ||= AE::io $self->[FH], 1, sub { |
381 | do { |
493 | do { |
382 | # 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, |
383 | # or a plain string. |
495 | # or a plain string. |
384 | |
496 | |
385 | if (ref $self->[2][0]) { |
497 | if (ref $self->[QUEUE][0]) { |
386 | # send fh |
498 | # send fh |
387 | unless (IO::FDPass::send fileno $self->[1], fileno ${ $self->[2][0] }) { |
499 | unless (IO::FDPass::send fileno $self->[FH], fileno ${ $self->[QUEUE][0] }) { |
388 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
500 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
389 | undef $self->[3]; |
501 | undef $self->[WW]; |
390 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
502 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
391 | } |
503 | } |
392 | |
504 | |
393 | shift @{ $self->[2] }; |
505 | shift @{ $self->[QUEUE] }; |
394 | |
506 | |
395 | } else { |
507 | } else { |
396 | # send string |
508 | # send string |
397 | my $len = syswrite $self->[1], $self->[2][0]; |
509 | my $len = syswrite $self->[FH], $self->[QUEUE][0]; |
398 | |
510 | |
399 | unless ($len) { |
511 | unless ($len) { |
400 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
512 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
401 | undef $self->[3]; |
513 | undef $self->[WW]; |
402 | die "AnyEvent::Fork: command write failure: $!"; |
514 | die "AnyEvent::Fork: command write failure: $!"; |
403 | } |
515 | } |
404 | |
516 | |
405 | substr $self->[2][0], 0, $len, ""; |
517 | substr $self->[QUEUE][0], 0, $len, ""; |
406 | shift @{ $self->[2] } unless length $self->[2][0]; |
518 | shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0]; |
407 | } |
519 | } |
408 | } while @{ $self->[2] }; |
520 | } while @{ $self->[QUEUE] }; |
409 | |
521 | |
410 | # everything written |
522 | # everything written |
411 | undef $self->[3]; |
523 | undef $self->[WW]; |
412 | |
524 | |
413 | # invoke run callback, if any |
525 | # invoke run callback, if any |
414 | $self->[4]->($self->[1]) if $self->[4]; |
526 | if ($self->[CB]) { |
|
|
527 | $self->[CB]->($self->[FH]); |
|
|
528 | @$self = (); |
|
|
529 | } |
415 | }; |
530 | }; |
416 | |
531 | |
417 | () # make sure we don't leak the watcher |
532 | () # make sure we don't leak the watcher |
418 | } |
|
|
419 | |
|
|
420 | sub _new { |
|
|
421 | my ($self, $fh, $pid) = @_; |
|
|
422 | |
|
|
423 | AnyEvent::Util::fh_nonblocking $fh, 1; |
|
|
424 | |
|
|
425 | $self = bless [ |
|
|
426 | $pid, |
|
|
427 | $fh, |
|
|
428 | [], # write queue - strings or fd's |
|
|
429 | undef, # AE watcher |
|
|
430 | ], $self; |
|
|
431 | |
|
|
432 | $self |
|
|
433 | } |
533 | } |
434 | |
534 | |
435 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
535 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
436 | sub _new_fork { |
536 | sub _new_fork { |
437 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
537 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
… | |
… | |
442 | if ($pid eq 0) { |
542 | if ($pid eq 0) { |
443 | require AnyEvent::Fork::Serve; |
543 | require AnyEvent::Fork::Serve; |
444 | $AnyEvent::Fork::Serve::OWNER = $parent; |
544 | $AnyEvent::Fork::Serve::OWNER = $parent; |
445 | close $fh; |
545 | close $fh; |
446 | $0 = "$_[1] of $parent"; |
546 | $0 = "$_[1] of $parent"; |
447 | $SIG{CHLD} = 'IGNORE'; |
|
|
448 | AnyEvent::Fork::Serve::serve ($slave); |
547 | AnyEvent::Fork::Serve::serve ($slave); |
449 | exit 0; |
548 | exit 0; |
450 | } elsif (!$pid) { |
549 | } elsif (!$pid) { |
451 | die "AnyEvent::Fork::Early/Template: unable to fork template process: $!"; |
550 | die "AnyEvent::Fork::Early/Template: unable to fork template process: $!"; |
452 | } |
551 | } |
… | |
… | |
571 | AnyEvent::Fork itself. |
