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

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.10 by root, Thu Apr 4 06:09:15 2013 UTC vs.
Revision 1.59 by root, Fri Aug 30 12:06:48 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 $PERL; # the path to the perl interpreter, deduces with various forms of magic	453	use IO::FDPass;
253		454
254	=item my $pool = new AnyEvent::Fork key => value...	455	our $VERSION = 1.1;
255
256	Create a new process pool. The following named parameters are supported:
257
258	=over 4
259
260	=back
261
262	=cut
263		456
264	# the early fork template process	457	# the early fork template process
265	our $EARLY;	458	our $EARLY;
266		459
267	# the empty template process	460	# the empty template process
268	our $TEMPLATE;	461	our $TEMPLATE;
269		462
		463	sub QUEUE() { 0 }
		464	sub FH() { 1 }
		465	sub WW() { 2 }
		466	sub PID() { 3 }
		467	sub CB() { 4 }
		468
		469	sub _new {
		470	my ($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
270	sub _cmd {	484	sub _cmd {
271	my $self = shift;	485	my $self = shift;
272		486
273	#TODO: maybe append the packet to any existing string command already in the queue
274
275	# 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
276	# 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
277	push @{ $self->[2] }, pack "N/a", pack "(w/a)*", @_;	489	# it.
		490	push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1];
278		491
279	$self->[3] \|\|= AE::io $self->[1], 1, sub {	492	$self->[WW] \|\|= AE::io $self->[FH], 1, sub {
		493	do {
280	# 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,
281	# or a plain string.	495	# or a plain string.
282		496
283	if (ref $self->[2][0]) {	497	if (ref $self->[QUEUE][0]) {
284	# send fh	498	# send fh
285	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
286	and shift @{ $self->[2] };	505	shift @{ $self->[QUEUE] };
287		506
288	} else {	507	} else {
289	# send string	508	# send string
290	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];
291	or do { undef $self->[3]; die "AnyEvent::Fork: command write failure: $!" };	514	die "AnyEvent::Fork: command write failure: $!";
		515	}
292		516
293	substr $self->[2][0], 0, $len, "";	517	substr $self->[QUEUE][0], 0, $len, "";
294	shift @{ $self->[2] } unless length $self->[2][0];	518	shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0];
295	}	519	}
		520	} while @{ $self->[QUEUE] };
296		521
297	unless (@{ $self->[2] }) {	522	# everything written
298	undef $self->[3];	523	undef $self->[WW];
		524
299	# invoke run callback	525	# invoke run callback, if any
		526	if ($self->[CB]) {
300	$self->[0]->($self->[1]) if $self->[0];	527	$self->[CB]->($self->[FH]);
		528	@$self = ();
301	}	529	}
302	};	530	};
303	}
304		531
305	sub _new {	532	() # make sure we don't leak the watcher
306	my ($self, $fh) = @_;
307
308	AnyEvent::Util::fh_nonblocking $fh, 1;
309
310	$self = bless [
311	undef, # run callback
312	$fh,
313	[], # write queue - strings or fd's
314	undef, # AE watcher
315	], $self;
316
317	$self
318	}	533	}
319		534
320	# fork template from current process, used by AnyEvent::Fork::Early/Template	535	# fork template from current process, used by AnyEvent::Fork::Early/Template
321	sub _new_fork {	536	sub _new_fork {
322	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	537	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
…		…
328	require AnyEvent::Fork::Serve;	543	require AnyEvent::Fork::Serve;
329	$AnyEvent::Fork::Serve::OWNER = $parent;	544	$AnyEvent::Fork::Serve::OWNER = $parent;
330	close $fh;	545	close $fh;
331	$0 = "$_[1] of $parent";	546	$0 = "$_[1] of $parent";
332	AnyEvent::Fork::Serve::serve ($slave);	547	AnyEvent::Fork::Serve::serve ($slave);
333	AnyEvent::Fork::Util::_exit 0;	548	exit 0;
334	} elsif (!$pid) {	549	} elsif (!$pid) {
335	die "AnyEvent::Fork::Early/Template: unable to fork template process: $!";	550	die "AnyEvent::Fork::Early/Template: unable to fork template process: $!";
336	}	551	}
337		552
338	AnyEvent::Fork->_new ($fh)	553	AnyEvent::Fork->_new ($fh, $pid)
339	}	554	}
340		555
341	=item my $proc = new AnyEvent::Fork	556	=item my $proc = new AnyEvent::Fork
342		557
343	Create a new "empty" perl interpreter process and returns its process	558	Create a new "empty" perl interpreter process and returns its process
344	object for further manipulation.	559	object for further manipulation.
