… | |
… | |
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. |
… | |
… | |
40 | in whatever way you like, use some message-passing module such |
40 | in whatever way you like, use some message-passing module such |
41 | as L<AnyEvent::MP>, some pipe such as L<AnyEvent::ZeroMQ>, use |
41 | as L<AnyEvent::MP>, some pipe such as L<AnyEvent::ZeroMQ>, use |
42 | L<AnyEvent::Handle> on both sides to send e.g. JSON or Storable messages, |
42 | L<AnyEvent::Handle> on both sides to send e.g. JSON or Storable messages, |
43 | and so on. |
43 | and so on. |
44 | |
44 | |
|
|
45 | =head2 COMPARISON TO OTHER MODULES |
|
|
46 | |
|
|
47 | There is an abundance of modules on CPAN that do "something fork", such as |
|
|
48 | L<Parallel::ForkManager>, L<AnyEvent::ForkManager>, L<AnyEvent::Worker> |
|
|
49 | or L<AnyEvent::Subprocess>. There are modules that implement their own |
|
|
50 | process management, such as L<AnyEvent::DBI>. |
|
|
51 | |
|
|
52 | The problems that all these modules try to solve are real, however, none |
|
|
53 | of them (from what I have seen) tackle the very real problems of unwanted |
|
|
54 | memory sharing, efficiency, not being able to use event processing or |
|
|
55 | similar modules in the processes they create. |
|
|
56 | |
|
|
57 | This module doesn't try to replace any of them - instead it tries to solve |
|
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58 | the problem of creating processes with a minimum of fuss and overhead (and |
|
|
59 | also luxury). Ideally, most of these would use AnyEvent::Fork internally, |
|
|
60 | except they were written before AnyEvent:Fork was available, so obviously |
|
|
61 | had to roll their own. |
|
|
62 | |
45 | =head1 PROBLEM STATEMENT |
63 | =head2 PROBLEM STATEMENT |
46 | |
64 | |
47 | There are two traditional ways to implement parallel processing on UNIX |
65 | There are two traditional ways to implement parallel processing on UNIX |
48 | like operating systems - fork and process, and fork+exec and process. They |
66 | like operating systems - fork and process, and fork+exec and process. They |
49 | have different advantages and disadvantages that I describe below, |
67 | have different advantages and disadvantages that I describe below, |
50 | together with how this module tries to mitigate the disadvantages. |
68 | together with how this module tries to mitigate the disadvantages. |
… | |
… | |
152 | |
170 | |
153 | # now $master_filehandle is connected to the |
171 | # now $master_filehandle is connected to the |
154 | # $slave_filehandle in the new process. |
172 | # $slave_filehandle in the new process. |
155 | }); |
173 | }); |
156 | |
174 | |
157 | MyModule::worker might look like this: |
175 | C<MyModule> might look like this: |
158 | |
176 | |
|
|
177 | package MyModule; |
|
|
178 | |
159 | sub MyModule::worker { |
179 | sub worker { |
160 | my ($slave_filehandle) = @_; |
180 | my ($slave_filehandle) = @_; |
161 | |
181 | |
162 | # now $slave_filehandle is connected to the $master_filehandle |
182 | # now $slave_filehandle is connected to the $master_filehandle |
163 | # in the original prorcess. have fun! |
183 | # in the original prorcess. have fun! |
164 | } |
184 | } |
… | |
… | |
183 | } |
203 | } |
184 | |
204 | |
185 | # now do other things - maybe use the filehandle provided by run |
205 | # now do other things - maybe use the filehandle provided by run |
186 | # to wait for the processes to die. or whatever. |
206 | # to wait for the processes to die. or whatever. |
187 | |
207 | |
188 | My::Server::run might look like this: |
208 | C<My::Server> might look like this: |
189 | |
209 | |
190 | sub My::Server::run { |
210 | package My::Server; |
|
|
211 | |
|
|
212 | sub run { |
191 | my ($slave, $listener, $id) = @_; |
213 | my ($slave, $listener, $id) = @_; |
192 | |
214 | |
193 | close $slave; # we do not use the socket, so close it to save resources |
215 | close $slave; # we do not use the socket, so close it to save resources |
194 | |
216 | |
195 | # we could go ballistic and use e.g. AnyEvent here, or IO::AIO, |
217 | # we could go ballistic and use e.g. AnyEvent here, or IO::AIO, |
… | |
… | |
199 | } |
221 | } |
200 | } |
222 | } |
201 | |
223 | |
202 | =head2 use AnyEvent::Fork as a faster fork+exec |
224 | =head2 use AnyEvent::Fork as a faster fork+exec |