670 | AnyEvent::Fork itself. |
572 | |
671 | |
573 | =cut |
672 | =cut |
574 | |
673 | |
575 | sub pid { |
674 | sub pid { |
576 | $_[0][0] |
675 | $_[0][PID] |
577 | } |
676 | } |
578 | |
677 | |
579 | =item $proc = $proc->eval ($perlcode, @args) |
678 | =item $proc = $proc->eval ($perlcode, @args) |
580 | |
679 | |
581 | 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 |
582 | the strings specified by C<@args>, in the "main" package. |
681 | the strings specified by C<@args>, in the "main" package. |
583 | |
682 | |
584 | 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 |
585 | (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 |
586 | to completely take over the process, use C<run> for that. |
685 | to completely take over the process, use C<run> for that. |
… | |
… | |
648 | sub send_fh { |
747 | sub send_fh { |
649 | my ($self, @fh) = @_; |
748 | my ($self, @fh) = @_; |
650 | |
749 | |
651 | for my $fh (@fh) { |
750 | for my $fh (@fh) { |
652 | $self->_cmd ("h"); |
751 | $self->_cmd ("h"); |
653 | push @{ $self->[2] }, \$fh; |
752 | push @{ $self->[QUEUE] }, \$fh; |
654 | } |
753 | } |
655 | |
754 | |
656 | $self |
755 | $self |
657 | } |
756 | } |
658 | |
757 | |
… | |
… | |
744 | =cut |
843 | =cut |
745 | |
844 | |
746 | sub run { |
845 | sub run { |
747 | my ($self, $func, $cb) = @_; |
846 | my ($self, $func, $cb) = @_; |
748 | |
847 | |
749 | $self->[4] = $cb; |
848 | $self->[CB] = $cb; |
750 | $self->_cmd (r => $func); |
849 | $self->_cmd (r => $func); |
|
|
850 | } |
|
|
851 | |
|
|
852 | =back |
|
|
853 | |
|
|
854 | =head2 ADVANCED METHODS |
|
|
855 | |
|
|
856 | =over 4 |
|
|
857 | |
|
|
858 | =item new_from_stdio AnyEvent::Fork $fh |
|
|
859 | |
|
|
860 | Assume that you have a perl interpreter running (without any special |
|
|
861 | options or a program) somewhere and it has it's STDIN and STDOUT connected |
|
|
862 | to the C<$fh> somehow. I.e. exactly the state perl is in when you start it |
|
|
863 | without any arguments: |
|
|
864 | |
|
|
865 | perl |
|
|
866 | |
|
|
867 | Then you can create an C<AnyEvent::Fork> object out of this perl |
|
|
868 | interpreter with this constructor. |
|
|
869 | |
|
|
870 | When the usefulness of this isn't immediately clear, imagine you manage to |
|
|
871 | run a perl interpreter remotely (F<ssh remotemachine perl>), then you can |
|
|
872 | manage it mostly like a local C<AnyEvent::Fork> child. |
|
|
873 | |
|
|
874 | This works without any module support, i.e. the remote F<perl> does not |
|
|
875 | need to have any special modules installed. |
|
|
876 | |
|
|
877 | There are a number of limitations though: C<send_fh> will only work if the |
|
|
878 | L<IO::FDPass> module is loadable by the remote perl and the two processes |
|
|
879 | are connected in a way that let's L<IO::FDPass> do it's work. |
|
|
880 | |
|
|
881 | This will therefore not work over a network conenction. From this follows |
|
|
882 | that C<fork> will also not work under these circumstances, as it relies on |
|
|
883 | C<send_fh> internally. |
|
|
884 | |
|
|
885 | =cut |
|
|
886 | |
|
|
887 | sub new_from_stdio { |
|
|
888 | my ($class, $fh) = @_; |
|
|
889 | |
|
|
890 | my $self = $class->_new ($fh); |
|
|
891 | |
|
|
892 | # send startup code |
|
|
893 | push @{ $self->[QUEUE] }, |
|
|
894 | (do "AnyEvent/Fork/serve.pl") |
|
|
895 | . <<'EOF'; |
|
|
896 | { |
|
|
897 | open my $fh, "+<&0" |
|
|
898 | or die "AnyEvent::Fork::Serve::stdio: unable to open communications socket: $!\n"; |
|
|
899 | open STDIN , ">&2"; |
|
|
900 | open STDOUT, ">&2"; |
|
|
901 | |
|
|
902 | $OWNER = "another process"; |
|
|
903 | $0 = "AnyEvent::Fork/stdio of $OWNER"; |
|
|
904 | |
|
|
905 | @_ = $fh; |
|
|
906 | } |
|
|