345		560
346	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
347	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
348	C<new_exec> and kept around for future calls.	563	C<new_exec> first and then stays around for future calls.
349
350	When the process object is destroyed, it will release the file handle
351	that connects it with the new process. When the new process has not yet
352	called C<run>, then the process will exit. Otherwise, what happens depends
353	entirely on the code that is executed.
354		564
355	=cut	565	=cut
356		566
357	sub new {	567	sub new {
358	my $class = shift;	568	my $class = shift;
…		…
394	reduces the amount of memory sharing that is possible, and is also slower.	604	reduces the amount of memory sharing that is possible, and is also slower.
395		605
396	You should use C<new> whenever possible, except when having a template	606	You should use C<new> whenever possible, except when having a template
397	process around is unacceptable.	607	process around is unacceptable.
398		608
399	The path to the perl interpreter is divined usign various methods - first	609	The path to the perl interpreter is divined using various methods - first
400	C<$^X> is investigated to see if the path ends with something that sounds	610	C<$^X> is investigated to see if the path ends with something that looks
401	as if it were the perl interpreter. Failing this, the module falls back to	611	as if it were the perl interpreter. Failing this, the module falls back to
402	using C<$Config::Config{perlpath}>.	612	using C<$Config::Config{perlpath}>.
403		613
		614	The path to perl can also be overriden by setting the global variable
		615	C<$AnyEvent::Fork::PERL> - it's value will be used for all subsequent
		616	invocations.
		617
404	=cut	618	=cut
		619
		620	our $PERL;
405		621
406	sub new_exec {	622	sub new_exec {
407	my ($self) = @_;	623	my ($self) = @_;
408		624
409	return $EARLY->fork	625	return $EARLY->fork
410	if $EARLY;	626	if $EARLY;
411		627
		628	unless (defined $PERL) {
412	# first find path of perl	629	# first find path of perl
413	my $perl = $;	630	my $perl = $;
414		631
415	# first we try $^X, but the path must be absolute (always on win32), and end in sth.	632	# first we try $^X, but the path must be absolute (always on win32), and end in sth.
416	# that looks like perl. this obviously only works for posix and win32	633	# that looks like perl. this obviously only works for posix and win32
417	unless (	634	unless (
418	(AnyEvent::Fork::Util::WIN32 \|\| $perl =~ m%^/%)	635	($^O eq "MSWin32" \|\| $perl =~ m%^/%)
419	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i	636	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i
420	) {	637	) {
421	# if it doesn't look perlish enough, try Config	638	# if it doesn't look perlish enough, try Config
422	require Config;	639	require Config;
423	$perl = $Config::Config{perlpath};	640	$perl = $Config::Config{perlpath};
424	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;	641	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;
		642	}
		643
		644	$PERL = $perl;
425	}	645	}
426		646
427	require Proc::FastSpawn;	647	require Proc::FastSpawn;
428		648
429	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	649	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
…		…
434	Proc::FastSpawn::fd_inherit (fileno $fh, 0);	654	Proc::FastSpawn::fd_inherit (fileno $fh, 0);
435		655
436	# quick. also doesn't work in win32. of course. what did you expect	656	# quick. also doesn't work in win32. of course. what did you expect
437	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;	657	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;
438	my %env = %ENV;	658	my %env = %ENV;
439	$env{PERL5LIB} = join +(AnyEvent::Fork::Util::WIN32 ? ";" : ":"), grep !ref, @INC;	659	$env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC;
440		660
441	Proc::FastSpawn::spawn (	661	my $pid = Proc::FastSpawn::spawn (
442	$perl,	662	$PERL,
443	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],	663	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],
444	[map "$_=$env{$_}", keys %env],	664	[map "$_=$env{$_}", keys %env],
445	) or die "unable to spawn AnyEvent::Fork server: $!";	665	) or die "unable to spawn AnyEvent::Fork server: $!";
446		666
447	$self->_new ($fh)	667	$self->_new ($fh, $pid)
		668	}
		669
		670	=item $pid = $proc->pid
		671
		672	Returns the process id of the process I<iff it is a direct child of the
		673	process running AnyEvent::Fork>, and C<undef> otherwise. As a general
		674	rule (that you cannot rely upon), processes created via C<new_exec>,
		675	L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template> are direct
		676	children, while all other processes are not.
