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34 | |
34 | |
35 | If you need some form of RPC, you could use the AnyEvent::Fork::RPC |
35 | If you need some form of RPC, you could use the AnyEvent::Fork::RPC |
36 | companion module, which adds simple RPC/job queueing to a process |
36 | companion module, which adds simple RPC/job queueing to a process |
37 | created by this module. |
37 | created by this module. |
38 | |
38 | |
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39 | And if you need some automatic process pool management on top of |
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40 | AnyEvent::Fork::RPC, you can look at the AnyEvent::Fork::Pool companion |
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41 | module. |
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42 | |
39 | Or you can implement it yourself in whatever way you like, use some |
43 | Or you can implement it yourself in whatever way you like: use some |
40 | message-passing module such as AnyEvent::MP, some pipe such as |
44 | message-passing module such as AnyEvent::MP, some pipe such as |
41 | AnyEvent::ZeroMQ, use AnyEvent::Handle on both sides to send e.g. JSON |
45 | AnyEvent::ZeroMQ, use AnyEvent::Handle on both sides to send e.g. JSON |
42 | or Storable messages, and so on. |
46 | or Storable messages, and so on. |
43 | |
47 | |
44 | COMPARISON TO OTHER MODULES |
48 | COMPARISON TO OTHER MODULES |
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233 | ->send_arg ("/bin/echo", "hi") |
237 | ->send_arg ("/bin/echo", "hi") |
234 | ->run ("run", my $cv = AE::cv); |
238 | ->run ("run", my $cv = AE::cv); |
235 | |
239 | |
236 | my $stderr = $cv->recv; |
240 | my $stderr = $cv->recv; |
237 | |
241 | |
238 | CONCEPTS |
242 | For stingy users: put the worker code into a "DATA" section. |
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243 | When you want to be stingy with files, you cna put your code into the |
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244 | "DATA" section of your module (or program): |
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245 | |
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246 | use AnyEvent::Fork; |
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247 | |
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248 | AnyEvent::Fork |
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249 | ->new |
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250 | ->eval (do { local $/; <DATA> }) |
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251 | ->run ("doit", sub { ... }); |
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252 | |
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253 | __DATA__ |
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254 | |
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255 | sub doit { |
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256 | ... do something! |
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257 | } |
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258 | |
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259 | For stingy standalone programs: do not rely on external files at |
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260 | all. |
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261 | For single-file scripts it can be inconvenient to rely on external files |
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262 | - even when using < "DATA" section, you still need to "exec" an external |
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263 | perl interpreter, which might not be available when using |
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264 | App::Staticperl, Urlader or PAR::Packer for example. |
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265 | |
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266 | Two modules help here - AnyEvent::Fork::Early forks a template process |
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267 | for all further calls to "new_exec", and AnyEvent::Fork::Template forks |
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268 | the main program as a template process. |
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269 | |
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270 | Here is how your main program should look like: |
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271 | |
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272 | #! perl |
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273 | |
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274 | # optional, as the very first thing. |
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275 | # in case modules want to create their own processes. |
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276 | use AnyEvent::Fork::Early; |
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277 | |
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278 | # next, load all modules you need in your template process |
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279 | use Example::My::Module |
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280 | use Example::Whatever; |
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281 | |
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282 | # next, put your run function definition and anything else you |
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283 | # need, but do not use code outside of BEGIN blocks. |
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284 | sub worker_run { |
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285 | my ($fh, @args) = @_; |
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286 | ... |
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287 | } |
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288 | |
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289 | # now preserve everything so far as AnyEvent::Fork object |
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290 | # in §TEMPLATE. |
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291 | use AnyEvent::Fork::Template; |
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292 | |
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293 | # do not put code outside of BEGIN blocks until here |
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294 | |
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295 | # now use the $TEMPLATE process in any way you like |
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296 | |
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297 | # for example: create 10 worker processes |
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298 | my @worker; |
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299 | my $cv = AE::cv; |
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300 | for (1..10) { |
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301 | $cv->begin; |
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302 | $TEMPLATE->fork->send_arg ($_)->run ("worker_run", sub { |
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303 | push @worker, shift; |
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304 | $cv->end; |
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305 | }); |
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306 | } |
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307 | $cv->recv; |
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308 | |
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309 | lhead1 CONCEPTS |
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310 | |
239 | This module can create new processes either by executing a new perl |
311 | This module can create new processes either by executing a new perl |
240 | process, or by forking from an existing "template" process. |
