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

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.3 by root, Tue Apr 2 18:00:04 2013 UTC vs.
Revision 1.10 by root, Thu Apr 4 06:09:15 2013 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::ProcessPool - manage pools of perl worker processes, exec'ed or fork'ed	3	AnyEvent::Fork - everything you wanted to use fork() for, but couldn't
		4
		5	ATTENTION, this is a very early release, and very untested. Consider it a
		6	technology preview.
4		7
5	=head1 SYNOPSIS	8	=head1 SYNOPSIS
6		9
7	use AnyEvent::ProcessPool;	10	use AnyEvent::Fork;
		11
		12	##################################################################
		13	# create a single new process, tell it to run your worker function
		14
		15	AnyEvent::Fork
		16	->new
		17	->require ("MyModule")
		18	->run ("MyModule::worker, sub {
		19	my ($master_filehandle) = @_;
		20
		21	# now $master_filehandle is connected to the
		22	# $slave_filehandle in the new process.
		23	});
		24
		25	# MyModule::worker might look like this
		26	sub MyModule::worker {
		27	my ($slave_filehandle) = @_;
		28
		29	# now $slave_filehandle is connected to the $master_filehandle
		30	# in the original prorcess. have fun!
		31	}
		32
		33	##################################################################
		34	# create a pool of server processes all accepting on the same socket
		35
		36	# create listener socket
		37	my $listener = ...;
		38
		39	# create a pool template, initialise it and give it the socket
		40	my $pool = AnyEvent::Fork
		41	->new
		42	->require ("Some::Stuff", "My::Server")
		43	->send_fh ($listener);
		44
		45	# now create 10 identical workers
		46	for my $id (1..10) {
		47	$pool
		48	->fork
		49	->send_arg ($id)
		50	->run ("My::Server::run");
		51	}
		52
		53	# now do other things - maybe use the filehandle provided by run
		54	# to wait for the processes to die. or whatever.
		55
		56	# My::Server::run might look like this
		57	sub My::Server::run {
		58	my ($slave, $listener, $id) = @_;
		59
		60	close $slave; # we do not use the socket, so close it to save resources
		61
		62	# we could go ballistic and use e.g. AnyEvent here, or IO::AIO,
		63	# or anything we usually couldn't do in a process forked normally.
		64	while (my $socket = $listener->accept) {
		65	# do sth. with new socket
		66	}
		67	}
8		68
9	=head1 DESCRIPTION	69	=head1 DESCRIPTION
10		70
11	This module allows you to create single worker processes but also worker	71	This module allows you to create new processes, without actually forking
12	pool that share memory, by forking from the main program, or exec'ing new	72	them from your current process (avoiding the problems of forking), but
13	perl interpreters from a module.	73	preserving most of the advantages of fork.
14		74
15	You create a new processes in a pool by specifying a function to call	75	It can be used to create new worker processes or new independent
16	with any combination of string values and file handles.	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.
17		80
18	A pool can have initialisation code which is executed before forking. The	81	Special care has been taken to make this module useful from other modules,
19	initialisation code is only executed once and the resulting process is	82	while still supporting specialised environments such as L<App::Staticperl>
20	cached, to be used as a template.	83	or L<PAR::Packer>.
21
22	Pools without such initialisation code don't cache an extra process.
23		84
24	=head1 PROBLEM STATEMENT	85	=head1 PROBLEM STATEMENT
25		86
26	There are two ways to implement parallel processing on UNIX like operating	87	There are two ways to implement parallel processing on UNIX like operating
27	systems - fork and process, and fork+exec and process. They have different	88	systems - fork and process, and fork+exec and process. They have different
110	time, and the memory is not shared with anything else.	171	time, and the memory is not shared with anything else.
111		172
112	This is ideal for when you only need one extra process of a kind, with the	173	This is ideal for when you only need one extra process of a kind, with the
113	option of starting and stipping it on demand.	174	option of starting and stipping it on demand.
