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

Comparing AnyEvent-Fork-Pool/Pool.pm (file contents):
Revision 1.2 by root, Thu Apr 18 21:37:27 2013 UTC vs.
Revision 1.12 by root, Sun Apr 28 14:26:11 2013 UTC

…		…
6		6
7	use AnyEvent;	7	use AnyEvent;
8	use AnyEvent::Fork::Pool;	8	use AnyEvent::Fork::Pool;
9	# use AnyEvent::Fork is not needed	9	# use AnyEvent::Fork is not needed
10		10
11	# all parameters with default values	11	# all possible parameters shown, with default values
12	my $pool = new AnyEvent::Fork::Pool	12	my $pool = AnyEvent::Fork
13	"MyWorker::run",	13	->new
		14	->require ("MyWorker")
		15	->AnyEvent::Fork::Pool::run (
		16	"MyWorker::run", # the worker function
14		17
15	# pool management	18	# pool management
16	min => 0, # minimum # of processes
17	max => 4, # maximum # of processes	19	max => 4, # absolute maximum # of processes
18	max_queue => 2, # queue at most this number of jobs per process	20	idle => 0, # minimum # of idle processes
		21	load => 2, # queue at most this number of jobs per process
19	min_delay => 0, # wait this many seconds before starting a new process	22	start => 0.1, # wait this many seconds before starting a new process
20	min_idle => 0, # try to have at least this amount of idle processes
21	max_idle => 1, # at most this many idle processes
22	idle_time => 1, # wait this many seconds before killing an idle process	23	stop => 10, # wait this many seconds before stopping an idle process
23	on_destroy => (my $finish = AE::cv),	24	on_destroy => (my $finish = AE::cv), # called when object is destroyed
24		25
25	# template process
26	template => AnyEvent::Fork->new, # the template process to use
27	require => [MyWorker::], # module(s) to load
28	eval => "# perl code to execute in template",
29
30	# parameters passed to AnyEvent::Fork::RPC	26	# parameters passed to AnyEvent::Fork::RPC
31	async => 0,	27	async => 0,
32	on_error => sub { die "FATAL: $_[0]\n" },	28	on_error => sub { die "FATAL: $_[0]\n" },
33	on_event => sub { my @ev = @_ },	29	on_event => sub { my @ev = @_ },
34	init => "MyWorker::init",	30	init => "MyWorker::init",
35	serialiser => $AnyEvent::Fork::RPC::STRING_SERIALISER,	31	serialiser => $AnyEvent::Fork::RPC::STRING_SERIALISER,
36	;	32	);
37		33
38	for (1..10) {	34	for (1..10) {
39	$pool->call (doit => $_, sub {	35	$pool->(doit => $_, sub {
40	print "MyWorker::run returned @_\n";	36	print "MyWorker::run returned @_\n";
41	});	37	});
42	}	38	}
43		39
44	undef $pool;	40	undef $pool;
45		41
46	$finish->recv;	42	$finish->recv;
47		43
48	=head1 DESCRIPTION	44	=head1 DESCRIPTION
49		45
50	This module uses processes created via L<AnyEvent::Fork> and the RPC	46	This module uses processes created via L<AnyEvent::Fork> (or
51	protocol implement in L<AnyEvent::Fork::RPC> to create a load-balanced	47	L<AnyEvent::Fork::Remote>) and the RPC protocol implement in
52	pool of processes that handles jobs.	48	L<AnyEvent::Fork::RPC> to create a load-balanced pool of processes that
		49	handles jobs.
53		50
54	Understanding of L<AnyEvent::Fork> is helpful but not critical to be able	51	Understanding of L<AnyEvent::Fork> is helpful but not critical to be able
55	to use this module, but a thorough understanding of L<AnyEvent::Fork::RPC>	52	to use this module, but a thorough understanding of L<AnyEvent::Fork::RPC>
56	is, as it defines the actual API that needs to be implemented in the	53	is, as it defines the actual API that needs to be implemented in the
57	children.	54	worker processes.
