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

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.41 by root, Mon Apr 8 03:20:53 2013 UTC vs.
Revision 1.63 by root, Wed Nov 26 13:36:18 2014 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>
49	or L<AnyEvent::Subprocess>. There are modules that implement their own	56	or L<AnyEvent::Subprocess>. There are modules that implement their own
50	process management, such as L<AnyEvent::DBI>.	57	process management, such as L<AnyEvent::DBI>.
51		58
52	The problems that all these modules try to solve are real, however, none	59	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	60	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	61	memory sharing, efficiency or not being able to use event processing, GUI
55	similar modules in the processes they create.	62	toolkits or similar modules in the processes they create.
56		63
57	This module doesn't try to replace any of them - instead it tries to solve	64	This module doesn't try to replace any of them - instead it tries to solve
58	the problem of creating processes with a minimum of fuss and overhead (and	65	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,	66	also luxury). Ideally, most of these would use AnyEvent::Fork internally,
60	except they were written before AnyEvent:Fork was available, so obviously	67	except they were written before AnyEvent:Fork was available, so obviously
…		…
82		89
83	=item Forking usually creates a copy-on-write copy of the parent	90	=item Forking usually creates a copy-on-write copy of the parent
84	process.	91	process.
85		92
86	For example, modules or data files that are loaded will not use additional	93	For example, modules or data files that are loaded will not use additional
87	memory after a fork. When exec'ing a new process, modules and data files	94	memory after a fork. Exec'ing a new process, in contrast, means modules
88	might need to be loaded again, at extra CPU and memory cost. But when	95	and data files might need to be loaded again, at extra CPU and memory
89	forking, literally all data structures are copied - if the program frees	96	cost.
		97
		98	But when forking, you still create a copy of your data structures - if
90	them and replaces them by new data, the child processes will retain the	99	the program frees them and replaces them by new data, the child processes
91	old version even if it isn't used, which can suddenly and unexpectedly	100	will retain the old version even if it isn't used, which can suddenly and
92	increase memory usage when freeing memory.	101	unexpectedly increase memory usage when freeing memory.
93		102
		103	For example, L<Gtk2::CV> is an image viewer optimised for large
		104	directories (millions of pictures). It also forks subprocesses for
		105	thumbnail generation, which inherit the data structure that stores all
		106	file information. If the user changes the directory, it gets freed in
		107	the main process, leaving a copy in the thumbnailer processes. This can
		108	lead to many times the memory usage that would actually be required. The
		109	solution is to fork early (and being unable to dynamically generate more
		110	subprocesses or do this from a module)... or to use L<AnyEvent:Fork>.
		111
94	The trade-off is between more sharing with fork (which can be good or	112	There is a trade-off between more sharing with fork (which can be good or
95	bad), and no sharing with exec.	113	bad), and no sharing with exec.
96		114
97	This module allows the main program to do a controlled fork, and allows	115	This module allows the main program to do a controlled fork, and allows
98	modules to exec processes safely at any time. When creating a custom	116	modules to exec processes safely at any time. When creating a custom
99	process pool you can take advantage of data sharing via fork without	117	process pool you can take advantage of data sharing via fork without
…		…
104	shared and what isn't, at all times.	122	shared and what isn't, at all times.
105		123
106	=item Exec'ing a new perl process might be difficult.	124	=item Exec'ing a new perl process might be difficult.
107		125
108	For example, it is not easy to find the correct path to the perl	126	For example, it is not easy to find the correct path to the perl
109	interpreter - C<$^X> might not be a perl interpreter at all.	127	interpreter - C<$^X> might not be a perl interpreter at all. Worse, there
		128	might not even be a perl binary installed on the system.
110		129
111	This module tries hard to identify the correct path to the perl	130	This module tries hard to identify the correct path to the perl
112	interpreter. With a cooperative main program, exec'ing the interpreter	131	interpreter. With a cooperative main program, exec'ing the interpreter
113	might not even be necessary, but even without help from the main program,	132	might not even be necessary, but even without help from the main program,
114	it will still work when used from a module.	133	it will still work when used from a module.