		677
		678	Or in other words, you do not normally have to take care of zombies for
		679	processes created via C<new>, but when in doubt, or zombies are a problem,
		680	you need to check whether a process is a diretc child by calling this
		681	method, and possibly creating a child watcher or reap it manually.
		682
		683	=cut
		684
		685	sub pid {
		686	$_[0][PID]
448	}	687	}
449		688
450	=item $proc = $proc->eval ($perlcode, @args)	689	=item $proc = $proc->eval ($perlcode, @args)
451		690
452	Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to	691	Evaluates the given C<$perlcode> as ... Perl code, while setting C<@_> to
453	the strings specified by C<@args>.	692	the strings specified by C<@args>, in the "main" package.
454		693
455	This call is meant to do any custom initialisation that might be required	694	This call is meant to do any custom initialisation that might be required
456	(for example, the C<require> method uses it). It's not supposed to be used	695	(for example, the C<require> method uses it). It's not supposed to be used
457	to completely take over the process, use C<run> for that.	696	to completely take over the process, use C<run> for that.
458		697
459	The code will usually be executed after this call returns, and there is no	698	The code will usually be executed after this call returns, and there is no
460	way to pass anything back to the calling process. Any evaluation errors	699	way to pass anything back to the calling process. Any evaluation errors
461	will be reported to stderr and cause the process to exit.	700	will be reported to stderr and cause the process to exit.
462		701
		702	If you want to execute some code (that isn't in a module) to take over the
		703	process, you should compile a function via C<eval> first, and then call
		704	it via C<run>. This also gives you access to any arguments passed via the
		705	C<send_xxx> methods, such as file handles. See the L<use AnyEvent::Fork as
		706	a faster fork+exec> example to see it in action.
		707
463	Returns the process object for easy chaining of method calls.	708	Returns the process object for easy chaining of method calls.
464		709
465	=cut	710	=cut
466		711
467	sub eval {	712	sub eval {
468	my ($self, $code, @args) = @_;	713	my ($self, $code, @args) = @_;
469		714
470	$self->_cmd (e => $code, @args);	715	$self->_cmd (e => pack "(w/a)", $code, @args);
471		716
472	$self	717	$self
473	}	718	}
474		719
475	=item $proc = $proc->require ($module, ...)	720	=item $proc = $proc->require ($module, ...)
…		…
492	=item $proc = $proc->send_fh ($handle, ...)	737	=item $proc = $proc->send_fh ($handle, ...)
493		738
494	Send one or more file handles (I<not> file descriptors) to the process,	739	Send one or more file handles (I<not> file descriptors) to the process,
495	to prepare a call to C<run>.	740	to prepare a call to C<run>.
496		741
497	The process object keeps a reference to the handles until this is done,	742	The process object keeps a reference to the handles until they have
498	so you must not explicitly close the handles. This is most easily	743	been passed over to the process, so you must not explicitly close the
499	accomplished by simply not storing the file handles anywhere after passing	744	handles. This is most easily accomplished by simply not storing the file
500	them to this method.	745	handles anywhere after passing them to this method - when AnyEvent::Fork
		746	is finished using them, perl will automatically close them.
501		747
502	Returns the process object for easy chaining of method calls.	748	Returns the process object for easy chaining of method calls.
503		749
504	Example: pass an fh to a process, and release it without closing. it will	750	Example: pass a file handle to a process, and release it without
505	be closed automatically when it is no longer used.	751	closing. It will be closed automatically when it is no longer used.
