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

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.13 by root, Thu Apr 4 07:58:01 2013 UTC vs.
Revision 1.53 by root, Fri Apr 26 15:44:44 2013 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::Fork - everything you wanted to use fork() for, but couldn't	3	AnyEvent::Fork - everything you wanted to use fork() for, but couldn't
4		4
5	ATTENTION, this is a very early release, and very untested. Consider it a
6	technology preview.
7
8	=head1 SYNOPSIS	5	=head1 SYNOPSIS
9		6
10	use AnyEvent::Fork;	7	use AnyEvent::Fork;
11		8
12	##################################################################	9	AnyEvent::Fork
		10	->new
		11	->require ("MyModule")
		12	->run ("MyModule::server", my $cv = AE::cv);
		13
		14	my $fh = $cv->recv;
		15
		16	=head1 DESCRIPTION
		17
		18	This module allows you to create new processes, without actually forking
		19	them from your current process (avoiding the problems of forking), but
		20	preserving most of the advantages of fork.
		21
		22	It can be used to create new worker processes or new independent
		23	subprocesses for short- and long-running jobs, process pools (e.g. for use
		24	in pre-forked servers) but also to spawn new external processes (such as
		25	CGI scripts from a web server), which can be faster (and more well behaved)
		26	than using fork+exec in big processes.
		27
		28	Special care has been taken to make this module useful from other modules,
		29	while still supporting specialised environments such as L<App::Staticperl>
		30	or L<PAR::Packer>.
		31
		32	=head2 WHAT THIS MODULE IS NOT
		33
		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 -
		36	there is no back channel from the process back to you, and there is no RPC
		37	or message passing going on.
		38
		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
		41	by this module.
		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
		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.
		51
		52	=head2 COMPARISON TO OTHER MODULES
		53
		54	There is an abundance of modules on CPAN that do "something fork", such as
		55	L<Parallel::ForkManager>, L<AnyEvent::ForkManager>, L<AnyEvent::Worker>
		56	or L<AnyEvent::Subprocess>. There are modules that implement their own
		57	process management, such as L<AnyEvent::DBI>.
		58
		59	The problems that all these modules try to solve are real, however, none
		60	of them (from what I have seen) tackle the very real problems of unwanted
		61	memory sharing, efficiency, not being able to use event processing or
		62	similar modules in the processes they create.
		63
		64	This module doesn't try to replace any of them - instead it tries to solve
		65	the problem of creating processes with a minimum of fuss and overhead (and
		66	also luxury). Ideally, most of these would use AnyEvent::Fork internally,
		67	except they were written before AnyEvent:Fork was available, so obviously
		68	had to roll their own.
		69
		70	=head2 PROBLEM STATEMENT
		71
		72	There are two traditional ways to implement parallel processing on UNIX
		73	like operating systems - fork and process, and fork+exec and process. They
		74	have different advantages and disadvantages that I describe below,
		75	together with how this module tries to mitigate the disadvantages.
		76
		77	=over 4
		78
		79	=item Forking from a big process can be very slow.
		80
		81	A 5GB process needs 0.05s to fork on my 3.6GHz amd64 GNU/Linux box. This
		82	overhead is often shared with exec (because you have to fork first), but
		83	in some circumstances (e.g. when vfork is used), fork+exec can be much
		84	faster.
		85
		86	This module can help here by telling a small(er) helper process to fork,
		87	which is faster then forking the main process, and also uses vfork where
		88	possible. This gives the speed of vfork, with the flexibility of fork.
		89
		90	=item Forking usually creates a copy-on-write copy of the parent
		91	process.
		92
		93	For example, modules or data files that are loaded will not use additional
		94	memory after a fork. When exec'ing a new process, modules and data files
		95	might need to be loaded again, at extra CPU and memory cost. But when
		96	forking, literally all data structures are copied - if the program frees
		97	them and replaces them by new data, the child processes will retain the
		98	old version even if it isn't used, which can suddenly and unexpectedly
		99	increase memory usage when freeing memory.
		100
		101	The trade-off is between more sharing with fork (which can be good or
		102	bad), and no sharing with exec.
		103
		104	This module allows the main program to do a controlled fork, and allows
		105	modules to exec processes safely at any time. When creating a custom
		106	process pool you can take advantage of data sharing via fork without
		107	risking to share large dynamic data structures that will blow up child
		108	memory usage.
		109
		110	In other words, this module puts you into control over what is being
		111	shared and what isn't, at all times.
		112
		113	=item Exec'ing a new perl process might be difficult.
		114
		115	For example, it is not easy to find the correct path to the perl
		116	interpreter - C<$^X> might not be a perl interpreter at all.
		117
		118	This module tries hard to identify the correct path to the perl
		119	interpreter. With a cooperative main program, exec'ing the interpreter
		120	might not even be necessary, but even without help from the main program,
		121	it will still work when used from a module.
		122
		123	=item Exec'ing a new perl process might be slow, as all necessary modules
		124	have to be loaded from disk again, with no guarantees of success.
		125
		126	Long running processes might run into problems when perl is upgraded
		127	and modules are no longer loadable because they refer to a different
		128	perl version, or parts of a distribution are newer than the ones already
		129	loaded.
		130
		131	This module supports creating pre-initialised perl processes to be used as
		132	a template for new processes.
		133
		134	=item Forking might be impossible when a program is running.