907 | |
|
|
908 | &serve; |
|
|
909 | __END__ |
|
|
910 | EOF |
|
|
911 | |
|
|
912 | # the data is only sent when the user requests additional things, which |
|
|
913 | # is likely early enough for our purposes. |
|
|
914 | |
|
|
915 | $self |
|
|
916 | } |
|
|
917 | |
|
|
918 | =back |
|
|
919 | |
|
|
920 | =head2 EXPERIMENTAL METHODS |
|
|
921 | |
|
|
922 | These methods might go away completely or change behaviour, a any time. |
|
|
923 | |
|
|
924 | =over 4 |
|
|
925 | |
|
|
926 | =item $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
927 | |
|
|
928 | Flushes all commands out to the process and then calls the callback with |
|
|
929 | the communications socket. |
|
|
930 | |
|
|
931 | The process object becomes unusable on return from this function - any |
|
|
932 | further method calls result in undefined behaviour. |
|
|
933 | |
|
|
934 | The point of this method is to give you a file handle thta you cna pass |
|
|
935 | to another process. In that other process, you can call C<new_from_fh |
|
|
936 | AnyEvent::Fork> to create a new C<AnyEvent::Fork> object from it, thereby |
|
|
937 | effectively passing a fork object to another process. |
|
|
938 | |
|
|
939 | =cut |
|
|
940 | |
|
|
941 | sub to_fh { |
|
|
942 | my ($self, $cb) = @_; |
|
|
943 | |
|
|
944 | $self->[CB] = $cb; |
|
|
945 | |
|
|
946 | unless ($self->[WW]) { |
|
|
947 | $self->[CB]->($self->[FH]); |
|
|
948 | @$self = (); |
|
|
949 | } |
|
|
950 | } |
|
|
951 | |
|
|
952 | =item new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
953 | |
|
|
954 | Takes a file handle originally rceeived by the C<to_fh> method and creates |
|
|
955 | a new C<AnyEvent:Fork> object. The child process itself will not change in |
|
|
956 | any way, i.e. it will keep all the modifications done to it before calling |
|
|
957 | C<to_fh>. |
|
|
958 | |
|
|
959 | The new object is very much like the original object, except that the |
|
|
960 | C<pid> method will return C<undef> even if the process is a direct child. |
|
|
961 | |
|
|
962 | =cut |
|
|
963 | |
|
|
964 | sub new_from_fh { |
|
|
965 | my ($class, $fh) = @_; |
|
|
966 | |
|
|
967 | $class->_new ($fh) |
751 | } |
968 | } |
752 | |
969 | |
753 | =back |
970 | =back |
754 | |
971 | |
755 | =head1 PERFORMANCE |
972 | =head1 PERFORMANCE |
… | |
… | |
765 | |
982 | |
766 | 2079 new processes per second, using manual socketpair + fork |
983 | 2079 new processes per second, using manual socketpair + fork |
767 | |
984 | |
768 | Then I did the same thing, but instead of calling fork, I called |
985 | Then I did the same thing, but instead of calling fork, I called |
769 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
986 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
770 | socket form the child to close on exit. This does the same thing as manual |
987 | socket from the child to close on exit. This does the same thing as manual |
771 | socket pair + fork, except that what is forked is the template process |
988 | socket pair + fork, except that what is forked is the template process |
772 | (2440kB), and the socket needs to be passed to the server at the other end |
989 | (2440kB), and the socket needs to be passed to the server at the other end |
773 | of the socket first. |
990 | of the socket first. |
774 | |
991 | |
775 | 2307 new processes per second, using AnyEvent::Fork->new |
992 | 2307 new processes per second, using AnyEvent::Fork->new |
… | |
… | |
780 | 479 vfork+execs per second, using AnyEvent::Fork->new_exec |
997 | 479 vfork+execs per second, using AnyEvent::Fork->new_exec |
781 | |
998 | |
782 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
999 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