…		…
120	and modules are no longer loadable because they refer to a different	139	and modules are no longer loadable because they refer to a different
121	perl version, or parts of a distribution are newer than the ones already	140	perl version, or parts of a distribution are newer than the ones already
122	loaded.	141	loaded.
123		142
124	This module supports creating pre-initialised perl processes to be used as	143	This module supports creating pre-initialised perl processes to be used as
125	a template for new processes.	144	a template for new processes at a later time, e.g. for use in a process
		145	pool.
126		146
127	=item Forking might be impossible when a program is running.	147	=item Forking might be impossible when a program is running.
128		148
129	For example, POSIX makes it almost impossible to fork from a	149	For example, POSIX makes it almost impossible to fork from a
130	multi-threaded program while doing anything useful in the child - in	150	multi-threaded program while doing anything useful in the child - in
131	fact, if your perl program uses POSIX threads (even indirectly via	151	fact, if your perl program uses POSIX threads (even indirectly via
132	e.g. L<IO::AIO> or L<threads>), you cannot call fork on the perl level	152	e.g. L<IO::AIO> or L<threads>), you cannot call fork on the perl level
133	anymore without risking corruption issues on a number of operating	153	anymore without risking memory corruption or worse on a number of
134	systems.	154	operating systems.
135		155
136	This module can safely fork helper processes at any time, by calling	156	This module can safely fork helper processes at any time, by calling
137	fork+exec in C, in a POSIX-compatible way (via L<Proc::FastSpawn>).	157	fork+exec in C, in a POSIX-compatible way (via L<Proc::FastSpawn>).
138		158
139	=item Parallel processing with fork might be inconvenient or difficult	159	=item Parallel processing with fork might be inconvenient or difficult
…		…
221	}	241	}
222	}	242	}
223		243
224	=head2 use AnyEvent::Fork as a faster fork+exec	244	=head2 use AnyEvent::Fork as a faster fork+exec
225		245
226	This runs C</bin/echo hi>, with stdandard output redirected to /tmp/log	246	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	247	and standard error redirected to the communications socket. It is usually
228	faster than fork+exec, but still lets you prepare the environment.	248	faster than fork+exec, but still lets you prepare the environment.
229		249
230	open my $output, ">/tmp/log" or die "$!";	250	open my $output, ">/tmp/log" or die "$!";
231		251
…		…
247	->send_arg ("/bin/echo", "hi")	267	->send_arg ("/bin/echo", "hi")
248	->run ("run", my $cv = AE::cv);	268	->run ("run", my $cv = AE::cv);
249		269
250	my $stderr = $cv->recv;	270	my $stderr = $cv->recv;
251		271
		272	=head2 For stingy users: put the worker code into a C<DATA> section.
		273
		274	When you want to be stingy with files, you can put your code into the
		275	C<DATA> section of your module (or program):
		276
		277	use AnyEvent::Fork;
		278
		279	AnyEvent::Fork
		280	->new
		281	->eval (do { local $/; <DATA> })
		282	->run ("doit", sub { ... });
		283
		284	__DATA__
		285
		286	sub doit {
		287	... do something!
		288	}
		289
		290	=head2 For stingy standalone programs: do not rely on external files at
		291	all.
		292
		293	For single-file scripts it can be inconvenient to rely on external
		294	files - even when using a C<DATA> section, you still need to C<exec> an
		295	external perl interpreter, which might not be available when using
		296	L<App::Staticperl>, L<Urlader> or L<PAR::Packer> for example.
		297
		298	Two modules help here - L<AnyEvent::Fork::Early> forks a template process
		299	for all further calls to C<new_exec>, and L<AnyEvent::Fork::Template>
		300	forks the main program as a template process.
		301
		302	Here is how your main program should look like:
		303
		304	#! perl
		305
		306	# optional, as the very first thing.
		307	# in case modules want to create their own processes.
		308	use AnyEvent::Fork::Early;
		309
		310	# next, load all modules you need in your template process
		311	use Example::My::Module
		312	use Example::Whatever;
		313
		314	# next, put your run function definition and anything else you
		315	# need, but do not use code outside of BEGIN blocks.
		316	sub worker_run {
		317	my ($fh, @args) = @_;
		318	...
		319	}
		320
		321	# now preserve everything so far as AnyEvent::Fork object
		322	# in $TEMPLATE.