		135
		136	For example, POSIX makes it almost impossible to fork from a
		137	multi-threaded program while doing anything useful in the child - in
		138	fact, if your perl program uses POSIX threads (even indirectly via
		139	e.g. L<IO::AIO> or L<threads>), you cannot call fork on the perl level
		140	anymore without risking corruption issues on a number of operating
		141	systems.
		142
		143	This module can safely fork helper processes at any time, by calling
		144	fork+exec in C, in a POSIX-compatible way (via L<Proc::FastSpawn>).
		145
		146	=item Parallel processing with fork might be inconvenient or difficult
		147	to implement. Modules might not work in both parent and child.
		148
		149	For example, when a program uses an event loop and creates watchers it
		150	becomes very hard to use the event loop from a child program, as the
		151	watchers already exist but are only meaningful in the parent. Worse, a
		152	module might want to use such a module, not knowing whether another module
		153	or the main program also does, leading to problems.
		154
		155	Apart from event loops, graphical toolkits also commonly fall into the
		156	"unsafe module" category, or just about anything that communicates with
		157	the external world, such as network libraries and file I/O modules, which
		158	usually don't like being copied and then allowed to continue in two
		159	processes.
		160
		161	With this module only the main program is allowed to create new processes
		162	by forking (because only the main program can know when it is still safe
		163	to do so) - all other processes are created via fork+exec, which makes it
		164	possible to use modules such as event loops or window interfaces safely.
		165
		166	=back
		167
		168	=head1 EXAMPLES
		169
13	# create a single new process, tell it to run your worker function	170	=head2 Create a single new process, tell it to run your worker function.
14		171
15	AnyEvent::Fork	172	AnyEvent::Fork
16	->new	173	->new
17	->require ("MyModule")	174	->require ("MyModule")
18	->run ("MyModule::worker, sub {	175	->run ("MyModule::worker, sub {
20		177
21	# now $master_filehandle is connected to the	178	# now $master_filehandle is connected to the
22	# $slave_filehandle in the new process.	179	# $slave_filehandle in the new process.
23	});	180	});
24		181
25	# MyModule::worker might look like this	182	C<MyModule> might look like this:
		183
		184	package MyModule;
		185
26	sub MyModule::worker {	186	sub worker {
27	my ($slave_filehandle) = @_;	187	my ($slave_filehandle) = @_;
28		188
29	# now $slave_filehandle is connected to the $master_filehandle	189	# now $slave_filehandle is connected to the $master_filehandle
30	# in the original prorcess. have fun!	190	# in the original prorcess. have fun!
31	}	191	}
32		192
33	##################################################################
34	# create a pool of server processes all accepting on the same socket	193	=head2 Create a pool of server processes all accepting on the same socket.
35		194
36	# create listener socket	195	# create listener socket
37	my $listener = ...;	196	my $listener = ...;
38		197
39	# create a pool template, initialise it and give it the socket	198	# create a pool template, initialise it and give it the socket
…		…
51	}	210	}
52		211
53	# now do other things - maybe use the filehandle provided by run	212	# now do other things - maybe use the filehandle provided by run
54	# to wait for the processes to die. or whatever.	213	# to wait for the processes to die. or whatever.
55		214
56	# My::Server::run might look like this	215	C<My::Server> might look like this:
57	sub My::Server::run {	216
		217	package My::Server;
		218
		219	sub run {
58	my ($slave, $listener, $id) = @_;	220	my ($slave, $listener, $id) = @_;
59		221
60	close $slave; # we do not use the socket, so close it to save resources	222	close $slave; # we do not use the socket, so close it to save resources
61		223
62	# we could go ballistic and use e.g. AnyEvent here, or IO::AIO,	224	# we could go ballistic and use e.g. AnyEvent here, or IO::AIO,
…		…
64	while (my $socket = $listener->accept) {	226	while (my $socket = $listener->accept) {
65	# do sth. with new socket	227	# do sth. with new socket
66	}	228	}
67	}	229	}
68		230
69	=head1 DESCRIPTION	231	=head2 use AnyEvent::Fork as a faster fork+exec
70		232
71	This module allows you to create new processes, without actually forking	233	This runs C</bin/echo hi>, with standard output redirected to F</tmp/log>
72	them from your current process (avoiding the problems of forking), but	234	and standard error redirected to the communications socket. It is usually
73	preserving most of the advantages of fork.	235	faster than fork+exec, but still lets you prepare the environment.
74		236
75	It can be used to create new worker processes or new independent	237	open my $output, ">/tmp/log" or die "$!";
76	subprocesses for short- and long-running jobs, process pools (e.g. for use
77	in pre-forked servers) but also to spawn new external processes (such as
78	CGI scripts from a webserver), which can be faster (and more well behaved)
79	than using fork+exec in big processes.
80		238
81	Special care has been taken to make this module useful from other modules,	239	AnyEvent::Fork
82	while still supporting specialised environments such as L<App::Staticperl>	240	->new
83	or L<PAR::Packer>.	241	->eval ('
		242	# compile a helper function for later use
		243	sub run {
		244	my ($fh, $output, @cmd) = @_;
84		245
85	=head1 PROBLEM STATEMENT	246	# perl will clear close-on-exec on STDOUT/STDERR
		247	open STDOUT, ">&", $output or die;
		248	open STDERR, ">&", $fh or die;
86		249
87	There are two ways to implement parallel processing on UNIX like operating	250	exec @cmd;
88	systems - fork and process, and fork+exec and process. They have different	251	}
89	advantages and disadvantages that I describe below, together with how this	252	')
90	module tries to mitigate the disadvantages.	253	->send_fh ($output)
		254	->send_arg ("/bin/echo", "hi")
		255	->run ("run", my $cv = AE::cv);
91		256
92	=over 4	257	my $stderr = $cv->recv;
93		258
94	=item Forking from a big process can be very slow (a 5GB process needs	259	=head2 For stingy users: put the worker code into a C<DATA> section.