58
59	=head1 EXAMPLES
60		55
61	=head1 PARENT USAGE	56	=head1 PARENT USAGE
62		57
		58	To create a pool, you first have to create a L<AnyEvent::Fork> object -
		59	this object becomes your template process. Whenever a new worker process
		60	is needed, it is forked from this template process. Then you need to
		61	"hand off" this template process to the C<AnyEvent::Fork::Pool> module by
		62	calling its run method on it:
		63
		64	my $template = AnyEvent::Fork
		65	->new
		66	->require ("SomeModule", "MyWorkerModule");
		67
		68	my $pool = $template->AnyEvent::Fork::Pool::run ("MyWorkerModule::myfunction");
		69
		70	The pool "object" is not a regular Perl object, but a code reference that
		71	you can call and that works roughly like calling the worker function
		72	directly, except that it returns nothing but instead you need to specify a
		73	callback to be invoked once results are in:
		74
		75	$pool->(1, 2, 3, sub { warn "myfunction(1,2,3) returned @_" });
		76
63	=over 4	77	=over 4
64		78
65	=cut	79	=cut
66		80
67	package AnyEvent::Fork::Pool;	81	package AnyEvent::Fork::Pool;
68		82
69	use common::sense;	83	use common::sense;
70		84
71	use Scalar::Util ();	85	use Scalar::Util ();
72		86
		87	use Guard ();
73	use Array::Heap ();	88	use Array::Heap ();
74		89
75	use AnyEvent;	90	use AnyEvent;
		91	# explicit version on next line, as some cpan-testers test with the 0.1 version,
		92	# ignoring dependencies, and this line will at least give a clear indication of that.
76	use AnyEvent::Fork; # we don't actually depend on it, this is for convenience	93	use AnyEvent::Fork 0.6; # we don't actually depend on it, this is for convenience
77	use AnyEvent::Fork::RPC;	94	use AnyEvent::Fork::RPC;
78		95
		96	# these are used for the first and last argument of events
		97	# in the hope of not colliding. yes, I don't like it either,
		98	# but didn't come up with an obviously better alternative.
79	my $magic0 = ':t6Z@HK1N%Dx@_7?=~-7NQgWDdAs6a,jFN=wLO0jD1%P';	99	my $magic0 = ':t6Z@HK1N%Dx@_7?=~-7NQgWDdAs6a,jFN=wLO0jD1%P';
80	my $magic2 = '<~53rexz.U`!]X[A235^"fyEoiTF\T~oH1l/N6+Djep9b~bI9`\1x%B~vWO1q*';	100	my $magic1 = '<~53rexz.U`!]X[A235^"fyEoiTF\T~oH1l/N6+Djep9b~bI9`\1x%B~vWO1q*';
81		101
82	our $VERSION = 0.1;	102	our $VERSION = 1.1;
83		103
84	=item my $rpc = new AnyEvent::Fork::Pool $function, [key => value...]	104	=item my $pool = AnyEvent::Fork::Pool::run $fork, $function, [key => value...]
		105
		106	The traditional way to call the pool creation function. But it is way
		107	cooler to call it in the following way:
		108
		109	=item my $pool = $fork->AnyEvent::Fork::Pool::run ($function, [key => value...])
85		110
86	Creates a new pool object with the specified C<$function> as function	111	Creates a new pool object with the specified C<$function> as function
87	(name) to call for each request.	112	(name) to call for each request. The pool uses the C<$fork> object as the
88		113	template when creating worker processes.
89	A pool consists of a template process that contains the code and data that
90	the worker processes need. And a number of worker processes that have been
91	forked off of that template process.
92		114
93	You can supply your own template process, or tell C<AnyEvent::Fork::Pool>	115	You can supply your own template process, or tell C<AnyEvent::Fork::Pool>
94	to create one.	116	to create one.
95		117
96	A relatively large number of key/value pairs can be specified to influence	118	A relatively large number of key/value pairs can be specified to influence
…		…
101		123
102	=item Pool Management	124	=item Pool Management
103		125
104	The pool consists of a certain number of worker processes. These options	126	The pool consists of a certain number of worker processes. These options
105	decide how many of these processes exist and when they are started and	127	decide how many of these processes exist and when they are started and
106	stopp.ed	128	stopped.