		323	use AnyEvent::Fork::Template;
		324
		325	# do not put code outside of BEGIN blocks until here
		326
		327	# now use the $TEMPLATE process in any way you like
		328
		329	# for example: create 10 worker processes
		330	my @worker;
		331	my $cv = AE::cv;
		332	for (1..10) {
		333	$cv->begin;
		334	$TEMPLATE->fork->send_arg ($_)->run ("worker_run", sub {
		335	push @worker, shift;
		336	$cv->end;
		337	});
		338	}
		339	$cv->recv;
		340
252	=head1 CONCEPTS	341	=head1 CONCEPTS
253		342
254	This module can create new processes either by executing a new perl	343	This module can create new processes either by executing a new perl
255	process, or by forking from an existing "template" process.	344	process, or by forking from an existing "template" process.
		345
		346	All these processes are called "child processes" (whether they are direct
		347	children or not), while the process that manages them is called the
		348	"parent process".
256		349
257	Each such process comes with its own file handle that can be used to	350	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,	351	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	352	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	353	load modules, fork new processes, send file handles to it, and execute
…		…
370	use AnyEvent;	463	use AnyEvent;
371	use AnyEvent::Util ();	464	use AnyEvent::Util ();
372		465
373	use IO::FDPass;	466	use IO::FDPass;
374		467
375	our $VERSION = 0.6;	468	our $VERSION = 1.2;
376
377	=over 4
378
379	=back
380
381	=cut
382		469
383	# the early fork template process	470	# the early fork template process
384	our $EARLY;	471	our $EARLY;
385		472
386	# the empty template process	473	# the empty template process
387	our $TEMPLATE;	474	our $TEMPLATE;
		475
		476	sub QUEUE() { 0 }
		477	sub FH() { 1 }
		478	sub WW() { 2 }
		479	sub PID() { 3 }
		480	sub CB() { 4 }
		481
		482	sub _new {
		483	my ($self, $fh, $pid) = @_;
		484
		485	AnyEvent::Util::fh_nonblocking $fh, 1;
		486
		487	$self = bless [
		488	[], # write queue - strings or fd's
		489	$fh,
		490	undef, # AE watcher
		491	$pid,
		492	], $self;
		493
		494	$self
		495	}
388		496
389	sub _cmd {	497	sub _cmd {
390	my $self = shift;	498	my $self = shift;
391		499
392	# ideally, we would want to use "a (w/a)*" as format string, but perl	500	# ideally, we would want to use "a (w/a)*" as format string, but perl
393	# versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack	501	# versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack
394	# it.	502	# it.
395	push @{ $self->[2] }, pack "a L/a*", $_[0], $_[1];	503	push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1];
396		504
397	$self->[3] \|\|= AE::io $self->[1], 1, sub {	505	$self->[WW] \|\|= AE::io $self->[FH], 1, sub {
398	do {	506	do {
399	# send the next "thing" in the queue - either a reference to an fh,	507	# send the next "thing" in the queue - either a reference to an fh,
400	# or a plain string.	508	# or a plain string.