95	0.05s to fork on my 3.6GHz amd64 GNU/Linux box for example). This overhead
96	is often shared with exec (because you have to fork first), but in some
97	circumstances (e.g. when vfork is used), fork+exec can be much faster.
98		260
99	This module can help here by telling a small(er) helper process to fork,	261	When you want to be stingy with files, you cna put your code into the
100	or fork+exec instead.	262	C<DATA> section of your module (or program):
101		263
102	=item Forking usually creates a copy-on-write copy of the parent	264	use AnyEvent::Fork;
103	process. Memory (for example, modules or data files that have been
104	will not take additional memory). When exec'ing a new process, modules
105	and data files might need to be loaded again, at extra cpu and memory
106	cost. Likewise when forking, all data structures are copied as well - if
107	the program frees them and replaces them by new data, the child processes
108	will retain the memory even if it isn't used.
109		265
110	This module allows the main program to do a controlled fork, and allows	266	AnyEvent::Fork
111	modules to exec processes safely at any time. When creating a custom	267	->new
112	process pool you can take advantage of data sharing via fork without	268	->eval (do { local $/; <DATA> })
113	risking to share large dynamic data structures that will blow up child	269	->run ("doit", sub { ... });
114	memory usage.
115		270
116	=item Exec'ing a new perl process might be difficult and slow. For	271	__DATA__
117	example, it is not easy to find the correct path to the perl interpreter,
118	and all modules have to be loaded from disk again. Long running processes
119	might run into problems when perl is upgraded for example.
120		272
121	This module supports creating pre-initialised perl processes to be used	273	sub doit {
122	as template, and also tries hard to identify the correct path to the perl	274	... do something!
123	interpreter. With a cooperative main program, exec'ing the interpreter	275	}
124	might not even be necessary.
125		276
126	=item Forking might be impossible when a program is running. For example,	277	=head2 For stingy standalone programs: do not rely on external files at
127	POSIX makes it almost impossible to fork from a multithreaded program and	278	all.
128	do anything useful in the child - strictly speaking, if your perl program
129	uses posix threads (even indirectly via e.g. L<IO::AIO> or L<threads>),
130	you cannot call fork on the perl level anymore, at all.
131		279
132	This module can safely fork helper processes at any time, by caling	280	For single-file scripts it can be inconvenient to rely on external
133	fork+exec in C, in a POSIX-compatible way.	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.
134		284
135	=item Parallel processing with fork might be inconvenient or difficult	285	Two modules help here - L<AnyEvent::Fork::Early> forks a template process
136	to implement. For example, when a program uses an event loop and creates	286	for all further calls to C<new_exec>, and L<AnyEvent::Fork::Template>
137	watchers it becomes very hard to use the event loop from a child	287	forks the main program as a template process.
138	program, as the watchers already exist but are only meaningful in the
139	parent. Worse, a module might want to use such a system, not knowing
140	whether another module or the main program also does, leading to problems.
141		288
142	This module only lets the main program create pools by forking (because	289	Here is how your main program should look like:
143	only the main program can know when it is still safe to do so) - all other
144	pools are created by fork+exec, after which such modules can again be
145	loaded.
146		290
147	=back	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;
148		327
149	=head1 CONCEPTS	328	=head1 CONCEPTS
150		329
151	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
152	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".
153		336
154	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
155	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,
156	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
157	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
…		…
169	needed the first time. Forking from this process shares the memory used	352	needed the first time. Forking from this process shares the memory used
170	for the perl interpreter with the new process, but loading modules takes	353	for the perl interpreter with the new process, but loading modules takes
171	time, and the memory is not shared with anything else.	354	time, and the memory is not shared with anything else.
172		355
173	This is ideal for when you only need one extra process of a kind, with the	356	This is ideal for when you only need one extra process of a kind, with the
174	option of starting and stipping it on demand.	357	option of starting and stopping it on demand.
175		358
176	Example:	359	Example:
177		360
178	AnyEvent::Fork	361	AnyEvent::Fork
179	->new	362	->new
…		…
194	modules you loaded) is shared between the processes, and each new process	377	modules you loaded) is shared between the processes, and each new process
195	consumes relatively little memory of its own.	378	consumes relatively little memory of its own.
196		379
197	The disadvantage of this approach is that you need to create a template	380	The disadvantage of this approach is that you need to create a template
198	process for the sole purpose of forking new processes from it, but if you	381	process for the sole purpose of forking new processes from it, but if you
199	only need a fixed number of proceses you can create them, and then destroy	382	only need a fixed number of processes you can create them, and then destroy
200	the template process.	383	the template process.
201		384
202	Example:	385	Example:
203		386
204	my $template = AnyEvent::Fork->new->require ("Some::Module");	387	my $template = AnyEvent::Fork->new->require ("Some::Module");
…		…
231	my ($fork_fh) = @_;	414	my ($fork_fh) = @_;
232	});	415	});
233		416
234	=back	417	=back
235		418
236	=head1 FUNCTIONS	419	=head1 THE C<AnyEvent::Fork> CLASS
		420
		421	This module exports nothing, and only implements a single class -
		422	C<AnyEvent::Fork>.
		423
		424	There are two class constructors that both create new processes - C<new>
		425	and C<new_exec>. The C<fork> method creates a new process by forking an
		426	existing one and could be considered a third constructor.