114		175
		176	Example:
		177
		178	AnyEvent::Fork
		179	->new
		180	->require ("Some::Module")
		181	->run ("Some::Module::run", sub {
		182	my ($fork_fh) = @_;
		183	});
		184
115	=item fork a new template process, load code, then fork processes off of	185	=item fork a new template process, load code, then fork processes off of
116	it and run the code	186	it and run the code
117		187
118	When you need to have a bunch of processes that all execute the same (or	188	When you need to have a bunch of processes that all execute the same (or
119	very similar) tasks, then a good way is to create a new template process	189	very similar) tasks, then a good way is to create a new template process
…		…
127	The disadvantage of this approach is that you need to create a template	197	The disadvantage of this approach is that you need to create a template
128	process for the sole purpose of forking new processes from it, but if you	198	process for the sole purpose of forking new processes from it, but if you
129	only need a fixed number of proceses you can create them, and then destroy	199	only need a fixed number of proceses you can create them, and then destroy
130	the template process.	200	the template process.
131		201
		202	Example:
		203
		204	my $template = AnyEvent::Fork->new->require ("Some::Module");
		205
		206	for (1..10) {
		207	$template->fork->run ("Some::Module::run", sub {
		208	my ($fork_fh) = @_;
		209	});
		210	}
		211
		212	# at this point, you can keep $template around to fork new processes
		213	# later, or you can destroy it, which causes it to vanish.
		214
132	=item execute a new perl interpreter, load some code, run it	215	=item execute a new perl interpreter, load some code, run it
133		216
134	This is relatively slow, and doesn't allow you to share memory between	217	This is relatively slow, and doesn't allow you to share memory between
135	multiple processes.	218	multiple processes.
136		219
137	The only advantage is that you don't have to have a template process	220	The only advantage is that you don't have to have a template process
138	hanging around all the time to fork off some new processes, which might be	221	hanging around all the time to fork off some new processes, which might be
139	an advantage when there are long time spans where no extra processes are	222	an advantage when there are long time spans where no extra processes are
140	needed.	223	needed.
141		224
		225	Example:
		226
		227	AnyEvent::Fork
		228	->new_exec
		229	->require ("Some::Module")
		230	->run ("Some::Module::run", sub {
		231	my ($fork_fh) = @_;
		232	});
		233
142	=back	234	=back
143		235
144	=head1 FUNCTIONS	236	=head1 FUNCTIONS
145		237
146	=over 4	238	=over 4
147		239
148	=cut	240	=cut
149		241
150	package AnyEvent::ProcessPool;	242	package AnyEvent::Fork;
151		243
152	use common::sense;	244	use common::sense;
153		245
154	use Socket ();	246	use Socket ();
155		247
156	use Proc::FastSpawn;
157	use AnyEvent;	248	use AnyEvent;
158	use AnyEvent::ProcessPool::Util;	249	use AnyEvent::Fork::Util;
159	use AnyEvent::Util ();	250	use AnyEvent::Util ();
160		251
161	BEGIN {	252	our $PERL; # the path to the perl interpreter, deduces with various forms of magic
162	# require Exporter;
163	}
164		253
165	=item my $pool = new AnyEvent::ProcessPool key => value...	254	=item my $pool = new AnyEvent::Fork key => value...
166		255
167	Create a new process pool. The following named parameters are supported:	256	Create a new process pool. The following named parameters are supported:
168		257
169	=over 4	258	=over 4
170		259
171	=back	260	=back
172		261
173	=cut	262	=cut
174		263
		264	# the early fork template process
		265	our $EARLY;
		266
175	# the template process	267	# the empty template process
176	our $template;	268	our $TEMPLATE;
177		269
178	sub _queue {	270	sub _cmd {
		271	my $self = shift;
		272
		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
		276	# from at least 5.8.9 to 5.16.3 are all buggy and can't unpack it.
		277	push @{ $self->[2] }, pack "N/a", pack "(w/a)*", @_;
		278
		279	$self->[3] \|\|= AE::io $self->[1], 1, sub {
		280	# send the next "thing" in the queue - either a reference to an fh,
		281	# or a plain string.