401		509
402	if (ref $self->[2][0]) {	510	if (ref $self->[QUEUE][0]) {
403	# send fh	511	# send fh
404	unless (IO::FDPass::send fileno $self->[1], fileno ${ $self->[2][0] }) {	512	unless (IO::FDPass::send fileno $self->[FH], fileno ${ $self->[QUEUE][0] }) {
405	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;	513	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;
406	undef $self->[3];	514	undef $self->[WW];
407	die "AnyEvent::Fork: file descriptor send failure: $!";	515	die "AnyEvent::Fork: file descriptor send failure: $!";
408	}	516	}
409		517
410	shift @{ $self->[2] };	518	shift @{ $self->[QUEUE] };
411		519
412	} else {	520	} else {
413	# send string	521	# send string
414	my $len = syswrite $self->[1], $self->[2][0];	522	my $len = syswrite $self->[FH], $self->[QUEUE][0];
415		523
416	unless ($len) {	524	unless ($len) {
417	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;	525	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;
418	undef $self->[3];	526	undef $self->[WW];
419	die "AnyEvent::Fork: command write failure: $!";	527	die "AnyEvent::Fork: command write failure: $!";
420	}	528	}
421		529
422	substr $self->[2][0], 0, $len, "";	530	substr $self->[QUEUE][0], 0, $len, "";
423	shift @{ $self->[2] } unless length $self->[2][0];	531	shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0];
424	}	532	}
425	} while @{ $self->[2] };	533	} while @{ $self->[QUEUE] };
426		534
427	# everything written	535	# everything written
428	undef $self->[3];	536	undef $self->[WW];
429		537
430	# invoke run callback, if any	538	# invoke run callback, if any
431	$self->[4]->($self->[1]) if $self->[4];	539	if ($self->[CB]) {
		540	$self->[CB]->($self->[FH]);
		541	@$self = ();
		542	}
432	};	543	};
433		544
434	() # make sure we don't leak the watcher	545	() # make sure we don't leak the watcher
435	}
436
437	sub _new {
438	my ($self, $fh, $pid) = @_;
439
440	AnyEvent::Util::fh_nonblocking $fh, 1;
441
442	$self = bless [
443	$pid,
444	$fh,
445	[], # write queue - strings or fd's
446	undef, # AE watcher
447	], $self;
448
449	$self
450	}	546	}
451		547
452	# fork template from current process, used by AnyEvent::Fork::Early/Template	548	# fork template from current process, used by AnyEvent::Fork::Early/Template
453	sub _new_fork {	549	sub _new_fork {
454	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	550	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
…		…
522		618
523	You should use C<new> whenever possible, except when having a template	619	You should use C<new> whenever possible, except when having a template
524	process around is unacceptable.	620	process around is unacceptable.
525		621
526	The path to the perl interpreter is divined using various methods - first	622	The path to the perl interpreter is divined using various methods - first
527	C<$^X> is investigated to see if the path ends with something that sounds	623	C<$^X> is investigated to see if the path ends with something that looks
528	as if it were the perl interpreter. Failing this, the module falls back to	624	as if it were the perl interpreter. Failing this, the module falls back to
529	using C<$Config::Config{perlpath}>.	625	using C<$Config::Config{perlpath}>.
530		626
		627	The path to perl can also be overriden by setting the global variable
		628	C<$AnyEvent::Fork::PERL> - it's value will be used for all subsequent
		629	invocations.
		630
531	=cut	631	=cut
		632
		633	our $PERL;
532		634
533	sub new_exec {	635	sub new_exec {
534	my ($self) = @_;	636	my ($self) = @_;
535		637
536	return $EARLY->fork	638	return $EARLY->fork
537	if $EARLY;	639	if $EARLY;
538		640
		641	unless (defined $PERL) {
539	# first find path of perl	642	# first find path of perl
540	my $perl = $;	643	my $perl = $^X;
541		644
542	# first we try $^X, but the path must be absolute (always on win32), and end in sth.	645	# first we try $^X, but the path must be absolute (always on win32), and end in sth.
543	# that looks like perl. this obviously only works for posix and win32	646	# that looks like perl. this obviously only works for posix and win32
544	unless (	647	unless (
545	($^O eq "MSWin32" \|\| $perl =~ m%^/%)	648	($^O eq "MSWin32" \|\| $perl =~ m%^/%)
546	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i	649	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i
547	) {	650	) {
548	# if it doesn't look perlish enough, try Config	651	# if it doesn't look perlish enough, try Config
549	require Config;	652	require Config;
550	$perl = $Config::Config{perlpath};	653	$perl = $Config::Config{perlpath};
551	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;	654	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;
		655	}
		656
		657	$PERL = $perl;
552	}	658	}
553		659
554	require Proc::FastSpawn;	660	require Proc::FastSpawn;
555		661
556	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	662	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
…		…
564	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;	670	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;
565	my %env = %ENV;	671	my %env = %ENV;
566	$env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC;	672	$env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC;
567		673
568	my $pid = Proc::FastSpawn::spawn (	674	my $pid = Proc::FastSpawn::spawn (
569	$perl,	675	$PERL,
570	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],	676	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],
571	[map "$_=$env{$_}", keys %env],	677	[map "$_=$env{$_}", keys %env],
572	) or die "unable to spawn AnyEvent::Fork server: $!";	678	) or die "unable to spawn AnyEvent::Fork server: $!";
573		679
574	$self->_new ($fh, $pid)	680	$self->_new ($fh, $pid)
575	}	681	}
576		682
577	=item $pid = $proc->pid	683	=item $pid = $proc->pid
578		684
579	Returns the process id of the process I<iff it is a direct child of the	685	Returns the process id of the process I<iff it is a direct child of the
580	process running AnyEvent::Fork>, and C<undef> otherwise.	686	process running AnyEvent::Fork>, and C<undef> otherwise. As a general
		687	rule (that you cannot rely upon), processes created via C<new_exec>,
		688	L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template> are direct
		689	children, while all other processes are not.