		427
		428	Most of the remaining methods deal with preparing the new process, by
		429	loading code, evaluating code and sending data to the new process. They
		430	usually return the process object, so you can chain method calls.
		431
		432	If a process object is destroyed before calling its C<run> method, then
		433	the process simply exits. After C<run> is called, all responsibility is
		434	passed to the specified function.
		435
		436	As long as there is any outstanding work to be done, process objects
		437	resist being destroyed, so there is no reason to store them unless you
		438	need them later - configure and forget works just fine.
237		439
238	=over 4	440	=over 4
239		441
240	=cut	442	=cut
241		443
242	package AnyEvent::Fork;	444	package AnyEvent::Fork;
243		445
244	use common::sense;	446	use common::sense;
245		447
246	use Socket ();	448	use Errno ();
247		449
248	use AnyEvent;	450	use AnyEvent;
249	use AnyEvent::Fork::Util;
250	use AnyEvent::Util ();	451	use AnyEvent::Util ();
251		452
252	our $VERSION = $AnyEvent::Fork::Util::VERSION;	453	use IO::FDPass;
253		454
254	our $PERL; # the path to the perl interpreter, deduces with various forms of magic	455	our $VERSION = '1.0';
255
256	=item my $pool = new AnyEvent::Fork key => value...
257
258	Create a new process pool. The following named parameters are supported:
259
260	=over 4
261
262	=back
263
264	=cut
265		456
266	# the early fork template process	457	# the early fork template process
267	our $EARLY;	458	our $EARLY;
268		459
269	# the empty template process	460	# the empty template process
270	our $TEMPLATE;	461	our $TEMPLATE;
271		462
		463	sub QUEUE() { 0 }
		464	sub FH() { 1 }
		465	sub WW() { 2 }
		466	sub PID() { 3 }
		467	sub CB() { 4 }
		468
		469	sub _new {
		470	my ($self, $fh, $pid) = @_;
		471
		472	AnyEvent::Util::fh_nonblocking $fh, 1;
		473
		474	$self = bless [
		475	[], # write queue - strings or fd's
		476	$fh,
		477	undef, # AE watcher
		478	$pid,
		479	], $self;
		480
		481	$self
		482	}
		483
272	sub _cmd {	484	sub _cmd {
273	my $self = shift;	485	my $self = shift;
274		486
275	#TODO: maybe append the packet to any existing string command already in the queue
276
277	# ideally, we would want to use "a (w/a)*" as format string, but perl versions	487	# ideally, we would want to use "a (w/a)*" as format string, but perl
278	# from at least 5.8.9 to 5.16.3 are all buggy and can't unpack it.	488	# versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack
279	push @{ $self->[2] }, pack "N/a", pack "(w/a)*", @_;	489	# it.
		490	push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1];
280		491
281	$self->[3] \|\|= AE::io $self->[1], 1, sub {	492	$self->[WW] \|\|= AE::io $self->[FH], 1, sub {
		493	do {
282	# send the next "thing" in the queue - either a reference to an fh,	494	# send the next "thing" in the queue - either a reference to an fh,
283	# or a plain string.	495	# or a plain string.
284		496
285	if (ref $self->[2][0]) {	497	if (ref $self->[QUEUE][0]) {
286	# send fh	498	# send fh
287	AnyEvent::Fork::Util::fd_send fileno $self->[1], fileno ${ $self->[2][0] }	499	unless (IO::FDPass::send fileno $self->[FH], fileno ${ $self->[QUEUE][0] }) {
		500	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;
		501	undef $self->[WW];
		502	die "AnyEvent::Fork: file descriptor send failure: $!";
		503	}
		504
288	and shift @{ $self->[2] };	505	shift @{ $self->[QUEUE] };
289		506
290	} else {	507	} else {
291	# send string	508	# send string
292	my $len = syswrite $self->[1], $self->[2][0]	509	my $len = syswrite $self->[FH], $self->[QUEUE][0];
		510
		511	unless ($len) {
		512	return if $! == Errno::EAGAIN \|\| $! == Errno::EWOULDBLOCK;
		513	undef $self->[WW];
293	or do { undef $self->[3]; die "AnyEvent::Fork: command write failure: $!" };	514	die "AnyEvent::Fork: command write failure: $!";
		515	}
294		516
295	substr $self->[2][0], 0, $len, "";	517	substr $self->[QUEUE][0], 0, $len, "";
296	shift @{ $self->[2] } unless length $self->[2][0];	518	shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0];
297	}	519	}
		520	} while @{ $self->[QUEUE] };
298		521
299	unless (@{ $self->[2] }) {	522	# everything written
300	undef $self->[3];	523	undef $self->[WW];
		524
301	# invoke run callback	525	# invoke run callback, if any
		526	if ($self->[CB]) {
302	$self->[0]->($self->[1]) if $self->[0];	527	$self->[CB]->($self->[FH]);
		528	@$self = ();
303	}	529	}
304	};	530	};
305	}
306		531
307	sub _new {	532	() # make sure we don't leak the watcher
308	my ($self, $fh) = @_;
309
310	AnyEvent::Util::fh_nonblocking $fh, 1;
311
312	$self = bless [
313	undef, # run callback
314	$fh,
315	[], # write queue - strings or fd's
316	undef, # AE watcher
317	], $self;
318
319	$self
320	}	533	}
321		534
322	# fork template from current process, used by AnyEvent::Fork::Early/Template	535	# fork template from current process, used by AnyEvent::Fork::Early/Template
323	sub _new_fork {	536	sub _new_fork {
324	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	537	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
…		…
330	require AnyEvent::Fork::Serve;	543	require AnyEvent::Fork::Serve;
331	$AnyEvent::Fork::Serve::OWNER = $parent;	544	$AnyEvent::Fork::Serve::OWNER = $parent;
332	close $fh;	545	close $fh;
333	$0 = "$_[1] of $parent";	546	$0 = "$_[1] of $parent";
334	AnyEvent::Fork::Serve::serve ($slave);	547	AnyEvent::Fork::Serve::serve ($slave);
335	AnyEvent::Fork::Util::_exit 0;	548	exit 0;
336	} elsif (!$pid) {	549	} elsif (!$pid) {
337	die "AnyEvent::Fork::Early/Template: unable to fork template process: $!";	550	die "AnyEvent::Fork::Early/Template: unable to fork template process: $!";
338	}	551	}
339		552
340	AnyEvent::Fork->_new ($fh)	553	AnyEvent::Fork->_new ($fh, $pid)
341	}	554	}
342		555
343	=item my $proc = new AnyEvent::Fork	556	=item my $proc = new AnyEvent::Fork
344		557
345	Create a new "empty" perl interpreter process and returns its process	558	Create a new "empty" perl interpreter process and returns its process
346	object for further manipulation.	559	object for further manipulation.