506		752
507	$proc->send_fh ($my_fh);	753	$proc->send_fh ($my_fh);
508	undef $my_fh; # free the reference if you want, but DO NOT CLOSE IT	754	undef $my_fh; # free the reference if you want, but DO NOT CLOSE IT
509		755
510	=cut	756	=cut
…		…
512	sub send_fh {	758	sub send_fh {
513	my ($self, @fh) = @_;	759	my ($self, @fh) = @_;
514		760
515	for my $fh (@fh) {	761	for my $fh (@fh) {
516	$self->_cmd ("h");	762	$self->_cmd ("h");
517	push @{ $self->[2] }, \$fh;	763	push @{ $self->[QUEUE] }, \$fh;
518	}	764	}
519		765
520	$self	766	$self
521	}	767	}
522		768
523	=item $proc = $proc->send_arg ($string, ...)	769	=item $proc = $proc->send_arg ($string, ...)
524		770
525	Send one or more argument strings to the process, to prepare a call to	771	Send one or more argument strings to the process, to prepare a call to
526	C<run>. The strings can be any octet string.	772	C<run>. The strings can be any octet strings.
527		773
		774	The protocol is optimised to pass a moderate number of relatively short
		775	strings - while you can pass up to 4GB of data in one go, this is more
		776	meant to pass some ID information or other startup info, not big chunks of
		777	data.
		778
528	Returns the process object for easy chaining of emthod calls.	779	Returns the process object for easy chaining of method calls.
529		780
530	=cut	781	=cut
531		782
532	sub send_arg {	783	sub send_arg {
533	my ($self, @arg) = @_;	784	my ($self, @arg) = @_;
534		785
535	$self->_cmd (a => @arg);	786	$self->_cmd (a => pack "(w/a)", @arg);
536		787
537	$self	788	$self
538	}	789	}
539		790
540	=item $proc->run ($func, $cb->($fh))	791	=item $proc->run ($func, $cb->($fh))
541		792
542	Enter the function specified by the fully qualified name in C<$func> in	793	Enter the function specified by the function name in C<$func> in the
543	the process. The function is called with the communication socket as first	794	process. The function is called with the communication socket as first
544	argument, followed by all file handles and string arguments sent earlier	795	argument, followed by all file handles and string arguments sent earlier
545	via C<send_fh> and C<send_arg> methods, in the order they were called.	796	via C<send_fh> and C<send_arg> methods, in the order they were called.
546		797
547	If the called function returns, the process exits.
548
549	Preparing the process can take time - when the process is ready, the
550	callback is invoked with the local communications socket as argument.
551
552	The process object becomes unusable on return from this function.	798	The process object becomes unusable on return from this function - any
		799	further method calls result in undefined behaviour.
		800
		801	The function name should be fully qualified, but if it isn't, it will be
		802	looked up in the C<main> package.
		803
		804	If the called function returns, doesn't exist, or any error occurs, the
		805	process exits.
		806
		807	Preparing the process is done in the background - when all commands have
		808	been sent, the callback is invoked with the local communications socket
		809	as argument. At this point you can start using the socket in any way you
		810	like.
553		811
554	If the communication socket isn't used, it should be closed on both sides,	812	If the communication socket isn't used, it should be closed on both sides,
555	to save on kernel memory.	813	to save on kernel memory.
556		814
557	The socket is non-blocking in the parent, and blocking in the newly	815	The socket is non-blocking in the parent, and blocking in the newly
558	created process. The close-on-exec flag is set on both. Even if not used	816	created process. The close-on-exec flag is set in both.
		817
559	otherwise, the socket can be a good indicator for the existance of the	818	Even if not used otherwise, the socket can be a good indicator for the
560	process - if the other process exits, you get a readable event on it,	819	existence of the process - if the other process exits, you get a readable
561	because exiting the process closes the socket (if it didn't create any	820	event on it, because exiting the process closes the socket (if it didn't
562	children using fork).	821	create any children using fork).