203 | |
225 | |
204 | This runs /bin/echo hi, with stdout redirected to /tmp/log and stderr to |
226 | This runs C</bin/echo hi>, with stdandard output redirected to /tmp/log |
205 | the communications socket. It is usually faster than fork+exec, but still |
227 | and standard error redirected to the communications socket. It is usually |
206 | let's you prepare the environment. |
228 | faster than fork+exec, but still lets you prepare the environment. |
207 | |
229 | |
208 | open my $output, ">/tmp/log" or die "$!"; |
230 | open my $output, ">/tmp/log" or die "$!"; |
209 | |
231 | |
210 | AnyEvent::Fork |
232 | AnyEvent::Fork |
211 | ->new |
233 | ->new |
212 | ->eval (' |
234 | ->eval (' |
|
|
235 | # compile a helper function for later use |
213 | sub run { |
236 | sub run { |
214 | my ($fh, $output, @cmd) = @_; |
237 | my ($fh, $output, @cmd) = @_; |
215 | |
238 | |
216 | # perl will clear close-on-exec on STDOUT/STDERR |
239 | # perl will clear close-on-exec on STDOUT/STDERR |
217 | open STDOUT, ">&", $output or die; |
240 | open STDOUT, ">&", $output or die; |
… | |
… | |
347 | use AnyEvent; |
370 | use AnyEvent; |
348 | use AnyEvent::Util (); |
371 | use AnyEvent::Util (); |
349 | |
372 | |
350 | use IO::FDPass; |
373 | use IO::FDPass; |
351 | |
374 | |
352 | our $VERSION = 0.5; |
375 | our $VERSION = 0.6; |
353 | |
|
|
354 | our $PERL; # the path to the perl interpreter, deduces with various forms of magic |
|
|
355 | |
376 | |
356 | =over 4 |
377 | =over 4 |
357 | |
378 | |
358 | =back |
379 | =back |
359 | |
380 | |
… | |
… | |
362 | # the early fork template process |
383 | # the early fork template process |
363 | our $EARLY; |
384 | our $EARLY; |
364 | |
385 | |
365 | # the empty template process |
386 | # the empty template process |
366 | our $TEMPLATE; |
387 | our $TEMPLATE; |
|
|
388 | |
|
|
389 | sub QUEUE() { 0 } |
|
|
390 | sub FH() { 1 } |
|
|
391 | sub WW() { 2 } |
|
|
392 | sub PID() { 3 } |
|
|
393 | sub CB() { 4 } |
|
|
394 | |
|
|
395 | sub _new { |
|
|
396 | my ($self, $fh, $pid) = @_; |
|
|
397 | |
|
|
398 | AnyEvent::Util::fh_nonblocking $fh, 1; |
|
|
399 | |
|
|
400 | $self = bless [ |
|
|
401 | [], # write queue - strings or fd's |
|
|
402 | $fh, |
|
|
403 | undef, # AE watcher |
|
|
404 | $pid, |
|
|
405 | ], $self; |
|
|
406 | |
|
|
407 | $self |
|
|
408 | } |
367 | |
409 | |
368 | sub _cmd { |
410 | sub _cmd { |
369 | my $self = shift; |
411 | my $self = shift; |
370 | |
412 | |
371 | # ideally, we would want to use "a (w/a)*" as format string, but perl |
413 | # ideally, we would want to use "a (w/a)*" as format string, but perl |
372 | # versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack |
414 | # versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack |
373 | # it. |
415 | # it. |
374 | push @{ $self->[2] }, pack "a L/a*", $_[0], $_[1]; |
416 | push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1]; |
375 | |
417 | |
376 | $self->[3] ||= AE::io $self->[1], 1, sub { |
418 | $self->[WW] ||= AE::io $self->[FH], 1, sub { |
377 | do { |
419 | do { |
378 | # send the next "thing" in the queue - either a reference to an fh, |
420 | # send the next "thing" in the queue - either a reference to an fh, |
379 | # or a plain string. |
421 | # or a plain string. |
380 | |
422 | |
381 | if (ref $self->[2][0]) { |
423 | if (ref $self->[QUEUE][0]) { |
382 | # send fh |
424 | # send fh |
383 | unless (IO::FDPass::send fileno $self->[1], fileno ${ $self->[2][0] }) { |
425 | unless (IO::FDPass::send fileno $self->[FH], fileno ${ $self->[QUEUE][0] }) { |
384 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
426 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
385 | undef $self->[3]; |
427 | undef $self->[WW]; |
386 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
428 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
387 | } |
429 | } |
388 | |
430 | |
389 | shift @{ $self->[2] }; |
431 | shift @{ $self->[QUEUE] }; |
390 | |
432 | |
391 | } else { |
433 | } else { |
392 | # send string |
434 | # send string |
393 | my $len = syswrite $self->[1], $self->[2][0]; |
435 | my $len = syswrite $self->[FH], $self->[QUEUE][0]; |
394 | |
436 | |
395 | unless ($len) { |
437 | unless ($len) { |
396 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