		282
		283	if (ref $self->[2][0]) {
		284	# send fh
		285	AnyEvent::Fork::Util::fd_send fileno $self->[1], fileno ${ $self->[2][0] }
		286	and shift @{ $self->[2] };
		287
		288	} else {
		289	# send string
		290	my $len = syswrite $self->[1], $self->[2][0]
		291	or do { undef $self->[3]; die "AnyEvent::Fork: command write failure: $!" };
		292
		293	substr $self->[2][0], 0, $len, "";
		294	shift @{ $self->[2] } unless length $self->[2][0];
		295	}
		296
		297	unless (@{ $self->[2] }) {
		298	undef $self->[3];
		299	# invoke run callback
		300	$self->[0]->($self->[1]) if $self->[0];
		301	}
		302	};
		303	}
		304
		305	sub _new {
179	my ($pid, $fh) = @_;	306	my ($self, $fh) = @_;
180		307
181	[	308	AnyEvent::Util::fh_nonblocking $fh, 1;
182	$pid,	309
		310	$self = bless [
		311	undef, # run callback
183	$fh,	312	$fh,
184	[],	313	[], # write queue - strings or fd's
185	undef	314	undef, # AE watcher
186	]	315	], $self;
187	}
188		316
189	sub queue_cmd {	317	$self
190	my $queue = shift;
191
192	push @{ $queue->[2] }, pack "N/a", pack "a (w/a)*", @_;
193
194	$queue->[3] \|\|= AE::io $queue->[1], 1, sub {
195	if (ref $queue->[2][0]) {
196	AnyEvent::ProcessPool::Util::fd_send fileno $queue->[1], fileno ${ $queue->[2][0] }
197	and shift @{ $queue->[2] };
198	} else {
199	my $len = syswrite $queue->[1], $queue->[2][0]
200	or do { undef $queue->[3]; die "AnyEvent::ProcessPool::queue write failure: $!" };
201	substr $queue->[2][0], 0, $len, "";
202	shift @{ $queue->[2] } unless length $queue->[2][0];
203	}
204
205	undef $queue->[3] unless @{ $queue->[2] };
206	};
207	}	318	}
208		319
209	sub run_template {	320	# fork template from current process, used by AnyEvent::Fork::Early/Template
210	return if $template;	321	sub _new_fork {
211
212	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;	322	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
213	AnyEvent::Util::fh_nonblocking $fh, 1;	323	my $parent = $$;
214	fd_inherit fileno $slave;
215		324
216	my %env = %ENV;	325	my $pid = fork;
217	$env{PERL5LIB} = join ":", grep !ref, @INC;
218		326
219	my $pid = spawn	327	if ($pid eq 0) {
220	$^X,	328	require AnyEvent::Fork::Serve;
221	["perl", "-MAnyEvent::ProcessPool::Serve", "-e", "AnyEvent::ProcessPool::Serve::me", fileno $slave],	329	$AnyEvent::Fork::Serve::OWNER = $parent;
222	[map "$_=$env{$_}", keys %env],	330	close $fh;
223	or die "unable to spawn AnyEvent::ProcessPool server: $!";	331	$0 = "$_[1] of $parent";
		332	AnyEvent::Fork::Serve::serve ($slave);
		333	AnyEvent::Fork::Util::_exit 0;
		334	} elsif (!$pid) {
		335	die "AnyEvent::Fork::Early/Template: unable to fork template process: $!";
		336	}
224		337
225	close $slave;	338	AnyEvent::Fork->_new ($fh)
226
227	$template = _queue $pid, $fh;
228
229	my ($a, $b) = AnyEvent::Util::portable_socketpair;
230
231	queue_cmd $template, "Iabc";
232	push @{ $template->[2] }, \$b;
233
234	use Coro::AnyEvent; Coro::AnyEvent::sleep 1;
235	undef $b;
236	die "x" . <$a>;
237	}	339	}
		340
		341	=item my $proc = new AnyEvent::Fork
		342
		343	Create a new "empty" perl interpreter process and returns its process
		344	object for further manipulation.
		345
		346	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
		348	C<new_exec> and kept 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
		355	=cut
238		356
239	sub new {	357	sub new {
240	my $class = shift;	358	my $class = shift;
241		359
242	my $self = bless {	360	$TEMPLATE \|\|= $class->new_exec;
243	@_	361	$TEMPLATE->fork
244	}, $class;	362	}
245		363
246	run_template;	364	=item $new_proc = $proc->fork
		365
		366	Forks C<$proc>, creating a new process, and returns the process object
		367	of the new process.