		822
		823	=over 4
		824
		825	=item Compatibility to L<AnyEvent::Fork::Remote>
		826
		827	If you want to write code that works with both this module and
		828	L<AnyEvent::Fork::Remote>, you need to write your code so that it assumes
		829	there are two file handles for communications, which might not be unix
		830	domain sockets. The C<run> function should start like this:
		831
		832	sub run {
		833	my ($rfh, @args) = @_; # @args is your normal arguments
		834	my $wfh = fileno $rfh ? $rfh : *STDOUT;
		835
		836	# now use $rfh for reading and $wfh for writing
		837	}
		838
		839	This checks whether the passed file handle is, in fact, the process
		840	C<STDIN> handle. If it is, then the function was invoked visa
		841	L<AnyEvent::Fork::Remote>, so STDIN should be used for reading and
		842	C<STDOUT> should be used for writing.
		843
		844	In all other cases, the function was called via this module, and there is
		845	only one file handle that should be sued for reading and writing.
		846
		847	=back
563		848
564	Example: create a template for a process pool, pass a few strings, some	849	Example: create a template for a process pool, pass a few strings, some
565	file handles, then fork, pass one more string, and run some code.	850	file handles, then fork, pass one more string, and run some code.
566		851
567	my $pool = AnyEvent::Fork	852	my $pool = AnyEvent::Fork
…		…
575	->send_arg ("str3")	860	->send_arg ("str3")
576	->run ("Some::function", sub {	861	->run ("Some::function", sub {
577	my ($fh) = @_;	862	my ($fh) = @_;
578		863
579	# fh is nonblocking, but we trust that the OS can accept these	864	# fh is nonblocking, but we trust that the OS can accept these
580	# extra 3 octets anyway.	865	# few octets anyway.
581	syswrite $fh, "hi #$_\n";	866	syswrite $fh, "hi #$_\n";
582		867
583	# $fh is being closed here, as we don't store it anywhere	868	# $fh is being closed here, as we don't store it anywhere
584	});	869	});
585	}	870	}
…		…
587	# Some::function might look like this - all parameters passed before fork	872	# Some::function might look like this - all parameters passed before fork
588	# and after will be passed, in order, after the communications socket.	873	# and after will be passed, in order, after the communications socket.
589	sub Some::function {	874	sub Some::function {
590	my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_;	875	my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_;
591		876
592	print scalar <$fh>; # prints "hi 1\n" and "hi 2\n"	877	print scalar <$fh>; # prints "hi #1\n" and "hi #2\n" in any order
593	}	878	}
594		879
595	=cut	880	=cut
596		881
597	sub run {	882	sub run {
598	my ($self, $func, $cb) = @_;	883	my ($self, $func, $cb) = @_;
599		884
600	$self->[0] = $cb;	885	$self->[CB] = $cb;
601	$self->_cmd (r => $func);	886	$self->_cmd (r => $func);
602	}	887	}
		888
		889	=back
		890
		891	=head2 EXPERIMENTAL METHODS
		892
		893	These methods might go away completely or change behaviour, at any time.
		894
		895	=over 4
		896
		897	=item $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED
		898
		899	Flushes all commands out to the process and then calls the callback with
		900	the communications socket.
		901
		902	The process object becomes unusable on return from this function - any
		903	further method calls result in undefined behaviour.
		904
		905	The point of this method is to give you a file handle that you can pass
		906	to another process. In that other process, you can call C<new_from_fh
		907	AnyEvent::Fork $fh> to create a new C<AnyEvent::Fork> object from it,
		908	thereby effectively passing a fork object to another process.
		909
		910	=cut
		911
		912	sub to_fh {
		913	my ($self, $cb) = @_;
		914
		915	$self->[CB] = $cb;
		916
		917	unless ($self->[WW]) {
		918	$self->[CB]->($self->[FH]);
		919	@$self = ();
		920	}
		921	}
		922
		923	=item new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED
		924
		925	Takes a file handle originally rceeived by the C<to_fh> method and creates
		926	a new C<AnyEvent:Fork> object. The child process itself will not change in
		927	any way, i.e. it will keep all the modifications done to it before calling
		928	C<to_fh>.
		929
		930	The new object is very much like the original object, except that the
		931	C<pid> method will return C<undef> even if the process is a direct child.
		932
		933	=cut
		934
		935	sub new_from_fh {
		936	my ($class, $fh) = @_;
		937
		938	$class->_new ($fh)
		939	}
		940
		941	=back
		942
		943	=head1 PERFORMANCE
		944
		945	Now for some unscientific benchmark numbers (all done on an amd64
		946	GNU/Linux box). These are intended to give you an idea of the relative
		947	performance you can expect, they are not meant to be absolute performance
		948	numbers.
