[ViewVC] Diff of: cvs/AnyEvent-Fork/Fork.pm

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.42 by root, Mon Apr 8 05:44:23 2013 UTC vs.
Revision 1.60 by root, Wed Sep 25 11:05:30 2013 UTC

…		…
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 = 1.2;
376
377	=over 4
378
379	=back
380
381	=cut
382		456
383	# the early fork template process	457	# the early fork template process
384	our $EARLY;	458	our $EARLY;
385		459
386	# the empty template process	460	# the empty template process
…		…
434	# send string	508	# send string
435	my $len = syswrite $self->[FH], $self->[QUEUE][0];	509	my $len = syswrite $self->[FH], $self->[QUEUE][0];
436		510
437	unless ($len) {	511	unless ($len) {
438	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;	512	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;
439	undef $self->[3];	513	undef $self->[WW];
440	die "AnyEvent::Fork: command write failure: $!";	514	die "AnyEvent::Fork: command write failure: $!";
441	}	515	}
442		516
443	substr $self->[QUEUE][0], 0, $len, "";	517	substr $self->[QUEUE][0], 0, $len, "";
444	shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0];	518	shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0];
…		…
447		521
448	# everything written	522	# everything written
449	undef $self->[WW];	523	undef $self->[WW];
450		524
451	# invoke run callback, if any	525	# invoke run callback, if any
		526	if ($self->[CB]) {
452	$self->[CB]->($self->[FH]) if $self->[CB];	527	$self->[CB]->($self->[FH]);
		528	@$self = ();
		529	}
453	};	530	};
454		531
455	() # make sure we don't leak the watcher	532	() # make sure we don't leak the watcher
456	}	533	}
457		534
…		…
528		605
529	You should use C<new> whenever possible, except when having a template	606	You should use C<new> whenever possible, except when having a template
530	process around is unacceptable.	607	process around is unacceptable.
531		608
532	The path to the perl interpreter is divined using various methods - first	609	The path to the perl interpreter is divined using various methods - first
533	C<$^X> is investigated to see if the path ends with something that sounds	610	C<$^X> is investigated to see if the path ends with something that looks
534	as if it were the perl interpreter. Failing this, the module falls back to	611	as if it were the perl interpreter. Failing this, the module falls back to
535	using C<$Config::Config{perlpath}>.	612	using C<$Config::Config{perlpath}>.
536		613
		614	The path to perl can also be overriden by setting the global variable
		615	C<$AnyEvent::Fork::PERL> - it's value will be used for all subsequent
		616	invocations.
		617
537	=cut	618	=cut
		619
		620	our $PERL;
538		621
539	sub new_exec {	622	sub new_exec {
540	my ($self) = @_;	623	my ($self) = @_;
541		624
542	return $EARLY->fork	625	return $EARLY->fork
543	if $EARLY;	626	if $EARLY;
544		627
		628	unless (defined $PERL) {
545	# first find path of perl	629	# first find path of perl
546	my $perl = $;	630	my $perl = $;
547		631
548	# first we try $^X, but the path must be absolute (always on win32), and end in sth.	632	# first we try $^X, but the path must be absolute (always on win32), and end in sth.
