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

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.39 by root, Sat Apr 6 22:39:37 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
232	AnyEvent::Fork	252	AnyEvent::Fork
233	->new	253	->new
234	->eval ('	254	->eval ('
		255	# compile a helper function for later use
235	sub run {	256	sub run {
236	my ($fh, $output, @cmd) = @_;	257	my ($fh, $output, @cmd) = @_;
237		258
238	# perl will clear close-on-exec on STDOUT/STDERR	259	# perl will clear close-on-exec on STDOUT/STDERR
239	open STDOUT, ">&", $output or die;	260	open STDOUT, ">&", $output or die;
…		…
246	->send_arg ("/bin/echo", "hi")	267	->send_arg ("/bin/echo", "hi")
247	->run ("run", my $cv = AE::cv);	268	->run ("run", my $cv = AE::cv);
248		269
249	my $stderr = $cv->recv;	270	my $stderr = $cv->recv;
250		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
251	=head1 CONCEPTS	341	=head1 CONCEPTS
252		342
253	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
254	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".
255		349
256	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
257	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,
258	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
259	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
…		…
369	use AnyEvent;	463	use AnyEvent;
370	use AnyEvent::Util ();	464	use AnyEvent::Util ();
371		465
372	use IO::FDPass;	466	use IO::FDPass;
373		467
374	our $VERSION = 0.5;	468	our $VERSION = 1.2;
375
376	our $PERL; # the path to the perl interpreter, deduces with various forms of magic
377
378	=over 4
379
380	=back
381
382	=cut
383		469
384	# the early fork template process	470	# the early fork template process
385	our $EARLY;	471	our $EARLY;
386		472
387	# the empty template process	473	# the empty template process
388	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	}
389		496
390	sub _cmd {	497	sub _cmd {
391	my $self = shift;	498	my $self = shift;
392		499
393	# 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
394	# 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
395	# it.	502	# it.
396	push @{ $self->[2] }, pack "a L/a*", $_[0], $_[1];	503	push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1];
397		504
398	$self->[3] \|\|= AE::io $self->[1], 1, sub {	505	$self->[WW] \|\|= AE::io $self->[FH], 1, sub {
399	do {	506	do {
400	# 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,
401	# or a plain string.	508	# or a plain string.
402		509
403	if (ref $self->[2][0]) {	510	if (ref $self->[QUEUE][0]) {
404	# send fh	511	# send fh
405	unless (IO::FDPass::send fileno $self->[1], fileno ${ $self->[2][0] }) {	512	unless (IO::FDPass::send fileno $self->[FH], fileno ${ $self->[QUEUE][0] }) {
406	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;	513	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;
407	undef $self->[3];	514	undef $self->[WW];
408	die "AnyEvent::Fork: file descriptor send failure: $!";	515	die "AnyEvent::Fork: file descriptor send failure: $!";
409	}	516	}
410		517
411	shift @{ $self->[2] };	518	shift @{ $self->[QUEUE] };
412		519
413	} else {	520	} else {
414	# send string	521	# send string
415	my $len = syswrite $self->[1], $self->[2][0];	522	my $len = syswrite $self->[FH], $self->[QUEUE][0];
416		523
417	unless ($len) {	524	unless ($len) {
418	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;	525	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;
419	undef $self->[3];	526	undef $self->[WW];
420	die "AnyEvent::Fork: command write failure: $!";	527	die "AnyEvent::Fork: command write failure: $!";
421	}	528	}
422		529
423	substr $self->[2][0], 0, $len, "";	530	substr $self->[QUEUE][0], 0, $len, "";
424	shift @{ $self->[2] } unless length $self->[2][0];	531	shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0];
425	}	532	}
426	} while @{ $self->[2] };	533	} while @{ $self->[QUEUE] };
427		534
428	# everything written	535	# everything written
429	undef $self->[3];	536	undef $self->[WW];
430		537
431	# invoke run callback, if any	538	# invoke run callback, if any
432	$self->[4]->($self->[1]) if $self->[4];	539	if ($self->[CB]) {
		540	$self->[CB]->($self->[FH]);
		541	@$self = ();
		542	}
433	};	543	};
434		544
435	() # make sure we don't leak the watcher	545	() # make sure we don't leak the watcher
436	}
437
438	sub _new {
439	my ($self, $fh, $pid) = @_;
440
441	AnyEvent::Util::fh_nonblocking $fh, 1;
442
443	$self = bless [
444	$pid,
445	$fh,
446	[], # write queue - strings or fd's
447	undef, # AE watcher
448	], $self;
449
450	$self
451	}	546	}
452		547
453	# fork template from current process, used by AnyEvent::Fork::Early/Template	548	# fork template from current process, used by AnyEvent::Fork::Early/Template
454	sub _new_fork {	549	sub _new_fork {
455	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	550	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
…		…
460	if ($pid eq 0) {	555	if ($pid eq 0) {
461	require AnyEvent::Fork::Serve;	556	require AnyEvent::Fork::Serve;
462	$AnyEvent::Fork::Serve::OWNER = $parent;	557	$AnyEvent::Fork::Serve::OWNER = $parent;
463	close $fh;	558	close $fh;
464	$0 = "$_[1] of $parent";	559	$0 = "$_[1] of $parent";
465	$SIG{CHLD} = 'IGNORE';
466	AnyEvent::Fork::Serve::serve ($slave);	560	AnyEvent::Fork::Serve::serve ($slave);
467	exit 0;	561	exit 0;
468	} elsif (!$pid) {	562	} elsif (!$pid) {
469	die "AnyEvent::Fork::Early/Template: unable to fork template process: $!";	563	die "AnyEvent::Fork::Early/Template: unable to fork template process: $!";
470	}	564	}
…		…
524		618
525	You should use C<new> whenever possible, except when having a template	619	You should use C<new> whenever possible, except when having a template
526	process around is unacceptable.	620	process around is unacceptable.