		949
		950	OK, so, I ran a simple benchmark that creates a socket pair, forks, calls
		951	exit in the child and waits for the socket to close in the parent. I did
		952	load AnyEvent, EV and AnyEvent::Fork, for a total process size of 5100kB.
		953
		954	2079 new processes per second, using manual socketpair + fork
		955
		956	Then I did the same thing, but instead of calling fork, I called
		957	AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the
		958	socket from the child to close on exit. This does the same thing as manual
		959	socket pair + fork, except that what is forked is the template process
		960	(2440kB), and the socket needs to be passed to the server at the other end
		961	of the socket first.
		962
		963	2307 new processes per second, using AnyEvent::Fork->new
		964
		965	And finally, using C<new_exec> instead C<new>, using vforks+execs to exec
		966	a new perl interpreter and compile the small server each time, I get:
		967
		968	479 vfork+execs per second, using AnyEvent::Fork->new_exec
		969
		970	So how can C<< AnyEvent->new >> be faster than a standard fork, even
		971	though it uses the same operations, but adds a lot of overhead?
		972
		973	The difference is simply the process size: forking the 5MB process takes
		974	so much longer than forking the 2.5MB template process that the extra
		975	overhead is canceled out.
		976
		977	If the benchmark process grows, the normal fork becomes even slower:
		978
		979	1340 new processes, manual fork of a 20MB process
		980	731 new processes, manual fork of a 200MB process
		981	235 new processes, manual fork of a 2000MB process
		982
		983	What that means (to me) is that I can use this module without having a bad
		984	conscience because of the extra overhead required to start new processes.
		985
		986	=head1 TYPICAL PROBLEMS
		987
		988	This section lists typical problems that remain. I hope by recognising
		989	them, most can be avoided.
		990
		991	=over 4
		992
		993	=item leaked file descriptors for exec'ed processes
		994
		995	POSIX systems inherit file descriptors by default when exec'ing a new
		996	process. While perl itself laudably sets the close-on-exec flags on new
		997	file handles, most C libraries don't care, and even if all cared, it's
		998	often not possible to set the flag in a race-free manner.
		999
		1000	That means some file descriptors can leak through. And since it isn't
		1001	possible to know which file descriptors are "good" and "necessary" (or
		1002	even to know which file descriptors are open), there is no good way to
		1003	close the ones that might harm.
		1004
		1005	As an example of what "harm" can be done consider a web server that
		1006	accepts connections and afterwards some module uses AnyEvent::Fork for the
		1007	first time, causing it to fork and exec a new process, which might inherit
		1008	the network socket. When the server closes the socket, it is still open
		1009	in the child (which doesn't even know that) and the client might conclude
		1010	that the connection is still fine.
		1011
		1012	For the main program, there are multiple remedies available -
		1013	L<AnyEvent::Fork::Early> is one, creating a process early and not using
		1014	C<new_exec> is another, as in both cases, the first process can be exec'ed
		1015	well before many random file descriptors are open.
		1016
		1017	In general, the solution for these kind of problems is to fix the
		1018	libraries or the code that leaks those file descriptors.
		1019
		1020	Fortunately, most of these leaked descriptors do no harm, other than
		1021	sitting on some resources.
		1022
		1023	=item leaked file descriptors for fork'ed processes
		1024
		1025	Normally, L<AnyEvent::Fork> does start new processes by exec'ing them,
		1026	which closes file descriptors not marked for being inherited.
		1027
		1028	However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer
		1029	a way to create these processes by forking, and this leaks more file
		1030	descriptors than exec'ing them, as there is no way to mark descriptors as
		1031	"close on fork".
		1032
		1033	An example would be modules like L<EV>, L<IO::AIO> or L<Gtk2>. Both create
		1034	pipes for internal uses, and L<Gtk2> might open a connection to the X
		1035	server. L<EV> and L<IO::AIO> can deal with fork, but Gtk2 might have
		1036	trouble with a fork.
		1037
		1038	The solution is to either not load these modules before use'ing
		1039	L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay
		1040	initialising them, for example, by calling C<init Gtk2> manually.