549	# that looks like perl. this obviously only works for posix and win32	633	# that looks like perl. this obviously only works for posix and win32
550	unless (	634	unless (
551	($^O eq "MSWin32" \|\| $perl =~ m%^/%)	635	($^O eq "MSWin32" \|\| $perl =~ m%^/%)
552	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i	636	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i
553	) {	637	) {
554	# if it doesn't look perlish enough, try Config	638	# if it doesn't look perlish enough, try Config
555	require Config;	639	require Config;
556	$perl = $Config::Config{perlpath};	640	$perl = $Config::Config{perlpath};
557	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;	641	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;
		642	}
		643
		644	$PERL = $perl;
558	}	645	}
559		646
560	require Proc::FastSpawn;	647	require Proc::FastSpawn;
561		648
562	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	649	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
…		…
570	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;	657	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;
571	my %env = %ENV;	658	my %env = %ENV;
572	$env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC;	659	$env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC;
573		660
574	my $pid = Proc::FastSpawn::spawn (	661	my $pid = Proc::FastSpawn::spawn (
575	$perl,	662	$PERL,
576	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],	663	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],
577	[map "$_=$env{$_}", keys %env],	664	[map "$_=$env{$_}", keys %env],
578	) or die "unable to spawn AnyEvent::Fork server: $!";	665	) or die "unable to spawn AnyEvent::Fork server: $!";
579		666
580	$self->_new ($fh, $pid)	667	$self->_new ($fh, $pid)
581	}	668	}
582		669
583	=item $pid = $proc->pid	670	=item $pid = $proc->pid
584		671
585	Returns the process id of the process I<iff it is a direct child of the	672	Returns the process id of the process I<iff it is a direct child of the
586	process running AnyEvent::Fork>, and C<undef> otherwise.	673	process running AnyEvent::Fork>, and C<undef> otherwise. As a general
		674	rule (that you cannot rely upon), processes created via C<new_exec>,
		675	L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template> are direct
		676	children, while all other processes are not.
587		677
588	Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and	678	Or in other words, you do not normally have to take care of zombies for
589	L<AnyEvent::Fork::Template> are direct children, and you are responsible	679	processes created via C<new>, but when in doubt, or zombies are a problem,
590	to clean up their zombies when they die.	680	you need to check whether a process is a diretc child by calling this
591		681	method, and possibly creating a child watcher or reap it manually.
592	All other processes are not direct children, and will be cleaned up by
593	AnyEvent::Fork itself.
594		682
595	=cut	683	=cut
596		684
597	sub pid {	685	sub pid {
598	$_[0][PID]	686	$_[0][PID]
599	}	687	}
600		688
601	=item $proc = $proc->eval ($perlcode, @args)	689	=item $proc = $proc->eval ($perlcode, @args)
602		690
603	Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to	691	Evaluates the given C<$perlcode> as ... Perl code, while setting C<@_> to
604	the strings specified by C<@args>, in the "main" package.	692	the strings specified by C<@args>, in the "main" package.
605		693
606	This call is meant to do any custom initialisation that might be required	694	This call is meant to do any custom initialisation that might be required
607	(for example, the C<require> method uses it). It's not supposed to be used	695	(for example, the C<require> method uses it). It's not supposed to be used
608	to completely take over the process, use C<run> for that.	696	to completely take over the process, use C<run> for that.
…		…
729		817
730	Even if not used otherwise, the socket can be a good indicator for the	818	Even if not used otherwise, the socket can be a good indicator for the
731	existence of the process - if the other process exits, you get a readable	819	existence of the process - if the other process exits, you get a readable
732	event on it, because exiting the process closes the socket (if it didn't	820	event on it, because exiting the process closes the socket (if it didn't
733	create any children using fork).	821	create any children using fork).
		822
		823	=over 4
		824
		825	=item Compatibility to L<AnyEvent::Fork::Remote>
		826
		827	If you want to write code that works with both this module and
		828	L<AnyEvent::Fork::Remote>, you need to write your code so that it assumes
		829	there are two file handles for communications, which might not be unix
		830	domain sockets. The C<run> function should start like this:
		831
		832	sub run {
		833	my ($rfh, @args) = @_; # @args is your normal arguments
		834	my $wfh = fileno $rfh ? $rfh : *STDOUT;
		835
		836	# now use $rfh for reading and $wfh for writing
		837	}
		838
		839	This checks whether the passed file handle is, in fact, the process
		840	C<STDIN> handle. If it is, then the function was invoked visa
		841	L<AnyEvent::Fork::Remote>, so STDIN should be used for reading and
		842	C<STDOUT> should be used for writing.
		843
		844	In all other cases, the function was called via this module, and there is
		845	only one file handle that should be sued for reading and writing.
