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

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.44 by root, Thu Apr 18 10:49:59 2013 UTC vs.
Revision 1.53 by root, Fri Apr 26 15:44:44 2013 UTC

…		…
38		38
39	If you need some form of RPC, you could use the L<AnyEvent::Fork::RPC>	39	If you need some form of RPC, you could use the L<AnyEvent::Fork::RPC>
40	companion module, which adds simple RPC/job queueing to a process created	40	companion module, which adds simple RPC/job queueing to a process created
41	by this module.	41	by this module.
42		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
43	Or you can implement it yourself in whatever way you like, use some	47	Or you can implement it yourself in whatever way you like: use some
44	message-passing module such as L<AnyEvent::MP>, some pipe such as	48	message-passing module such as L<AnyEvent::MP>, some pipe such as
45	L<AnyEvent::ZeroMQ>, use L<AnyEvent::Handle> on both sides to send	49	L<AnyEvent::ZeroMQ>, use L<AnyEvent::Handle> on both sides to send
46	e.g. JSON or Storable messages, and so on.	50	e.g. JSON or Storable messages, and so on.
47		51
48	=head2 COMPARISON TO OTHER MODULES	52	=head2 COMPARISON TO OTHER MODULES
…		…
250	->send_arg ("/bin/echo", "hi")	254	->send_arg ("/bin/echo", "hi")
251	->run ("run", my $cv = AE::cv);	255	->run ("run", my $cv = AE::cv);
252		256
253	my $stderr = $cv->recv;	257	my $stderr = $cv->recv;
254		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
255	=head1 CONCEPTS	328	=head1 CONCEPTS
256		329
257	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
258	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".
259		336
260	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
261	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,
262	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
263	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
…		…
373	use AnyEvent;	450	use AnyEvent;
374	use AnyEvent::Util ();	451	use AnyEvent::Util ();
375		452
376	use IO::FDPass;	453	use IO::FDPass;
377		454
378	our $VERSION = 0.6;	455	our $VERSION = '1.0';
379		456
380	# the early fork template process	457	# the early fork template process
381	our $EARLY;	458	our $EARLY;
382		459
383	# the empty template process	460	# the empty template process
…		…
431	# send string	508	# send string
432	my $len = syswrite $self->[FH], $self->[QUEUE][0];	509	my $len = syswrite $self->[FH], $self->[QUEUE][0];
433		510
434	unless ($len) {	511	unless ($len) {
435	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;	512	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;
436	undef $self->[3];	513	undef $self->[WW];
437	die "AnyEvent::Fork: command write failure: $!";	514	die "AnyEvent::Fork: command write failure: $!";
438	}	515	}
439		516
440	substr $self->[QUEUE][0], 0, $len, "";	517	substr $self->[QUEUE][0], 0, $len, "";
441	shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0];	518	shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0];
…		…
444		521
445	# everything written	522	# everything written
446	undef $self->[WW];	523	undef $self->[WW];
447		524
448	# invoke run callback, if any	525	# invoke run callback, if any
		526	if ($self->[CB]) {
449	$self->[CB]->($self->[FH]) if $self->[CB];	527	$self->[CB]->($self->[FH]);
		528	@$self = ();
		529	}
450	};	530	};
451		531
452	() # make sure we don't leak the watcher	532	() # make sure we don't leak the watcher
453	}	533	}
454		534
…		…
769	$self->_cmd (r => $func);	849	$self->_cmd (r => $func);
770	}	850	}
771		851
772	=back	852	=back
773		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)
		968	}
		969
		970	=back
		971
774	=head1 PERFORMANCE	972	=head1 PERFORMANCE
775		973
776	Now for some unscientific benchmark numbers (all done on an amd64	974	Now for some unscientific benchmark numbers (all done on an amd64
777	GNU/Linux box). These are intended to give you an idea of the relative	975	GNU/Linux box). These are intended to give you an idea of the relative
778	performance you can expect, they are not meant to be absolute performance	976	performance you can expect, they are not meant to be absolute performance
…		…
784		982
785	2079 new processes per second, using manual socketpair + fork	983	2079 new processes per second, using manual socketpair + fork
786		984
787	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
788	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
789	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
790	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
791	(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
792	of the socket first.	990	of the socket first.
793		991
794	2307 new processes per second, using AnyEvent::Fork->new	992	2307 new processes per second, using AnyEvent::Fork->new
…		…
901	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
902	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
903	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
904	issues or other braindamage. Hrrrr.	1102	issues or other braindamage. Hrrrr.
905		1103
		1104	Since fork is endlessly broken on win32 perls (it doesn't even remotely
		1105	work within it's documented limits) and quite obviously it's not getting
		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
906	Cygwin perl is not supported at the moment due to some hilarious	1109	Cygwin perl is not supported at the moment due to some hilarious
907	shortcomings of its API - see L<IO::FDPoll> for more details.	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.
908		1113
909	=head1 SEE ALSO	1114	=head1 SEE ALSO
910		1115
911	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
912	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
913	program at a convenient time), L<AnyEvent::Fork::RPC> (for simple RPC to	1120	program at a convenient time (part of this distribution).
914	child processes).	1121
		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).
915		1125
916	=head1 AUTHOR AND CONTACT INFORMATION	1126	=head1 AUTHOR AND CONTACT INFORMATION
917		1127
918	Marc Lehmann <schmorp@schmorp.de>	1128	Marc Lehmann <schmorp@schmorp.de>
919	http://software.schmorp.de/pkg/AnyEvent-Fork	1129	http://software.schmorp.de/pkg/AnyEvent-Fork

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Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.44 by root, Thu Apr 18 10:49:59 2013 UTC vs. Revision 1.53 by root, Fri Apr 26 15:44:44 2013 UTC

Diff Legend

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.44 by root, Thu Apr 18 10:49:59 2013 UTC vs.
Revision 1.53 by root, Fri Apr 26 15:44:44 2013 UTC