347		560
348	The new process is forked from a template process that is kept around	561	The new process is forked from a template process that is kept around
349	for this purpose. When it doesn't exist yet, it is created by a call to	562	for this purpose. When it doesn't exist yet, it is created by a call to
350	C<new_exec> and kept around for future calls.	563	C<new_exec> first and then stays around for future calls.
351
352	When the process object is destroyed, it will release the file handle
353	that connects it with the new process. When the new process has not yet
354	called C<run>, then the process will exit. Otherwise, what happens depends
355	entirely on the code that is executed.
356		564
357	=cut	565	=cut
358		566
359	sub new {	567	sub new {
360	my $class = shift;	568	my $class = shift;
…		…
396	reduces the amount of memory sharing that is possible, and is also slower.	604	reduces the amount of memory sharing that is possible, and is also slower.
397		605
398	You should use C<new> whenever possible, except when having a template	606	You should use C<new> whenever possible, except when having a template
399	process around is unacceptable.	607	process around is unacceptable.
400		608
401	The path to the perl interpreter is divined usign various methods - first	609	The path to the perl interpreter is divined using various methods - first
402	C<$^X> is investigated to see if the path ends with something that sounds	610	C<$^X> is investigated to see if the path ends with something that sounds
403	as if it were the perl interpreter. Failing this, the module falls back to	611	as if it were the perl interpreter. Failing this, the module falls back to
404	using C<$Config::Config{perlpath}>.	612	using C<$Config::Config{perlpath}>.
405		613
406	=cut	614	=cut
…		…
415	my $perl = $;	623	my $perl = $;
416		624
417	# first we try $^X, but the path must be absolute (always on win32), and end in sth.	625	# first we try $^X, but the path must be absolute (always on win32), and end in sth.
418	# that looks like perl. this obviously only works for posix and win32	626	# that looks like perl. this obviously only works for posix and win32
419	unless (	627	unless (
420	(AnyEvent::Fork::Util::WIN32 \|\| $perl =~ m%^/%)	628	($^O eq "MSWin32" \|\| $perl =~ m%^/%)
421	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i	629	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i
422	) {	630	) {
423	# if it doesn't look perlish enough, try Config	631	# if it doesn't look perlish enough, try Config
424	require Config;	632	require Config;
425	$perl = $Config::Config{perlpath};	633	$perl = $Config::Config{perlpath};
…		…
436	Proc::FastSpawn::fd_inherit (fileno $fh, 0);	644	Proc::FastSpawn::fd_inherit (fileno $fh, 0);
437		645
438	# quick. also doesn't work in win32. of course. what did you expect	646	# quick. also doesn't work in win32. of course. what did you expect
439	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;	647	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;
440	my %env = %ENV;	648	my %env = %ENV;
441	$env{PERL5LIB} = join +(AnyEvent::Fork::Util::WIN32 ? ";" : ":"), grep !ref, @INC;	649	$env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC;
442		650
443	Proc::FastSpawn::spawn (	651	my $pid = Proc::FastSpawn::spawn (
444	$perl,	652	$perl,
445	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],	653	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],
446	[map "$_=$env{$_}", keys %env],	654	[map "$_=$env{$_}", keys %env],
447	) or die "unable to spawn AnyEvent::Fork server: $!";	655	) or die "unable to spawn AnyEvent::Fork server: $!";
448		656
449	$self->_new ($fh)	657	$self->_new ($fh, $pid)
		658	}
		659
		660	=item $pid = $proc->pid
		661
		662	Returns the process id of the process I<iff it is a direct child of the
		663	process running AnyEvent::Fork>, and C<undef> otherwise.
		664
		665	Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and
		666	L<AnyEvent::Fork::Template> are direct children, and you are responsible
		667	to clean up their zombies when they die.