581		690
582	Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and	691	Or in other words, you do not normally have to take care of zombies for
583	L<AnyEvent::Fork::Template> are direct children, and you are responsible	692	processes created via C<new>, but when in doubt, or zombies are a problem,
584	to clean up their zombies when they die.	693	you need to check whether a process is a diretc child by calling this
585		694	method, and possibly creating a child watcher or reap it manually.
586	All other processes are not direct children, and will be cleaned up by
587	AnyEvent::Fork itself.
588		695
589	=cut	696	=cut
590		697
591	sub pid {	698	sub pid {
592	$_[0][0]	699	$_[0][PID]
593	}	700	}
594		701
595	=item $proc = $proc->eval ($perlcode, @args)	702	=item $proc = $proc->eval ($perlcode, @args)
596		703
597	Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to	704	Evaluates the given C<$perlcode> as ... Perl code, while setting C<@_> to
598	the strings specified by C<@args>, in the "main" package.	705	the strings specified by C<@args>, in the "main" package.
599		706
600	This call is meant to do any custom initialisation that might be required	707	This call is meant to do any custom initialisation that might be required
601	(for example, the C<require> method uses it). It's not supposed to be used	708	(for example, the C<require> method uses it). It's not supposed to be used
602	to completely take over the process, use C<run> for that.	709	to completely take over the process, use C<run> for that.
…		…
664	sub send_fh {	771	sub send_fh {
665	my ($self, @fh) = @_;	772	my ($self, @fh) = @_;
666		773
667	for my $fh (@fh) {	774	for my $fh (@fh) {
668	$self->_cmd ("h");	775	$self->_cmd ("h");
669	push @{ $self->[2] }, \$fh;	776	push @{ $self->[QUEUE] }, \$fh;
670	}	777	}
671		778
672	$self	779	$self
673	}	780	}
674		781
…		…
723		830
724	Even if not used otherwise, the socket can be a good indicator for the	831	Even if not used otherwise, the socket can be a good indicator for the
725	existence of the process - if the other process exits, you get a readable	832	existence of the process - if the other process exits, you get a readable
726	event on it, because exiting the process closes the socket (if it didn't	833	event on it, because exiting the process closes the socket (if it didn't
727	create any children using fork).	834	create any children using fork).
		835
		836	=over 4
		837
		838	=item Compatibility to L<AnyEvent::Fork::Remote>
		839
		840	If you want to write code that works with both this module and
		841	L<AnyEvent::Fork::Remote>, you need to write your code so that it assumes
		842	there are two file handles for communications, which might not be unix
		843	domain sockets. The C<run> function should start like this:
		844
		845	sub run {
		846	my ($rfh, @args) = @_; # @args is your normal arguments
		847	my $wfh = fileno $rfh ? $rfh : *STDOUT;
		848
		849	# now use $rfh for reading and $wfh for writing
		850	}
		851
		852	This checks whether the passed file handle is, in fact, the process
		853	C<STDIN> handle. If it is, then the function was invoked visa
		854	L<AnyEvent::Fork::Remote>, so STDIN should be used for reading and
		855	C<STDOUT> should be used for writing.
		856
		857	In all other cases, the function was called via this module, and there is
		858	only one file handle that should be sued for reading and writing.
		859
		860	=back
728		861
729	Example: create a template for a process pool, pass a few strings, some	862	Example: create a template for a process pool, pass a few strings, some
730	file handles, then fork, pass one more string, and run some code.	863	file handles, then fork, pass one more string, and run some code.