438 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
397 | undef $self->[3]; |
439 | undef $self->[3]; |
398 | die "AnyEvent::Fork: command write failure: $!"; |
440 | die "AnyEvent::Fork: command write failure: $!"; |
399 | } |
441 | } |
400 | |
442 | |
401 | substr $self->[2][0], 0, $len, ""; |
443 | substr $self->[QUEUE][0], 0, $len, ""; |
402 | shift @{ $self->[2] } unless length $self->[2][0]; |
444 | shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0]; |
403 | } |
445 | } |
404 | } while @{ $self->[2] }; |
446 | } while @{ $self->[QUEUE] }; |
405 | |
447 | |
406 | # everything written |
448 | # everything written |
407 | undef $self->[3]; |
449 | undef $self->[WW]; |
408 | |
450 | |
409 | # invoke run callback, if any |
451 | # invoke run callback, if any |
410 | $self->[4]->($self->[1]) if $self->[4]; |
452 | $self->[CB]->($self->[FH]) if $self->[CB]; |
411 | }; |
453 | }; |
412 | |
454 | |
413 | () # make sure we don't leak the watcher |
455 | () # make sure we don't leak the watcher |
414 | } |
|
|
415 | |
|
|
416 | sub _new { |
|
|
417 | my ($self, $fh, $pid) = @_; |
|
|
418 | |
|
|
419 | AnyEvent::Util::fh_nonblocking $fh, 1; |
|
|
420 | |
|
|
421 | $self = bless [ |
|
|
422 | $pid, |
|
|
423 | $fh, |
|
|
424 | [], # write queue - strings or fd's |
|
|
425 | undef, # AE watcher |
|
|
426 | ], $self; |
|
|
427 | |
|
|
428 | $self |
|
|
429 | } |
456 | } |
430 | |
457 | |
431 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
458 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
432 | sub _new_fork { |
459 | sub _new_fork { |
433 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
460 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
… | |
… | |
438 | if ($pid eq 0) { |
465 | if ($pid eq 0) { |
439 | require AnyEvent::Fork::Serve; |
466 | require AnyEvent::Fork::Serve; |
440 | $AnyEvent::Fork::Serve::OWNER = $parent; |
467 | $AnyEvent::Fork::Serve::OWNER = $parent; |
441 | close $fh; |
468 | close $fh; |
442 | $0 = "$_[1] of $parent"; |
469 | $0 = "$_[1] of $parent"; |
443 | $SIG{CHLD} = 'IGNORE'; |
|
|
444 | AnyEvent::Fork::Serve::serve ($slave); |
470 | AnyEvent::Fork::Serve::serve ($slave); |
445 | exit 0; |
471 | exit 0; |
446 | } elsif (!$pid) { |
472 | } elsif (!$pid) { |
447 | die "AnyEvent::Fork::Early/Template: unable to fork template process: $!"; |
473 | die "AnyEvent::Fork::Early/Template: unable to fork template process: $!"; |
448 | } |
474 | } |
… | |
… | |
555 | } |
581 | } |
556 | |
582 | |
557 | =item $pid = $proc->pid |
583 | =item $pid = $proc->pid |
558 | |
584 | |
559 | Returns the process id of the process I<iff it is a direct child of the |
585 | Returns the process id of the process I<iff it is a direct child of the |
560 | process> running AnyEvent::Fork, and C<undef> otherwise. |
586 | process running AnyEvent::Fork>, and C<undef> otherwise. |
561 | |
587 | |
562 | Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and |
588 | Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and |
563 | L<AnyEvent::Fork::Template> are direct children, and you are responsible |
589 | L<AnyEvent::Fork::Template> are direct children, and you are responsible |
564 | to clean up their zombies when they die. |
590 | to clean up their zombies when they die. |
565 | |
591 | |
… | |
… | |
567 | AnyEvent::Fork itself. |
593 | AnyEvent::Fork itself. |
568 | |
594 | |
569 | =cut |
595 | =cut |
570 | |
596 | |
571 | sub pid { |
597 | sub pid { |
572 | $_[0][0] |
598 | $_[0][PID] |
573 | } |
599 | } |
574 | |
600 | |
575 | =item $proc = $proc->eval ($perlcode, @args) |
601 | =item $proc = $proc->eval ($perlcode, @args) |
576 | |
602 | |
577 | Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to |
603 | Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to |
… | |
… | |
583 | |
609 | |
584 | The code will usually be executed after this call returns, and there is no |
610 | The code will usually be executed after this call returns, and there is no |
585 | way to pass anything back to the calling process. Any evaluation errors |
611 | way to pass anything back to the calling process. Any evaluation errors |
586 | will be reported to stderr and cause the process to exit. |
612 | will be reported to stderr and cause the process to exit. |
587 | |
613 | |
588 | If you want to execute some code to take over the process (see the |