527		621
528	The path to the perl interpreter is divined using various methods - first	622	The path to the perl interpreter is divined using various methods - first
529	C<$^X> is investigated to see if the path ends with something that sounds	623	C<$^X> is investigated to see if the path ends with something that looks
530	as if it were the perl interpreter. Failing this, the module falls back to	624	as if it were the perl interpreter. Failing this, the module falls back to
531	using C<$Config::Config{perlpath}>.	625	using C<$Config::Config{perlpath}>.
532		626
		627	The path to perl can also be overriden by setting the global variable
		628	C<$AnyEvent::Fork::PERL> - it's value will be used for all subsequent
		629	invocations.
		630
533	=cut	631	=cut
		632
		633	our $PERL;
534		634
535	sub new_exec {	635	sub new_exec {
536	my ($self) = @_;	636	my ($self) = @_;
537		637
538	return $EARLY->fork	638	return $EARLY->fork
539	if $EARLY;	639	if $EARLY;
540		640
		641	unless (defined $PERL) {
541	# first find path of perl	642	# first find path of perl
542	my $perl = $;	643	my $perl = $^X;
543		644
544	# first we try $^X, but the path must be absolute (always on win32), and end in sth.	645	# first we try $^X, but the path must be absolute (always on win32), and end in sth.
545	# that looks like perl. this obviously only works for posix and win32	646	# that looks like perl. this obviously only works for posix and win32
546	unless (	647	unless (
547	($^O eq "MSWin32" \|\| $perl =~ m%^/%)	648	($^O eq "MSWin32" \|\| $perl =~ m%^/%)
548	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i	649	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i
549	) {	650	) {
550	# if it doesn't look perlish enough, try Config	651	# if it doesn't look perlish enough, try Config
551	require Config;	652	require Config;
552	$perl = $Config::Config{perlpath};	653	$perl = $Config::Config{perlpath};
553	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;	654	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;
		655	}
		656
		657	$PERL = $perl;
554	}	658	}
555		659
556	require Proc::FastSpawn;	660	require Proc::FastSpawn;
557		661
558	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	662	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
…		…
566	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;	670	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;
567	my %env = %ENV;	671	my %env = %ENV;
568	$env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC;	672	$env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC;
569		673
570	my $pid = Proc::FastSpawn::spawn (	674	my $pid = Proc::FastSpawn::spawn (
571	$perl,	675	$PERL,
572	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],	676	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],
573	[map "$_=$env{$_}", keys %env],	677	[map "$_=$env{$_}", keys %env],
574	) or die "unable to spawn AnyEvent::Fork server: $!";	678	) or die "unable to spawn AnyEvent::Fork server: $!";
575		679
576	$self->_new ($fh, $pid)	680	$self->_new ($fh, $pid)
577	}	681	}
578		682
579	=item $pid = $proc->pid	683	=item $pid = $proc->pid
580		684
581	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
582	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.
583		690
584	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
585	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,
586	to clean up their zombies when they die.	693	you need to check whether a process is a diretc child by calling this
587		694	method, and possibly creating a child watcher or reap it manually.
588	All other processes are not direct children, and will be cleaned up by
589	AnyEvent::Fork itself.
590		695
591	=cut	696	=cut
592		697
593	sub pid {	698	sub pid {
594	$_[0][0]	699	$_[0][PID]
595	}	700	}
596		701
597	=item $proc = $proc->eval ($perlcode, @args)	702	=item $proc = $proc->eval ($perlcode, @args)
598		703
599	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
600	the strings specified by C<@args>, in the "main" package.	705	the strings specified by C<@args>, in the "main" package.