		668
		669	All other processes are not direct children, and will be cleaned up by
		670	AnyEvent::Fork itself.
		671
		672	=cut
		673
		674	sub pid {
		675	$_[0][PID]
450	}	676	}
451		677
452	=item $proc = $proc->eval ($perlcode, @args)	678	=item $proc = $proc->eval ($perlcode, @args)
453		679
454	Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to	680	Evaluates the given C<$perlcode> as ... Perl code, while setting C<@_> to
455	the strings specified by C<@args>.	681	the strings specified by C<@args>, in the "main" package.
456		682
457	This call is meant to do any custom initialisation that might be required	683	This call is meant to do any custom initialisation that might be required
458	(for example, the C<require> method uses it). It's not supposed to be used	684	(for example, the C<require> method uses it). It's not supposed to be used
459	to completely take over the process, use C<run> for that.	685	to completely take over the process, use C<run> for that.
460		686
461	The code will usually be executed after this call returns, and there is no	687	The code will usually be executed after this call returns, and there is no
462	way to pass anything back to the calling process. Any evaluation errors	688	way to pass anything back to the calling process. Any evaluation errors
463	will be reported to stderr and cause the process to exit.	689	will be reported to stderr and cause the process to exit.
464		690
		691	If you want to execute some code (that isn't in a module) to take over the
		692	process, you should compile a function via C<eval> first, and then call
		693	it via C<run>. This also gives you access to any arguments passed via the
		694	C<send_xxx> methods, such as file handles. See the L<use AnyEvent::Fork as
		695	a faster fork+exec> example to see it in action.
		696
465	Returns the process object for easy chaining of method calls.	697	Returns the process object for easy chaining of method calls.
466		698
467	=cut	699	=cut
468		700
469	sub eval {	701	sub eval {
470	my ($self, $code, @args) = @_;	702	my ($self, $code, @args) = @_;
471		703
472	$self->_cmd (e => $code, @args);	704	$self->_cmd (e => pack "(w/a)", $code, @args);
473		705
474	$self	706	$self
475	}	707	}
476		708
477	=item $proc = $proc->require ($module, ...)	709	=item $proc = $proc->require ($module, ...)
…		…
494	=item $proc = $proc->send_fh ($handle, ...)	726	=item $proc = $proc->send_fh ($handle, ...)
495		727
496	Send one or more file handles (I<not> file descriptors) to the process,	728	Send one or more file handles (I<not> file descriptors) to the process,
497	to prepare a call to C<run>.	729	to prepare a call to C<run>.
498		730
499	The process object keeps a reference to the handles until this is done,	731	The process object keeps a reference to the handles until they have
500	so you must not explicitly close the handles. This is most easily	732	been passed over to the process, so you must not explicitly close the
501	accomplished by simply not storing the file handles anywhere after passing	733	handles. This is most easily accomplished by simply not storing the file
502	them to this method.	734	handles anywhere after passing them to this method - when AnyEvent::Fork
		735	is finished using them, perl will automatically close them.
503		736
504	Returns the process object for easy chaining of method calls.	737	Returns the process object for easy chaining of method calls.
505		738
506	Example: pass an fh to a process, and release it without closing. it will	739	Example: pass a file handle to a process, and release it without
507	be closed automatically when it is no longer used.	740	closing. It will be closed automatically when it is no longer used.
508		741
509	$proc->send_fh ($my_fh);	742	$proc->send_fh ($my_fh);
510	undef $my_fh; # free the reference if you want, but DO NOT CLOSE IT	743	undef $my_fh; # free the reference if you want, but DO NOT CLOSE IT
511		744
512	=cut	745	=cut
…		…
514	sub send_fh {	747	sub send_fh {
515	my ($self, @fh) = @_;	748	my ($self, @fh) = @_;
516		749
517	for my $fh (@fh) {	750	for my $fh (@fh) {
518	$self->_cmd ("h");	751	$self->_cmd ("h");
519	push @{ $self->[2] }, \$fh;	752	push @{ $self->[QUEUE] }, \$fh;
520	}	753	}
521		754
522	$self	755	$self
523	}	756	}
524		757
525	=item $proc = $proc->send_arg ($string, ...)	758	=item $proc = $proc->send_arg ($string, ...)
526		759
527	Send one or more argument strings to the process, to prepare a call to	760	Send one or more argument strings to the process, to prepare a call to
528	C<run>. The strings can be any octet string.	761	C<run>. The strings can be any octet strings.
529		762
		763	The protocol is optimised to pass a moderate number of relatively short
		764	strings - while you can pass up to 4GB of data in one go, this is more
		765	meant to pass some ID information or other startup info, not big chunks of
		766	data.
		767
530	Returns the process object for easy chaining of emthod calls.	768	Returns the process object for easy chaining of method calls.
531		769
532	=cut	770	=cut
533		771
534	sub send_arg {	772	sub send_arg {
535	my ($self, @arg) = @_;	773	my ($self, @arg) = @_;
536		774
537	$self->_cmd (a => @arg);	775	$self->_cmd (a => pack "(w/a)", @arg);
538		776
539	$self	777	$self
540	}	778	}
541		779
542	=item $proc->run ($func, $cb->($fh))	780	=item $proc->run ($func, $cb->($fh))
543		781
544	Enter the function specified by the fully qualified name in C<$func> in	782	Enter the function specified by the function name in C<$func> in the
545	the process. The function is called with the communication socket as first	783	process. The function is called with the communication socket as first
546	argument, followed by all file handles and string arguments sent earlier	784	argument, followed by all file handles and string arguments sent earlier
547	via C<send_fh> and C<send_arg> methods, in the order they were called.	785	via C<send_fh> and C<send_arg> methods, in the order they were called.