614 | If you want to execute some code (that isn't in a module) to take over the |
589 | "fork+exec" example in the SYNOPSIS), you should compile a function via |
615 | process, you should compile a function via C<eval> first, and then call |
590 | C<eval> first, and then call it via C<run>. This also gives you access to |
616 | it via C<run>. This also gives you access to any arguments passed via the |
591 | any arguments passed via the C<send_xxx> methods, such as file handles. |
617 | C<send_xxx> methods, such as file handles. See the L<use AnyEvent::Fork as |
|
|
618 | a faster fork+exec> example to see it in action. |
592 | |
619 | |
593 | Returns the process object for easy chaining of method calls. |
620 | Returns the process object for easy chaining of method calls. |
594 | |
621 | |
595 | =cut |
622 | =cut |
596 | |
623 | |
… | |
… | |
622 | =item $proc = $proc->send_fh ($handle, ...) |
649 | =item $proc = $proc->send_fh ($handle, ...) |
623 | |
650 | |
624 | Send one or more file handles (I<not> file descriptors) to the process, |
651 | Send one or more file handles (I<not> file descriptors) to the process, |
625 | to prepare a call to C<run>. |
652 | to prepare a call to C<run>. |
626 | |
653 | |
627 | The process object keeps a reference to the handles until this is done, |
654 | The process object keeps a reference to the handles until they have |
628 | so you must not explicitly close the handles. This is most easily |
655 | been passed over to the process, so you must not explicitly close the |
629 | accomplished by simply not storing the file handles anywhere after passing |
656 | handles. This is most easily accomplished by simply not storing the file |
630 | them to this method. |
657 | handles anywhere after passing them to this method - when AnyEvent::Fork |
|
|
658 | is finished using them, perl will automatically close them. |
631 | |
659 | |
632 | Returns the process object for easy chaining of method calls. |
660 | Returns the process object for easy chaining of method calls. |
633 | |
661 | |
634 | Example: pass a file handle to a process, and release it without |
662 | Example: pass a file handle to a process, and release it without |
635 | closing. It will be closed automatically when it is no longer used. |
663 | closing. It will be closed automatically when it is no longer used. |
… | |
… | |
642 | sub send_fh { |
670 | sub send_fh { |
643 | my ($self, @fh) = @_; |
671 | my ($self, @fh) = @_; |
644 | |
672 | |
645 | for my $fh (@fh) { |
673 | for my $fh (@fh) { |
646 | $self->_cmd ("h"); |
674 | $self->_cmd ("h"); |
647 | push @{ $self->[2] }, \$fh; |
675 | push @{ $self->[QUEUE] }, \$fh; |
648 | } |
676 | } |
649 | |
677 | |
650 | $self |
678 | $self |
651 | } |
679 | } |
652 | |
680 | |
653 | =item $proc = $proc->send_arg ($string, ...) |
681 | =item $proc = $proc->send_arg ($string, ...) |
654 | |
682 | |
655 | Send one or more argument strings to the process, to prepare a call to |
683 | Send one or more argument strings to the process, to prepare a call to |
656 | C<run>. The strings can be any octet string. |
684 | C<run>. The strings can be any octet strings. |
657 | |
685 | |
658 | The protocol is optimised to pass a moderate number of relatively short |
686 | The protocol is optimised to pass a moderate number of relatively short |
659 | strings - while you can pass up to 4GB of data in one go, this is more |
687 | strings - while you can pass up to 4GB of data in one go, this is more |
660 | meant to pass some ID information or other startup info, not big chunks of |
688 | meant to pass some ID information or other startup info, not big chunks of |
661 | data. |
689 | data. |
… | |
… | |
677 | Enter the function specified by the function name in C<$func> in the |
705 | Enter the function specified by the function name in C<$func> in the |
678 | process. The function is called with the communication socket as first |
706 | process. The function is called with the communication socket as first |
679 | argument, followed by all file handles and string arguments sent earlier |
707 | argument, followed by all file handles and string arguments sent earlier |
680 | via C<send_fh> and C<send_arg> methods, in the order they were called. |
708 | via C<send_fh> and C<send_arg> methods, in the order they were called. |