601		706
602	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
603	(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
604	to completely take over the process, use C<run> for that.	709	to completely take over the process, use C<run> for that.
…		…
666	sub send_fh {	771	sub send_fh {
667	my ($self, @fh) = @_;	772	my ($self, @fh) = @_;
668		773
669	for my $fh (@fh) {	774	for my $fh (@fh) {
670	$self->_cmd ("h");	775	$self->_cmd ("h");
671	push @{ $self->[2] }, \$fh;	776	push @{ $self->[QUEUE] }, \$fh;
672	}	777	}
673		778
674	$self	779	$self
675	}	780	}
676		781
…		…
725		830
726	Even if not used otherwise, the socket can be a good indicator for the	831	Even if not used otherwise, the socket can be a good indicator for the
727	existence of the process - if the other process exits, you get a readable	832	existence of the process - if the other process exits, you get a readable
728	event on it, because exiting the process closes the socket (if it didn't	833	event on it, because exiting the process closes the socket (if it didn't
729	create any children using fork).	834	create any children using fork).
		835
		836	=over 4
		837
		838	=item Compatibility to L<AnyEvent::Fork::Remote>
		839
		840	If you want to write code that works with both this module and
		841	L<AnyEvent::Fork::Remote>, you need to write your code so that it assumes
		842	there are two file handles for communications, which might not be unix
		843	domain sockets. The C<run> function should start like this:
		844
		845	sub run {
		846	my ($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
730		861
731	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
732	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.
733		864
734	my $pool = AnyEvent::Fork	865	my $pool = AnyEvent::Fork
…		…
762	=cut	893	=cut
763		894
764	sub run {	895	sub run {
765	my ($self, $func, $cb) = @_;	896	my ($self, $func, $cb) = @_;
766		897
767	$self->[4] = $cb;	898	$self->[CB] = $cb;
768	$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)
769	}	952	}
770		953
771	=back	954	=back
772		955
773	=head1 PERFORMANCE	956	=head1 PERFORMANCE
…		…
783		966
784	2079 new processes per second, using manual socketpair + fork	967	2079 new processes per second, using manual socketpair + fork
785		968
786	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
787	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
788	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
789	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
790	(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
791	of the socket first.	974	of the socket first.
792		975
793	2307 new processes per second, using AnyEvent::Fork->new	976	2307 new processes per second, using AnyEvent::Fork->new
…		…
800	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
801	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?
802		985
803	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
804	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
805	overhead introduced is canceled out.	988	overhead is canceled out.
806		989
807	If the benchmark process grows, the normal fork becomes even slower:	990	If the benchmark process grows, the normal fork becomes even slower:
808		991
809	1340 new processes, manual fork of a 20MB process	992	1340 new processes, manual fork of a 20MB process
810	731 new processes, manual fork of a 200MB process	993	731 new processes, manual fork of a 200MB process
…		…
870	initialising them, for example, by calling C<init Gtk2> manually.	1053	initialising them, for example, by calling C<init Gtk2> manually.
871		1054
872	=item exiting calls object destructors	1055	=item exiting calls object destructors
873		1056
874	This only applies to users of L<AnyEvent::Fork:Early> and	1057	This only applies to users of L<AnyEvent::Fork:Early> and
875	L<AnyEvent::Fork::Template>, or when initialiasing code creates objects	1058	L<AnyEvent::Fork::Template>, or when initialising code creates objects
876	that reference external resources.	1059	that reference external resources.
877		1060
878	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
879	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
880	Perl runs all destructors.	1063	Perl runs all destructors.
…		…
900	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
901	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
902	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
903	issues or other braindamage. Hrrrr.	1086	issues or other braindamage. Hrrrr.
904		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
905	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
906	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.
907		1114
908	=head1 SEE ALSO	1115	=head1 SEE ALSO
909		1116
910	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
911	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
912	program at a convenient time).	1121	program at a convenient time (part of this distribution).
913		1122
914	=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
915		1132
916	Marc Lehmann <schmorp@schmorp.de>	1133	Marc Lehmann <schmorp@schmorp.de>
917	http://home.schmorp.de/	1134	http://software.schmorp.de/pkg/AnyEvent-Fork
918		1135
919	=cut	1136	=cut
920		1137
921	1	1138	1
922		1139

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Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.39 by root, Sat Apr 6 22:39:37 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 1.39 by root, Sat Apr 6 22:39:37 2013 UTC vs.
Revision 1.63 by root, Wed Nov 26 13:36:18 2014 UTC