548		786
549	If the called function returns, the process exits.
550
551	Preparing the process can take time - when the process is ready, the
552	callback is invoked with the local communications socket as argument.
553
554	The process object becomes unusable on return from this function.	787	The process object becomes unusable on return from this function - any
		788	further method calls result in undefined behaviour.
		789
		790	The function name should be fully qualified, but if it isn't, it will be
		791	looked up in the C<main> package.
		792
		793	If the called function returns, doesn't exist, or any error occurs, the
		794	process exits.
		795
		796	Preparing the process is done in the background - when all commands have
		797	been sent, the callback is invoked with the local communications socket
		798	as argument. At this point you can start using the socket in any way you
		799	like.
555		800
556	If the communication socket isn't used, it should be closed on both sides,	801	If the communication socket isn't used, it should be closed on both sides,
557	to save on kernel memory.	802	to save on kernel memory.
558		803
559	The socket is non-blocking in the parent, and blocking in the newly	804	The socket is non-blocking in the parent, and blocking in the newly
560	created process. The close-on-exec flag is set on both. Even if not used	805	created process. The close-on-exec flag is set in both.
		806
561	otherwise, the socket can be a good indicator for the existance of the	807	Even if not used otherwise, the socket can be a good indicator for the
562	process - if the other process exits, you get a readable event on it,	808	existence of the process - if the other process exits, you get a readable
563	because exiting the process closes the socket (if it didn't create any	809	event on it, because exiting the process closes the socket (if it didn't
564	children using fork).	810	create any children using fork).
565		811
566	Example: create a template for a process pool, pass a few strings, some	812	Example: create a template for a process pool, pass a few strings, some
567	file handles, then fork, pass one more string, and run some code.	813	file handles, then fork, pass one more string, and run some code.
568		814
569	my $pool = AnyEvent::Fork	815	my $pool = AnyEvent::Fork
…		…
577	->send_arg ("str3")	823	->send_arg ("str3")
578	->run ("Some::function", sub {	824	->run ("Some::function", sub {
579	my ($fh) = @_;	825	my ($fh) = @_;
580		826
581	# fh is nonblocking, but we trust that the OS can accept these	827	# fh is nonblocking, but we trust that the OS can accept these
582	# extra 3 octets anyway.	828	# few octets anyway.
583	syswrite $fh, "hi #$_\n";	829	syswrite $fh, "hi #$_\n";
584		830
585	# $fh is being closed here, as we don't store it anywhere	831	# $fh is being closed here, as we don't store it anywhere
586	});	832	});
587	}	833	}
…		…
589	# Some::function might look like this - all parameters passed before fork	835	# Some::function might look like this - all parameters passed before fork
590	# and after will be passed, in order, after the communications socket.	836	# and after will be passed, in order, after the communications socket.
591	sub Some::function {	837	sub Some::function {
592	my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_;	838	my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_;
593		839
594	print scalar <$fh>; # prints "hi 1\n" and "hi 2\n"	840	print scalar <$fh>; # prints "hi #1\n" and "hi #2\n" in any order
595	}	841	}
596		842
597	=cut	843	=cut
598		844
599	sub run {	845	sub run {
600	my ($self, $func, $cb) = @_;	846	my ($self, $func, $cb) = @_;
601		847
602	$self->[0] = $cb;	848	$self->[CB] = $cb;
603	$self->_cmd (r => $func);	849	$self->_cmd (r => $func);
604	}	850	}
		851
		852	=back
		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
		972	=head1 PERFORMANCE
		973
		974	Now for some unscientific benchmark numbers (all done on an amd64
		975	GNU/Linux box). These are intended to give you an idea of the relative
		976	performance you can expect, they are not meant to be absolute performance
		977	numbers.
		978
		979	OK, so, I ran a simple benchmark that creates a socket pair, forks, calls
		980	exit in the child and waits for the socket to close in the parent. I did
		981	load AnyEvent, EV and AnyEvent::Fork, for a total process size of 5100kB.
		982
		983	2079 new processes per second, using manual socketpair + fork
		984
		985	Then I did the same thing, but instead of calling fork, I called
		986	AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the
		987	socket from the child to close on exit. This does the same thing as manual
		988	socket pair + fork, except that what is forked is the template process
		989	(2440kB), and the socket needs to be passed to the server at the other end
		990	of the socket first.
		991
		992	2307 new processes per second, using AnyEvent::Fork->new
		993
		994	And finally, using C<new_exec> instead C<new>, using vforks+execs to exec
		995	a new perl interpreter and compile the small server each time, I get:
		996
		997	479 vfork+execs per second, using AnyEvent::Fork->new_exec
		998
		999	So how can C<< AnyEvent->new >> be faster than a standard fork, even
		1000	though it uses the same operations, but adds a lot of overhead?
		1001
		1002	The difference is simply the process size: forking the 5MB process takes
		1003	so much longer than forking the 2.5MB template process that the extra
		1004	overhead is canceled out.
		1005
		1006	If the benchmark process grows, the normal fork becomes even slower:
		1007
		1008	1340 new processes, manual fork of a 20MB process
		1009	731 new processes, manual fork of a 200MB process
		1010	235 new processes, manual fork of a 2000MB process
		1011
		1012	What that means (to me) is that I can use this module without having a bad
		1013	conscience because of the extra overhead required to start new processes.
		1014
		1015	=head1 TYPICAL PROBLEMS
		1016
		1017	This section lists typical problems that remain. I hope by recognising
		1018	them, most can be avoided.