783 | though it uses the same operations, but adds a lot of overhead? |
1000 | though it uses the same operations, but adds a lot of overhead? |
784 | |
1001 | |
785 | The difference is simply the process size: forking the 6MB process takes |
1002 | The difference is simply the process size: forking the 5MB process takes |
786 | so much longer than forking the 2.5MB template process that the overhead |
1003 | so much longer than forking the 2.5MB template process that the extra |
787 | introduced is canceled out. |
1004 | overhead is canceled out. |
788 | |
1005 | |
789 | If the benchmark process grows, the normal fork becomes even slower: |
1006 | If the benchmark process grows, the normal fork becomes even slower: |
790 | |
1007 | |
791 | 1340 new processes, manual fork in a 20MB process |
1008 | 1340 new processes, manual fork of a 20MB process |
792 | 731 new processes, manual fork in a 200MB process |
1009 | 731 new processes, manual fork of a 200MB process |
793 | 235 new processes, manual fork in a 2000MB process |
1010 | 235 new processes, manual fork of a 2000MB process |
794 | |
1011 | |
795 | What that means (to me) is that I can use this module without having a |
1012 | What that means (to me) is that I can use this module without having a bad |
796 | very bad conscience because of the extra overhead required to start new |
1013 | conscience because of the extra overhead required to start new processes. |
797 | processes. |
|
|
798 | |
1014 | |
799 | =head1 TYPICAL PROBLEMS |
1015 | =head1 TYPICAL PROBLEMS |
800 | |
1016 | |
801 | This section lists typical problems that remain. I hope by recognising |
1017 | This section lists typical problems that remain. I hope by recognising |
802 | them, most can be avoided. |
1018 | them, most can be avoided. |
803 | |
1019 | |
804 | =over 4 |
1020 | =over 4 |
805 | |
1021 | |
806 | =item "leaked" file descriptors for exec'ed processes |
1022 | =item leaked file descriptors for exec'ed processes |
807 | |
1023 | |
808 | POSIX systems inherit file descriptors by default when exec'ing a new |
1024 | POSIX systems inherit file descriptors by default when exec'ing a new |
809 | process. While perl itself laudably sets the close-on-exec flags on new |
1025 | process. While perl itself laudably sets the close-on-exec flags on new |
810 | file handles, most C libraries don't care, and even if all cared, it's |
1026 | file handles, most C libraries don't care, and even if all cared, it's |
811 | often not possible to set the flag in a race-free manner. |
1027 | often not possible to set the flag in a race-free manner. |
… | |
… | |
831 | libraries or the code that leaks those file descriptors. |
1047 | libraries or the code that leaks those file descriptors. |
832 | |
1048 | |
833 | Fortunately, most of these leaked descriptors do no harm, other than |
1049 | Fortunately, most of these leaked descriptors do no harm, other than |
834 | sitting on some resources. |
1050 | sitting on some resources. |
835 | |
1051 | |
836 | =item "leaked" file descriptors for fork'ed processes |
1052 | =item leaked file descriptors for fork'ed processes |
837 | |
1053 | |
838 | Normally, L<AnyEvent::Fork> does start new processes by exec'ing them, |
1054 | Normally, L<AnyEvent::Fork> does start new processes by exec'ing them, |
839 | which closes file descriptors not marked for being inherited. |
1055 | which closes file descriptors not marked for being inherited. |
840 | |
1056 | |
841 | However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer |
1057 | However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer |
… | |
… | |
850 | |
1066 | |
851 | The solution is to either not load these modules before use'ing |