		846
		847	=back
734		848
735	Example: create a template for a process pool, pass a few strings, some	849	Example: create a template for a process pool, pass a few strings, some
736	file handles, then fork, pass one more string, and run some code.	850	file handles, then fork, pass one more string, and run some code.
737		851
738	my $pool = AnyEvent::Fork	852	my $pool = AnyEvent::Fork
…		…
772	$self->_cmd (r => $func);	886	$self->_cmd (r => $func);
773	}	887	}
774		888
775	=back	889	=back
776		890
		891	=head2 EXPERIMENTAL METHODS
		892
		893	These methods might go away completely or change behaviour, at any time.
		894
		895	=over 4
		896
		897	=item $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED
		898
		899	Flushes all commands out to the process and then calls the callback with
		900	the communications socket.
		901
		902	The process object becomes unusable on return from this function - any
		903	further method calls result in undefined behaviour.
		904
		905	The point of this method is to give you a file handle that you can pass
		906	to another process. In that other process, you can call C<new_from_fh
		907	AnyEvent::Fork $fh> to create a new C<AnyEvent::Fork> object from it,
		908	thereby effectively passing a fork object to another process.
		909
		910	=cut
		911
		912	sub to_fh {
		913	my ($self, $cb) = @_;
		914
		915	$self->[CB] = $cb;
		916
		917	unless ($self->[WW]) {
		918	$self->[CB]->($self->[FH]);
		919	@$self = ();
		920	}
		921	}
		922
		923	=item new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED
		924
		925	Takes a file handle originally rceeived by the C<to_fh> method and creates
		926	a new C<AnyEvent:Fork> object. The child process itself will not change in
		927	any way, i.e. it will keep all the modifications done to it before calling
		928	C<to_fh>.
		929
		930	The new object is very much like the original object, except that the
		931	C<pid> method will return C<undef> even if the process is a direct child.
		932
		933	=cut
		934
		935	sub new_from_fh {
		936	my ($class, $fh) = @_;
		937
		938	$class->_new ($fh)
		939	}
		940
		941	=back
		942
777	=head1 PERFORMANCE	943	=head1 PERFORMANCE
778		944
779	Now for some unscientific benchmark numbers (all done on an amd64	945	Now for some unscientific benchmark numbers (all done on an amd64
780	GNU/Linux box). These are intended to give you an idea of the relative	946	GNU/Linux box). These are intended to give you an idea of the relative
781	performance you can expect, they are not meant to be absolute performance	947	performance you can expect, they are not meant to be absolute performance
…		…
787		953
788	2079 new processes per second, using manual socketpair + fork	954	2079 new processes per second, using manual socketpair + fork
789		955
790	Then I did the same thing, but instead of calling fork, I called	956	Then I did the same thing, but instead of calling fork, I called
791	AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the	957	AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the
792	socket form the child to close on exit. This does the same thing as manual	958	socket from the child to close on exit. This does the same thing as manual
793	socket pair + fork, except that what is forked is the template process	959	socket pair + fork, except that what is forked is the template process
794	(2440kB), and the socket needs to be passed to the server at the other end	960	(2440kB), and the socket needs to be passed to the server at the other end
795	of the socket first.	961	of the socket first.
796		962
797	2307 new processes per second, using AnyEvent::Fork->new	963	2307 new processes per second, using AnyEvent::Fork->new
…		…
804	So how can C<< AnyEvent->new >> be faster than a standard fork, even	970	So how can C<< AnyEvent->new >> be faster than a standard fork, even
805	though it uses the same operations, but adds a lot of overhead?	971	though it uses the same operations, but adds a lot of overhead?
806		972
807	The difference is simply the process size: forking the 5MB process takes	973	The difference is simply the process size: forking the 5MB process takes
808	so much longer than forking the 2.5MB template process that the extra	974	so much longer than forking the 2.5MB template process that the extra
809	overhead introduced is canceled out.	975	overhead is canceled out.