		368
		369	If any of the C<send_> functions have been called before fork, then they
		370	will be cloned in the child. For example, in a pre-forked server, you
		371	might C<send_fh> the listening socket into the template process, and then
		372	keep calling C<fork> and C<run>.
		373
		374	=cut
		375
		376	sub fork {
		377	my ($self) = @_;
		378
		379	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
		380
		381	$self->send_fh ($slave);
		382	$self->_cmd ("f");
		383
		384	AnyEvent::Fork->_new ($fh)
		385	}
		386
		387	=item my $proc = new_exec AnyEvent::Fork
		388
		389	Create a new "empty" perl interpreter process and returns its process
		390	object for further manipulation.
		391
		392	Unlike the C<new> method, this method I<always> spawns a new perl process
		393	(except in some cases, see L<AnyEvent::Fork::Early> for details). This
		394	reduces the amount of memory sharing that is possible, and is also slower.
		395
		396	You should use C<new> whenever possible, except when having a template
		397	process around is unacceptable.
		398
		399	The path to the perl interpreter is divined usign various methods - first
		400	C<$^X> is investigated to see if the path ends with something that sounds
		401	as if it were the perl interpreter. Failing this, the module falls back to
		402	using C<$Config::Config{perlpath}>.
		403
		404	=cut
		405
		406	sub new_exec {
		407	my ($self) = @_;
		408
		409	return $EARLY->fork
		410	if $EARLY;
		411
		412	# first find path of perl
		413	my $perl = $;
		414
		415	# 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
		417	unless (
		418	(AnyEvent::Fork::Util::WIN32 \|\| $perl =~ m%^/%)
		419	&& $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i
		420	) {
		421	# if it doesn't look perlish enough, try Config
		422	require Config;
		423	$perl = $Config::Config{perlpath};
		424	$perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/;
		425	}
		426
		427	require Proc::FastSpawn;
		428
		429	my ($fh, $slave) = AnyEvent::Util::portable_socketpair;
		430	Proc::FastSpawn::fd_inherit (fileno $slave);
		431
		432	# new fh's should always be set cloexec (due to $^F),
		433	# but hey, not on win32, so we always clear the inherit flag.
		434	Proc::FastSpawn::fd_inherit (fileno $fh, 0);
		435
		436	# quick. also doesn't work in win32. of course. what did you expect
		437	#local $ENV{PERL5LIB} = join ":", grep !ref, @INC;
		438	my %env = %ENV;
		439	$env{PERL5LIB} = join +(AnyEvent::Fork::Util::WIN32 ? ";" : ":"), grep !ref, @INC;
		440
		441	Proc::FastSpawn::spawn (
		442	$perl,
		443	["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$],
		444	[map "$_=$env{$_}", keys %env],
		445	) or die "unable to spawn AnyEvent::Fork server: $!";
		446
		447	$self->_new ($fh)
		448	}
		449
		450	=item $proc = $proc->eval ($perlcode, @args)
		451
		452	Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to
		453	the strings specified by C<@args>.
		454
		455	This call is meant to do any custom initialisation that might be required
		456	(for example, the C<require> method uses it). It's not supposed to be used
		457	to completely take over the process, use C<run> for that.
		458
		459	The code will usually be executed after this call returns, and there is no
		460	way to pass anything back to the calling process. Any evaluation errors
		461	will be reported to stderr and cause the process to exit.
		462
		463	Returns the process object for easy chaining of method calls.
		464
		465	=cut
		466
		467	sub eval {
		468	my ($self, $code, @args) = @_;
		469
		470	$self->_cmd (e => $code, @args);
247		471
248	$self	472	$self
249	}	473	}
250		474
		475	=item $proc = $proc->require ($module, ...)
		476
		477	Tries to load the given module(s) into the process
		478
		479	Returns the process object for easy chaining of method calls.
		480
		481	=cut
		482
		483	sub require {
		484	my ($self, @modules) = @_;
		485
		486	s%::%/%g for @modules;
		487	$self->eval ('require "$_.pm" for @_', @modules);
		488
		489	$self
		490	}
		491
		492	=item $proc = $proc->send_fh ($handle, ...)