1067 | The solution is to either not load these modules before use'ing |
852 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay |
1068 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay |
853 | initialising them, for example, by calling C<init Gtk2> manually. |
1069 | initialising them, for example, by calling C<init Gtk2> manually. |
854 | |
1070 | |
855 | =item exit runs destructors |
1071 | =item exiting calls object destructors |
856 | |
1072 | |
857 | This only applies to users of Lc<AnyEvent::Fork:Early> and |
1073 | This only applies to users of L<AnyEvent::Fork:Early> and |
858 | L<AnyEvent::Fork::Template>. |
1074 | L<AnyEvent::Fork::Template>, or when initialising code creates objects |
|
|
1075 | that reference external resources. |
859 | |
1076 | |
860 | When a process created by AnyEvent::Fork exits, it might do so by calling |
1077 | When a process created by AnyEvent::Fork exits, it might do so by calling |
861 | exit, or simply letting perl reach the end of the program. At which point |
1078 | exit, or simply letting perl reach the end of the program. At which point |
862 | Perl runs all destructors. |
1079 | Perl runs all destructors. |
863 | |
1080 | |
… | |
… | |
882 | to make it so, mostly due to the bloody broken perl that nobody seems to |
1099 | to make it so, mostly due to the bloody broken perl that nobody seems to |
883 | care about. The fork emulation is a bad joke - I have yet to see something |
1100 | care about. The fork emulation is a bad joke - I have yet to see something |
884 | useful that you can do with it without running into memory corruption |
1101 | useful that you can do with it without running into memory corruption |
885 | issues or other braindamage. Hrrrr. |
1102 | issues or other braindamage. Hrrrr. |
886 | |
1103 | |
887 | Cygwin perl is not supported at the moment, as it should implement fd |
1104 | Since fork is endlessly broken on win32 perls (it doesn't even remotely |
888 | passing, but doesn't, and rolling my own is hard, as cygwin doesn't |
1105 | work within it's documented limits) and quite obviously it's not getting |
889 | support enough functionality to do it. |
1106 | improved any time soon, the best way to proceed on windows would be to |
|
|
1107 | always use C<new_exec> and thus never rely on perl's fork "emulation". |
|
|
1108 | |
|
|
1109 | Cygwin perl is not supported at the moment due to some hilarious |
|
|
1110 | shortcomings of its API - see L<IO::FDPoll> for more details. If you never |
|
|
1111 | use C<send_fh> and always use C<new_exec> to create processes, it should |
|
|
1112 | work though. |
890 | |
1113 | |
891 | =head1 SEE ALSO |
1114 | =head1 SEE ALSO |
892 | |
1115 | |
893 | L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter), |
1116 | L<AnyEvent::Fork::Early>, to avoid executing a perl interpreter at all |
|
|
1117 | (part of this distribution). |
|
|
1118 | |
894 | L<AnyEvent::Fork::Template> (to create a process by forking the main |
1119 | L<AnyEvent::Fork::Template>, to create a process by forking the main |
895 | program at a convenient time). |
1120 | program at a convenient time (part of this distribution). |
896 | |
1121 | |
897 | =head1 AUTHOR |
1122 | L<AnyEvent::Fork::RPC>, for simple RPC to child processes (on CPAN). |
|
|
1123 | |
|
|
1124 | L<AnyEvent::Fork::Pool>, for simple worker process pool (on CPAN). |
|
|
1125 | |
|
|
1126 | =head1 AUTHOR AND CONTACT INFORMATION |
898 | |
1127 | |
899 | Marc Lehmann <schmorp@schmorp.de> |
1128 | Marc Lehmann <schmorp@schmorp.de> |
900 | http://home.schmorp.de/ |
1129 | http://software.schmorp.de/pkg/AnyEvent-Fork |
901 | |
1130 | |
902 | =cut |
1131 | =cut |
903 | |
1132 | |
904 | 1 |
1133 | 1 |
905 | |
1134 | |