810		976
811	If the benchmark process grows, the normal fork becomes even slower:	977	If the benchmark process grows, the normal fork becomes even slower:
812		978
813	1340 new processes, manual fork of a 20MB process	979	1340 new processes, manual fork of a 20MB process
814	731 new processes, manual fork of a 200MB process	980	731 new processes, manual fork of a 200MB process
…		…
874	initialising them, for example, by calling C<init Gtk2> manually.	1040	initialising them, for example, by calling C<init Gtk2> manually.
875		1041
876	=item exiting calls object destructors	1042	=item exiting calls object destructors
877		1043
878	This only applies to users of L<AnyEvent::Fork:Early> and	1044	This only applies to users of L<AnyEvent::Fork:Early> and
879	L<AnyEvent::Fork::Template>, or when initialiasing code creates objects	1045	L<AnyEvent::Fork::Template>, or when initialising code creates objects
880	that reference external resources.	1046	that reference external resources.
881		1047
882	When a process created by AnyEvent::Fork exits, it might do so by calling	1048	When a process created by AnyEvent::Fork exits, it might do so by calling
883	exit, or simply letting perl reach the end of the program. At which point	1049	exit, or simply letting perl reach the end of the program. At which point
884	Perl runs all destructors.	1050	Perl runs all destructors.
…		…
904	to make it so, mostly due to the bloody broken perl that nobody seems to	1070	to make it so, mostly due to the bloody broken perl that nobody seems to
905	care about. The fork emulation is a bad joke - I have yet to see something	1071	care about. The fork emulation is a bad joke - I have yet to see something
906	useful that you can do with it without running into memory corruption	1072	useful that you can do with it without running into memory corruption
907	issues or other braindamage. Hrrrr.	1073	issues or other braindamage. Hrrrr.
908		1074
		1075	Since fork is endlessly broken on win32 perls (it doesn't even remotely
		1076	work within it's documented limits) and quite obviously it's not getting
		1077	improved any time soon, the best way to proceed on windows would be to
		1078	always use C<new_exec> and thus never rely on perl's fork "emulation".
		1079
909	Cygwin perl is not supported at the moment due to some hilarious	1080	Cygwin perl is not supported at the moment due to some hilarious
910	shortcomings of its API - see L<IO::FDPoll> for more details.	1081	shortcomings of its API - see L<IO::FDPoll> for more details. If you never
		1082	use C<send_fh> and always use C<new_exec> to create processes, it should
		1083	work though.
911		1084
912	=head1 SEE ALSO	1085	=head1 SEE ALSO
913		1086
914	L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter),	1087	L<AnyEvent::Fork::Early>, to avoid executing a perl interpreter at all
		1088	(part of this distribution).
		1089
915	L<AnyEvent::Fork::Template> (to create a process by forking the main	1090	L<AnyEvent::Fork::Template>, to create a process by forking the main
916	program at a convenient time).	1091	program at a convenient time (part of this distribution).
917		1092
918	=head1 AUTHOR	1093	L<AnyEvent::Fork::Remote>, for another way to create processes that is
		1094	mostly compatible to this module and modules building on top of it, but
		1095	works better with remote processes.
		1096
		1097	L<AnyEvent::Fork::RPC>, for simple RPC to child processes (on CPAN).
		1098
		1099	L<AnyEvent::Fork::Pool>, for simple worker process pool (on CPAN).
		1100
		1101	=head1 AUTHOR AND CONTACT INFORMATION
919		1102
920	Marc Lehmann <schmorp@schmorp.de>	1103	Marc Lehmann <schmorp@schmorp.de>
921	http://home.schmorp.de/	1104	http://software.schmorp.de/pkg/AnyEvent-Fork
922		1105
923	=cut	1106	=cut
924		1107
925	1	1108	1
926		1109

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Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.42 by root, Mon Apr 8 05:44:23 2013 UTC vs. Revision 1.60 by root, Wed Sep 25 11:05:30 2013 UTC

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Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.42 by root, Mon Apr 8 05:44:23 2013 UTC vs.
Revision 1.60 by root, Wed Sep 25 11:05:30 2013 UTC