731		864
732	my $pool = AnyEvent::Fork	865	my $pool = AnyEvent::Fork
…		…
760	=cut	893	=cut
761		894
762	sub run {	895	sub run {
763	my ($self, $func, $cb) = @_;	896	my ($self, $func, $cb) = @_;
764		897
765	$self->[4] = $cb;	898	$self->[CB] = $cb;
766	$self->_cmd (r => $func);	899	$self->_cmd (r => $func);
		900	}
		901
		902	=back
		903
		904	=head2 EXPERIMENTAL METHODS
		905
		906	These methods might go away completely or change behaviour, at any time.
		907
		908	=over 4
		909
		910	=item $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED
		911
		912	Flushes all commands out to the process and then calls the callback with
		913	the communications socket.
		914
		915	The process object becomes unusable on return from this function - any
		916	further method calls result in undefined behaviour.
		917
		918	The point of this method is to give you a file handle that you can pass
		919	to another process. In that other process, you can call C<new_from_fh
		920	AnyEvent::Fork $fh> to create a new C<AnyEvent::Fork> object from it,
		921	thereby effectively passing a fork object to another process.
		922
		923	=cut
		924
		925	sub to_fh {
		926	my ($self, $cb) = @_;
		927
		928	$self->[CB] = $cb;
		929
		930	unless ($self->[WW]) {
		931	$self->[CB]->($self->[FH]);
		932	@$self = ();
		933	}
		934	}
		935
		936	=item new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED
		937
		938	Takes a file handle originally rceeived by the C<to_fh> method and creates
		939	a new C<AnyEvent:Fork> object. The child process itself will not change in
		940	any way, i.e. it will keep all the modifications done to it before calling
		941	C<to_fh>.
		942
		943	The new object is very much like the original object, except that the
		944	C<pid> method will return C<undef> even if the process is a direct child.
		945
		946	=cut
		947
		948	sub new_from_fh {
		949	my ($class, $fh) = @_;
		950
		951	$class->_new ($fh)
767	}	952	}
768		953
769	=back	954	=back
770		955
771	=head1 PERFORMANCE	956	=head1 PERFORMANCE
…		…
781		966
782	2079 new processes per second, using manual socketpair + fork	967	2079 new processes per second, using manual socketpair + fork
783		968
784	Then I did the same thing, but instead of calling fork, I called	969	Then I did the same thing, but instead of calling fork, I called
785	AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the	970	AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the
786	socket form the child to close on exit. This does the same thing as manual	971	socket from the child to close on exit. This does the same thing as manual
787	socket pair + fork, except that what is forked is the template process	972	socket pair + fork, except that what is forked is the template process
788	(2440kB), and the socket needs to be passed to the server at the other end	973	(2440kB), and the socket needs to be passed to the server at the other end
789	of the socket first.	974	of the socket first.
790		975
791	2307 new processes per second, using AnyEvent::Fork->new	976	2307 new processes per second, using AnyEvent::Fork->new
…		…
798	So how can C<< AnyEvent->new >> be faster than a standard fork, even	983	So how can C<< AnyEvent->new >> be faster than a standard fork, even
799	though it uses the same operations, but adds a lot of overhead?	984	though it uses the same operations, but adds a lot of overhead?
800		985
801	The difference is simply the process size: forking the 5MB process takes	986	The difference is simply the process size: forking the 5MB process takes
802	so much longer than forking the 2.5MB template process that the extra	987	so much longer than forking the 2.5MB template process that the extra
803	overhead introduced is canceled out.	988	overhead is canceled out.
804		989
805	If the benchmark process grows, the normal fork becomes even slower:	990	If the benchmark process grows, the normal fork becomes even slower:
806		991
807	1340 new processes, manual fork of a 20MB process	992	1340 new processes, manual fork of a 20MB process
808	731 new processes, manual fork of a 200MB process	993	731 new processes, manual fork of a 200MB process
…		…
868	initialising them, for example, by calling C<init Gtk2> manually.	1053	initialising them, for example, by calling C<init Gtk2> manually.