		493
		494	Send one or more file handles (I<not> file descriptors) to the process,
		495	to prepare a call to C<run>.
		496
		497	The process object keeps a reference to the handles until this is done,
		498	so you must not explicitly close the handles. This is most easily
		499	accomplished by simply not storing the file handles anywhere after passing
		500	them to this method.
		501
		502	Returns the process object for easy chaining of method calls.
		503
		504	Example: pass an fh to a process, and release it without closing. it will
		505	be closed automatically when it is no longer used.
		506
		507	$proc->send_fh ($my_fh);
		508	undef $my_fh; # free the reference if you want, but DO NOT CLOSE IT
		509
		510	=cut
		511
		512	sub send_fh {
		513	my ($self, @fh) = @_;
		514
		515	for my $fh (@fh) {
		516	$self->_cmd ("h");
		517	push @{ $self->[2] }, \$fh;
		518	}
		519
		520	$self
		521	}
		522
		523	=item $proc = $proc->send_arg ($string, ...)
		524
		525	Send one or more argument strings to the process, to prepare a call to
		526	C<run>. The strings can be any octet string.
		527
		528	Returns the process object for easy chaining of emthod calls.
		529
		530	=cut
		531
		532	sub send_arg {
		533	my ($self, @arg) = @_;
		534
		535	$self->_cmd (a => @arg);
		536
		537	$self
		538	}
		539
		540	=item $proc->run ($func, $cb->($fh))
		541
		542	Enter the function specified by the fully qualified name in C<$func> in
		543	the process. The function is called with the communication socket as first
		544	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.
		546
		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.
		553
		554	If the communication socket isn't used, it should be closed on both sides,
		555	to save on kernel memory.
		556
		557	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
		559	otherwise, the socket can be a good indicator for the existance of the
		560	process - if the other process exits, you get a readable event on it,
		561	because exiting the process closes the socket (if it didn't create any
		562	children using fork).
		563
		564	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.
		566
		567	my $pool = AnyEvent::Fork
		568	->new
		569	->send_arg ("str1", "str2")
		570	->send_fh ($fh1, $fh2);
		571
		572	for (1..2) {
		573	$pool
		574	->fork
		575	->send_arg ("str3")
		576	->run ("Some::function", sub {
		577	my ($fh) = @_;
		578
		579	# fh is nonblocking, but we trust that the OS can accept these
		580	# extra 3 octets anyway.
		581	syswrite $fh, "hi #$_\n";
		582
		583	# $fh is being closed here, as we don't store it anywhere
		584	});
		585	}
		586
		587	# Some::function might look like this - all parameters passed before fork
		588	# and after will be passed, in order, after the communications socket.
		589	sub Some::function {
		590	my ($fh, $str1, $str2, $fh1, $fh2, $str3) = @_;
		591
		592	print scalar <$fh>; # prints "hi 1\n" and "hi 2\n"
		593	}
		594
		595	=cut
		596
		597	sub run {
		598	my ($self, $func, $cb) = @_;
		599
		600	$self->[0] = $cb;
		601	$self->_cmd (r => $func);
		602	}
		603
251	=back	604	=back
		605
		606	=head1 PORTABILITY NOTES
		607
		608	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
		610	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
		612	useful that you cna do with it without running into memory corruption
		613	issues or other braindamage. Hrrrr.
		614
		615	Cygwin perl is not supported at the moment, as it should implement fd
		616	passing, but doesn't, and rolling my own is hard, as cygwin doesn't
		617	support enough functionality to do it.
252		618
253	=head1 AUTHOR	619	=head1 AUTHOR
254		620
255	Marc Lehmann <schmorp@schmorp.de>	621	Marc Lehmann <schmorp@schmorp.de>
256	http://home.schmorp.de/	622	http://home.schmorp.de/

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.3 by root, Tue Apr 2 18:00:04 2013 UTC vs. Revision 1.10 by root, Thu Apr 4 06:09:15 2013 UTC

Diff Legend

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.3 by root, Tue Apr 2 18:00:04 2013 UTC vs.
Revision 1.10 by root, Thu Apr 4 06:09:15 2013 UTC