		1041
		1042	=item exiting calls object destructors
		1043
		1044	This only applies to users of L<AnyEvent::Fork:Early> and
		1045	L<AnyEvent::Fork::Template>, or when initialising code creates objects
		1046	that reference external resources.
		1047
		1048	When a process created by AnyEvent::Fork exits, it might do so by calling
		1049	exit, or simply letting perl reach the end of the program. At which point
		1050	Perl runs all destructors.
		1051
		1052	Not all destructors are fork-safe - for example, an object that represents
		1053	the connection to an X display might tell the X server to free resources,
		1054	which is inconvenient when the "real" object in the parent still needs to
		1055	use them.
		1056
		1057	This is obviously not a problem for L<AnyEvent::Fork::Early>, as you used
		1058	it as the very first thing, right?
		1059
		1060	It is a problem for L<AnyEvent::Fork::Template> though - and the solution
		1061	is to not create objects with nontrivial destructors that might have an
		1062	effect outside of Perl.
603		1063
604	=back	1064	=back
605		1065
606	=head1 PORTABILITY NOTES	1066	=head1 PORTABILITY NOTES
607		1067
608	Native win32 perls are somewhat supported (AnyEvent::Fork::Early is a nop,	1068	Native win32 perls are somewhat supported (AnyEvent::Fork::Early is a nop,
609	and ::Template is not going to work), and it cost a lot of blood and sweat	1069	and ::Template is not going to work), and it cost a lot of blood and sweat
610	to make it so, mostly due to the bloody broken perl that nobody seems to	1070	to make it so, mostly due to the bloody broken perl that nobody seems to
611	care about. The fork emulation is a bad joke - I have yet to see something	1071	care about. The fork emulation is a bad joke - I have yet to see something
612	useful that you cna do with it without running into memory corruption	1072	useful that you can do with it without running into memory corruption
613	issues or other braindamage. Hrrrr.	1073	issues or other braindamage. Hrrrr.
614		1074
615	Cygwin perl is not supported at the moment, as it should implement fd	1075	Since fork is endlessly broken on win32 perls (it doesn't even remotely
616	passing, but doesn't, and rolling my own is hard, as cygwin doesn't	1076	work within it's documented limits) and quite obviously it's not getting
617	support enough functionality to do it.	1077	improved any time soon, the best way to proceed on windows would be to
		1078	always use C<new_exec> and thus never rely on perl's fork "emulation".
618		1079
619	=head1 AUTHOR	1080	Cygwin perl is not supported at the moment due to some hilarious
		1081	shortcomings of its API - see L<IO::FDPoll> for more details. If you never
		1082	use C<send_fh> and always use C<new_exec> to create processes, it should
		1083	work though.
		1084
		1085	=head1 SEE ALSO
		1086
		1087	L<AnyEvent::Fork::Early>, to avoid executing a perl interpreter at all
		1088	(part of this distribution).
		1089
		1090	L<AnyEvent::Fork::Template>, to create a process by forking the main
		1091	program at a convenient time (part of this distribution).
		1092
		1093	L<AnyEvent::Fork::Remote>, for another way to create processes that is
		1094	mostly compatible to this module and modules building on top of it, but
		1095	works better with remote processes.
		1096
		1097	L<AnyEvent::Fork::RPC>, for simple RPC to child processes (on CPAN).
		1098
		1099	L<AnyEvent::Fork::Pool>, for simple worker process pool (on CPAN).
		1100
		1101	=head1 AUTHOR AND CONTACT INFORMATION
620		1102
621	Marc Lehmann <schmorp@schmorp.de>	1103	Marc Lehmann <schmorp@schmorp.de>
622	http://home.schmorp.de/	1104	http://software.schmorp.de/pkg/AnyEvent-Fork
623		1105
624	=cut	1106	=cut
625		1107
626	1	1108	1
627		1109

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Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.10 by root, Thu Apr 4 06:09:15 2013 UTC vs. Revision 1.59 by root, Fri Aug 30 12:06:48 2013 UTC

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Comparing AnyEvent-Fork/Fork.pm (file contents):
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Revision 1.59 by root, Fri Aug 30 12:06:48 2013 UTC