681 | |
709 | |
|
|
710 | The process object becomes unusable on return from this function - any |
|
|
711 | further method calls result in undefined behaviour. |
|
|
712 | |
682 | The function name should be fully qualified, but if it isn't, it will be |
713 | The function name should be fully qualified, but if it isn't, it will be |
683 | looked up in the main package. |
714 | looked up in the C<main> package. |
684 | |
715 | |
685 | If the called function returns, doesn't exist, or any error occurs, the |
716 | If the called function returns, doesn't exist, or any error occurs, the |
686 | process exits. |
717 | process exits. |
687 | |
718 | |
688 | Preparing the process is done in the background - when all commands have |
719 | Preparing the process is done in the background - when all commands have |
689 | been sent, the callback is invoked with the local communications socket |
720 | been sent, the callback is invoked with the local communications socket |
690 | as argument. At this point you can start using the socket in any way you |
721 | as argument. At this point you can start using the socket in any way you |
691 | like. |
722 | like. |
692 | |
|
|
693 | The process object becomes unusable on return from this function - any |
|
|
694 | further method calls result in undefined behaviour. |
|
|
695 | |
723 | |
696 | If the communication socket isn't used, it should be closed on both sides, |
724 | If the communication socket isn't used, it should be closed on both sides, |
697 | to save on kernel memory. |
725 | to save on kernel memory. |
698 | |
726 | |
699 | The socket is non-blocking in the parent, and blocking in the newly |
727 | The socket is non-blocking in the parent, and blocking in the newly |
… | |
… | |
738 | =cut |
766 | =cut |
739 | |
767 | |
740 | sub run { |
768 | sub run { |
741 | my ($self, $func, $cb) = @_; |
769 | my ($self, $func, $cb) = @_; |
742 | |
770 | |
743 | $self->[4] = $cb; |
771 | $self->[CB] = $cb; |
744 | $self->_cmd (r => $func); |
772 | $self->_cmd (r => $func); |
745 | } |
773 | } |
746 | |
774 | |
747 | =back |
775 | =back |
748 | |
776 | |
… | |
… | |
774 | 479 vfork+execs per second, using AnyEvent::Fork->new_exec |
802 | 479 vfork+execs per second, using AnyEvent::Fork->new_exec |
775 | |
803 | |
776 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
804 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
777 | though it uses the same operations, but adds a lot of overhead? |
805 | though it uses the same operations, but adds a lot of overhead? |
778 | |
806 | |
779 | The difference is simply the process size: forking the 6MB process takes |
807 | The difference is simply the process size: forking the 5MB process takes |
780 | so much longer than forking the 2.5MB template process that the overhead |
808 | so much longer than forking the 2.5MB template process that the extra |
781 | introduced is canceled out. |
809 | overhead introduced is canceled out. |
782 | |
810 | |
783 | If the benchmark process grows, the normal fork becomes even slower: |
811 | If the benchmark process grows, the normal fork becomes even slower: |
784 | |
812 | |
785 | 1340 new processes, manual fork in a 20MB process |
813 | 1340 new processes, manual fork of a 20MB process |
786 | 731 new processes, manual fork in a 200MB process |
814 | 731 new processes, manual fork of a 200MB process |
787 | 235 new processes, manual fork in a 2000MB process |
815 | 235 new processes, manual fork of a 2000MB process |
788 | |
816 | |
789 | What that means (to me) is that I can use this module without having a |
817 | What that means (to me) is that I can use this module without having a bad |
790 | very bad conscience because of the extra overhead required to start new |
818 | conscience because of the extra overhead required to start new processes. |
791 | processes. |
|
|
792 | |
819 | |
793 | =head1 TYPICAL PROBLEMS |
820 | =head1 TYPICAL PROBLEMS |
794 | |
821 | |
795 | This section lists typical problems that remain. I hope by recognising |
822 | This section lists typical problems that remain. I hope by recognising |
796 | them, most can be avoided. |
823 | them, most can be avoided. |
797 | |
824 | |
798 | =over 4 |
825 | =over 4 |
799 | |
826 | |