869		1054
870	=item exiting calls object destructors	1055	=item exiting calls object destructors
871		1056
872	This only applies to users of L<AnyEvent::Fork:Early> and	1057	This only applies to users of L<AnyEvent::Fork:Early> and
873	L<AnyEvent::Fork::Template>, or when initialiasing code creates objects	1058	L<AnyEvent::Fork::Template>, or when initialising code creates objects
874	that reference external resources.	1059	that reference external resources.
875		1060
876	When a process created by AnyEvent::Fork exits, it might do so by calling	1061	When a process created by AnyEvent::Fork exits, it might do so by calling
877	exit, or simply letting perl reach the end of the program. At which point	1062	exit, or simply letting perl reach the end of the program. At which point
878	Perl runs all destructors.	1063	Perl runs all destructors.
…		…
898	to make it so, mostly due to the bloody broken perl that nobody seems to	1083	to make it so, mostly due to the bloody broken perl that nobody seems to
899	care about. The fork emulation is a bad joke - I have yet to see something	1084	care about. The fork emulation is a bad joke - I have yet to see something
900	useful that you can do with it without running into memory corruption	1085	useful that you can do with it without running into memory corruption
901	issues or other braindamage. Hrrrr.	1086	issues or other braindamage. Hrrrr.
902		1087
		1088	Since fork is endlessly broken on win32 perls (it doesn't even remotely
		1089	work within it's documented limits) and quite obviously it's not getting
		1090	improved any time soon, the best way to proceed on windows would be to
		1091	always use C<new_exec> and thus never rely on perl's fork "emulation".
		1092
903	Cygwin perl is not supported at the moment due to some hilarious	1093	Cygwin perl is not supported at the moment due to some hilarious
904	shortcomings of its API - see L<IO::FDPoll> for more details.	1094	shortcomings of its API - see L<IO::FDPoll> for more details. If you never
		1095	use C<send_fh> and always use C<new_exec> to create processes, it should
		1096	work though.
		1097
		1098	=head1 USING AnyEvent::Fork IN SUBPROCESSES
		1099
		1100	AnyEvent::Fork itself cannot generally be used in subprocesses. As long as
		1101	only one process ever forks new processes, sharing the template processes
		1102	is possible (you could use a pipe as a lock by writing a byte into it to
		1103	unlock, and reading the byte to lock for example)
		1104
		1105	To make concurrent calls possible after fork, you should get rid of the
		1106	template and early fork processes. AnyEvent::Fork will create a new
		1107	template process as needed.
		1108
		1109	undef $AnyEvent::Fork::EARLY;
		1110	undef $AnyEvent::Fork::TEMPLATE;
		1111
		1112	It doesn't matter whether you get rid of them in the parent or child after
		1113	a fork.
905		1114
906	=head1 SEE ALSO	1115	=head1 SEE ALSO
907		1116
908	L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter),	1117	L<AnyEvent::Fork::Early>, to avoid executing a perl interpreter at all
		1118	(part of this distribution).
		1119
909	L<AnyEvent::Fork::Template> (to create a process by forking the main	1120	L<AnyEvent::Fork::Template>, to create a process by forking the main
910	program at a convenient time).	1121	program at a convenient time (part of this distribution).
911		1122
912	=head1 AUTHOR	1123	L<AnyEvent::Fork::Remote>, for another way to create processes that is
		1124	mostly compatible to this module and modules building on top of it, but
		1125	works better with remote processes.
		1126
		1127	L<AnyEvent::Fork::RPC>, for simple RPC to child processes (on CPAN).
		1128
		1129	L<AnyEvent::Fork::Pool>, for simple worker process pool (on CPAN).
		1130
		1131	=head1 AUTHOR AND CONTACT INFORMATION
913		1132
914	Marc Lehmann <schmorp@schmorp.de>	1133	Marc Lehmann <schmorp@schmorp.de>
915	http://home.schmorp.de/	1134	http://software.schmorp.de/pkg/AnyEvent-Fork
916		1135
917	=cut	1136	=cut
918		1137
919	1	1138	1
920		1139

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Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.41 by root, Mon Apr 8 03:20:53 2013 UTC vs. Revision 1.63 by root, Wed Nov 26 13:36:18 2014 UTC

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Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.41 by root, Mon Apr 8 03:20:53 2013 UTC vs.
Revision 1.63 by root, Wed Nov 26 13:36:18 2014 UTC