		1019
		1020	=over 4
		1021
		1022	=item leaked file descriptors for exec'ed processes
		1023
		1024	POSIX systems inherit file descriptors by default when exec'ing a new
		1025	process. While perl itself laudably sets the close-on-exec flags on new
		1026	file handles, most C libraries don't care, and even if all cared, it's
		1027	often not possible to set the flag in a race-free manner.
		1028
		1029	That means some file descriptors can leak through. And since it isn't
		1030	possible to know which file descriptors are "good" and "necessary" (or
		1031	even to know which file descriptors are open), there is no good way to
		1032	close the ones that might harm.
		1033
		1034	As an example of what "harm" can be done consider a web server that
		1035	accepts connections and afterwards some module uses AnyEvent::Fork for the
		1036	first time, causing it to fork and exec a new process, which might inherit
		1037	the network socket. When the server closes the socket, it is still open
		1038	in the child (which doesn't even know that) and the client might conclude
		1039	that the connection is still fine.
		1040
		1041	For the main program, there are multiple remedies available -
		1042	L<AnyEvent::Fork::Early> is one, creating a process early and not using
		1043	C<new_exec> is another, as in both cases, the first process can be exec'ed
		1044	well before many random file descriptors are open.
		1045
		1046	In general, the solution for these kind of problems is to fix the
		1047	libraries or the code that leaks those file descriptors.
		1048
		1049	Fortunately, most of these leaked descriptors do no harm, other than
		1050	sitting on some resources.
		1051
		1052	=item leaked file descriptors for fork'ed processes
		1053
		1054	Normally, L<AnyEvent::Fork> does start new processes by exec'ing them,
		1055	which closes file descriptors not marked for being inherited.
		1056
		1057	However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer
		1058	a way to create these processes by forking, and this leaks more file
		1059	descriptors than exec'ing them, as there is no way to mark descriptors as
		1060	"close on fork".
		1061
		1062	An example would be modules like L<EV>, L<IO::AIO> or L<Gtk2>. Both create
		1063	pipes for internal uses, and L<Gtk2> might open a connection to the X
		1064	server. L<EV> and L<IO::AIO> can deal with fork, but Gtk2 might have
		1065	trouble with a fork.
		1066
		1067	The solution is to either not load these modules before use'ing
		1068	L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay
		1069	initialising them, for example, by calling C<init Gtk2> manually.
		1070
		1071	=item exiting calls object destructors
		1072
		1073	This only applies to users of L<AnyEvent::Fork:Early> and
		1074	L<AnyEvent::Fork::Template>, or when initialising code creates objects
		1075	that reference external resources.
		1076
		1077	When a process created by AnyEvent::Fork exits, it might do so by calling
		1078	exit, or simply letting perl reach the end of the program. At which point
		1079	Perl runs all destructors.
		1080
		1081	Not all destructors are fork-safe - for example, an object that represents
		1082	the connection to an X display might tell the X server to free resources,
		1083	which is inconvenient when the "real" object in the parent still needs to
		1084	use them.
		1085
		1086	This is obviously not a problem for L<AnyEvent::Fork::Early>, as you used
		1087	it as the very first thing, right?
		1088
		1089	It is a problem for L<AnyEvent::Fork::Template> though - and the solution
		1090	is to not create objects with nontrivial destructors that might have an
		1091	effect outside of Perl.
605		1092
606	=back	1093	=back
607		1094
608	=head1 PORTABILITY NOTES	1095	=head1 PORTABILITY NOTES
609		1096
610	Native win32 perls are somewhat supported (AnyEvent::Fork::Early is a nop,	1097	Native win32 perls are somewhat supported (AnyEvent::Fork::Early is a nop,
611	and ::Template is not going to work), and it cost a lot of blood and sweat	1098	and ::Template is not going to work), and it cost a lot of blood and sweat
612	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
613	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
614	useful that you cna do with it without running into memory corruption	1101	useful that you can do with it without running into memory corruption
615	issues or other braindamage. Hrrrr.	1102	issues or other braindamage. Hrrrr.
616		1103
617	Cygwin perl is not supported at the moment, as it should implement fd	1104	Since fork is endlessly broken on win32 perls (it doesn't even remotely
618	passing, but doesn't, and rolling my own is hard, as cygwin doesn't	1105	work within it's documented limits) and quite obviously it's not getting
619	support enough functionality to do it.	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
		1109	Cygwin perl is not supported at the moment due to some hilarious
		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.
620		1113
621	=head1 SEE ALSO	1114	=head1 SEE ALSO
622		1115
623	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
624	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
625	program at a convenient time).	1120	program at a convenient time (part of this distribution).
626		1121
627	=head1 AUTHOR	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).
		1125
		1126	=head1 AUTHOR AND CONTACT INFORMATION
628		1127
629	Marc Lehmann <schmorp@schmorp.de>	1128	Marc Lehmann <schmorp@schmorp.de>
630	http://home.schmorp.de/	1129	http://software.schmorp.de/pkg/AnyEvent-Fork
631		1130
632	=cut	1131	=cut
633		1132
634	1	1133	1
635		1134

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Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.13 by root, Thu Apr 4 07:58:01 2013 UTC vs. Revision 1.53 by root, Fri Apr 26 15:44:44 2013 UTC

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Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.13 by root, Thu Apr 4 07:58:01 2013 UTC vs.
Revision 1.53 by root, Fri Apr 26 15:44:44 2013 UTC