800 | =item "leaked" file descriptors for exec'ed processes |
827 | =item leaked file descriptors for exec'ed processes |
801 | |
828 | |
802 | POSIX systems inherit file descriptors by default when exec'ing a new |
829 | POSIX systems inherit file descriptors by default when exec'ing a new |
803 | process. While perl itself laudably sets the close-on-exec flags on new |
830 | process. While perl itself laudably sets the close-on-exec flags on new |
804 | file handles, most C libraries don't care, and even if all cared, it's |
831 | file handles, most C libraries don't care, and even if all cared, it's |
805 | often not possible to set the flag in a race-free manner. |
832 | often not possible to set the flag in a race-free manner. |
… | |
… | |
825 | libraries or the code that leaks those file descriptors. |
852 | libraries or the code that leaks those file descriptors. |
826 | |
853 | |
827 | Fortunately, most of these leaked descriptors do no harm, other than |
854 | Fortunately, most of these leaked descriptors do no harm, other than |
828 | sitting on some resources. |
855 | sitting on some resources. |
829 | |
856 | |
830 | =item "leaked" file descriptors for fork'ed processes |
857 | =item leaked file descriptors for fork'ed processes |
831 | |
858 | |
832 | Normally, L<AnyEvent::Fork> does start new processes by exec'ing them, |
859 | Normally, L<AnyEvent::Fork> does start new processes by exec'ing them, |
833 | which closes file descriptors not marked for being inherited. |
860 | which closes file descriptors not marked for being inherited. |
834 | |
861 | |
835 | However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer |
862 | However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer |
… | |
… | |
844 | |
871 | |
845 | The solution is to either not load these modules before use'ing |
872 | The solution is to either not load these modules before use'ing |
846 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay |
873 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay |
847 | initialising them, for example, by calling C<init Gtk2> manually. |
874 | initialising them, for example, by calling C<init Gtk2> manually. |
848 | |
875 | |
849 | =item exit runs destructors |
876 | =item exiting calls object destructors |
850 | |
877 | |
851 | This only applies to users of Lc<AnyEvent::Fork:Early> and |
878 | This only applies to users of L<AnyEvent::Fork:Early> and |
852 | L<AnyEvent::Fork::Template>. |
879 | L<AnyEvent::Fork::Template>, or when initialiasing code creates objects |
|
|
880 | that reference external resources. |
853 | |
881 | |
854 | When a process created by AnyEvent::Fork exits, it might do so by calling |
882 | When a process created by AnyEvent::Fork exits, it might do so by calling |
855 | exit, or simply letting perl reach the end of the program. At which point |
883 | exit, or simply letting perl reach the end of the program. At which point |
856 | Perl runs all destructors. |
884 | Perl runs all destructors. |
857 | |
885 | |
… | |
… | |
876 | to make it so, mostly due to the bloody broken perl that nobody seems to |
904 | to make it so, mostly due to the bloody broken perl that nobody seems to |
877 | care about. The fork emulation is a bad joke - I have yet to see something |
905 | care about. The fork emulation is a bad joke - I have yet to see something |
878 | useful that you can do with it without running into memory corruption |
906 | useful that you can do with it without running into memory corruption |
879 | issues or other braindamage. Hrrrr. |
907 | issues or other braindamage. Hrrrr. |
880 | |
908 | |
881 | Cygwin perl is not supported at the moment, as it should implement fd |
909 | Cygwin perl is not supported at the moment due to some hilarious |
882 | passing, but doesn't, and rolling my own is hard, as cygwin doesn't |
910 | shortcomings of its API - see L<IO::FDPoll> for more details. |
883 | support enough functionality to do it. |
|
|
884 | |
911 | |
885 | =head1 SEE ALSO |
912 | =head1 SEE ALSO |
886 | |
913 | |
887 | L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter), |
914 | L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter), |
888 | L<AnyEvent::Fork::Template> (to create a process by forking the main |
915 | L<AnyEvent::Fork::Template> (to create a process by forking the main |