312 | process, or by forking from an existing "template" process. |
241 | |
313 | |
242 | All these processes are called "child processes" (whether they are |
314 | All these processes are called "child processes" (whether they are |
243 | direct children or not), while the process that manages them is called |
315 | direct children or not), while the process that manages them is called |
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… | |
504 | my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_; |
576 | my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_; |
505 | |
577 | |
506 | print scalar <$fh>; # prints "hi #1\n" and "hi #2\n" in any order |
578 | print scalar <$fh>; # prints "hi #1\n" and "hi #2\n" in any order |
507 | } |
579 | } |
508 | |
580 | |
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581 | $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED |
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582 | Flushes all commands out to the process and then calls the callback |
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583 | with the communications socket. |
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584 | |
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585 | The process object becomes unusable on return from this function - |
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586 | any further method calls result in undefined behaviour. |
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587 | |
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588 | The point of this method is to give you a file handle thta you cna |
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589 | pass to another process. In that other process, you can call |
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590 | "new_from_fh AnyEvent::Fork" to create a new "AnyEvent::Fork" object |
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591 | from it, thereby effectively passing a fork object to another |
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592 | process. |
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593 | |
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594 | new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED |
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595 | Takes a file handle originally rceeived by the "to_fh" method and |
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596 | creates a new "AnyEvent:Fork" object. The child process itself will |
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597 | not change in any way, i.e. it will keep all the modifications done |
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598 | to it before calling "to_fh". |
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599 | |
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600 | The new object is very much like the original object, except that |
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601 | the "pid" method will return "undef" even if the process is a direct |
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602 | child. |
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603 | |
509 | PERFORMANCE |
604 | PERFORMANCE |
510 | Now for some unscientific benchmark numbers (all done on an amd64 |
605 | Now for some unscientific benchmark numbers (all done on an amd64 |
511 | GNU/Linux box). These are intended to give you an idea of the relative |
606 | GNU/Linux box). These are intended to give you an idea of the relative |
512 | performance you can expect, they are not meant to be absolute |
607 | performance you can expect, they are not meant to be absolute |
513 | performance numbers. |
608 | performance numbers. |
… | |
… | |
519 | |
614 | |
520 | 2079 new processes per second, using manual socketpair + fork |
615 | 2079 new processes per second, using manual socketpair + fork |
521 | |
616 | |
522 | Then I did the same thing, but instead of calling fork, I called |
617 | Then I did the same thing, but instead of calling fork, I called |
523 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
618 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
524 | socket form the child to close on exit. This does the same thing as |
619 | socket from the child to close on exit. This does the same thing as |
525 | manual socket pair + fork, except that what is forked is the template |
620 | manual socket pair + fork, except that what is forked is the template |
526 | process (2440kB), and the socket needs to be passed to the server at the |
621 | process (2440kB), and the socket needs to be passed to the server at the |
527 | other end of the socket first. |
622 | other end of the socket first. |
528 | |
623 | |
529 | 2307 new processes per second, using AnyEvent::Fork->new |
624 | 2307 new processes per second, using AnyEvent::Fork->new |
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… | |
629 | and sweat to make it so, mostly due to the bloody broken perl that |
724 | and sweat to make it so, mostly due to the bloody broken perl that |
630 | nobody seems to care about. The fork emulation is a bad joke - I have |
725 | nobody seems to care about. The fork emulation is a bad joke - I have |
631 | yet to see something useful that you can do with it without running into |
726 | yet to see something useful that you can do with it without running into |
632 | memory corruption issues or other braindamage. Hrrrr. |
727 | memory corruption issues or other braindamage. Hrrrr. |
633 | |
728 | |
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729 | Since fork is endlessly broken on win32 perls (it doesn't even remotely |
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730 | work within it's documented limits) and quite obviously it's not getting |
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731 | improved any time soon, the best way to proceed on windows would be to |
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732 | always use "new_exec" and thus never rely on perl's fork "emulation". |
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733 | |
634 | Cygwin perl is not supported at the moment due to some hilarious |
734 | Cygwin perl is not supported at the moment due to some hilarious |
635 | shortcomings of its API - see IO::FDPoll for more details. |
735 | shortcomings of its API - see IO::FDPoll for more details. If you never |
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736 | use "send_fh" and always use "new_exec" to create processes, it should |
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737 | work though. |
636 | |
738 | |
637 | SEE ALSO |
739 | SEE ALSO |
638 | AnyEvent::Fork::Early, to avoid executing a perl interpreter at all |
740 | AnyEvent::Fork::Early, to avoid executing a perl interpreter at all |
639 | (part of this distribution). |
741 | (part of this distribution). |
640 | |
742 | |
641 | AnyEvent::Fork::Template, to create a process by forking the main |
743 | AnyEvent::Fork::Template, to create a process by forking the main |
642 | program at a convenient time (part of this distribution). |
744 | program at a convenient time (part of this distribution). |
643 | |
745 | |
644 | AnyEvent::Fork::RPC, for simple RPC to child processes (on CPAN). |
746 | AnyEvent::Fork::RPC, for simple RPC to child processes (on CPAN). |
645 | |
747 | |
|
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748 | AnyEvent::Fork::Pool, for simple worker process pool (on CPAN). |
|
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749 | |
646 | AUTHOR AND CONTACT INFORMATION |
750 | AUTHOR AND CONTACT INFORMATION |
647 | Marc Lehmann <schmorp@schmorp.de> |
751 | Marc Lehmann <schmorp@schmorp.de> |
648 | http://software.schmorp.de/pkg/AnyEvent-Fork |
752 | http://software.schmorp.de/pkg/AnyEvent-Fork |
649 | |
753 | |