		129
		130	The worker pool is dynamically resized, according to (perceived :)
		131	load. The minimum size is given by the C<idle> parameter and the maximum
		132	size is given by the C<max> parameter. A new worker is started every
		133	C<start> seconds at most, and an idle worker is stopped at most every
		134	C<stop> second.
		135
		136	You can specify the amount of jobs sent to a worker concurrently using the
		137	C<load> parameter.
107		138
108	=over 4	139	=over 4
109		140
110	=item min => $count (default: 0)	141	=item idle => $count (default: 0)
111		142
112	The minimum number of processes in the pool, in addition to the template	143	The minimum amount of idle processes in the pool - when there are fewer
113	process. Even when idle, there will never be fewer than this number of	144	than this many idle workers, C<AnyEvent::Fork::Pool> will try to start new
114	worker processes. The default means that the pool can be empty.	145	ones, subject to the limits set by C<max> and C<start>.
		146
		147	This is also the initial amount of workers in the pool. The default of
		148	zero means that the pool starts empty and can shrink back to zero workers
		149	over time.
115		150
116	=item max => $count (default: 4)	151	=item max => $count (default: 4)
117		152
118	The maximum number of processes in the pool, in addition to the template	153	The maximum number of processes in the pool, in addition to the template
119	process. C<AnyEvent::Fork::Pool> will never create more than this number	154	process. C<AnyEvent::Fork::Pool> will never have more than this number of
120	of processes.	155	worker processes, although there can be more temporarily when a worker is
		156	shut down and hasn't exited yet.
121		157
122	=item max_queue => $count (default: 2)	158	=item load => $count (default: 2)
123		159
124	The maximum number of jobs sent to a single worker process. Worker	160	The maximum number of concurrent jobs sent to a single worker process.
125	processes that handle this number of jobs already are called "busy".
126		161
127	Jobs that cannot be sent to a worker immediately (because all workers are	162	Jobs that cannot be sent to a worker immediately (because all workers are
128	busy) will be queued until a worker is available.	163	busy) will be queued until a worker is available.
129		164
		165	Setting this low improves latency. For example, at C<1>, every job that
		166	is sent to a worker is sent to a completely idle worker that doesn't run
		167	any other jobs. The downside is that throughput is reduced - a worker that
		168	finishes a job needs to wait for a new job from the parent.
		169
		170	The default of C<2> is usually a good compromise.
		171
130	=item min_delay => $seconds (default: 0)	172	=item start => $seconds (default: 0.1)
131		173
132	When a job is queued and all workers are busy, a timer is started. If the	174	When there are fewer than C<idle> workers (or all workers are completely
133	timer elapses and there are still jobs that cannot be queued to a worker,	175	busy), then a timer is started. If the timer elapses and there are still
134	a new worker is started.	176	jobs that cannot be queued to a worker, a new worker is started.
135		177
136	This configurs the time that all workers must be busy before a new worker	178	This sets the minimum time that all workers must be busy before a new
137	is started. Or, put differently, the minimum delay betwene starting new	179	worker is started. Or, put differently, the minimum delay between starting
138	workers.	180	new workers.
139		181
140	The delay is zero by default, which means new workers will be started	182	The delay is small by default, which means new workers will be started
141	without delay.	183	relatively quickly. A delay of C<0> is possible, and ensures that the pool
		184	will grow as quickly as possible under load.
142		185
143	=item min_idle => $count (default: 0)	186	Non-zero values are useful to avoid "exploding" a pool because a lot of
		187	jobs are queued in an instant.
144		188
145	The minimum number of idle workers - when they are less, more	189	Higher values are often useful to improve efficiency at the cost of
146	are started. The C<min_delay> is still respected though, and	190	latency - when fewer processes can do the job over time, starting more and
147	C<min_idle>/C<min_delay> and C<max_idle>/C<idle_time> are useful to	191	more is not necessarily going to help.
148	dynamically adjust the pool.
149		192
150	=item max_idle => $count (default: 1)
151
152	The maximum number of idle workers. If a worker becomes idle and there are
153	already this many idle workers, it will be stopped immediately instead of
154	waiting for the idle timer to elapse.
155
156	=item idle_time => $seconds (default: 1)	193	=item stop => $seconds (default: 10)
157		194
158	When a worker has no jobs to execute it becomes idle. An idle worker that	195	When a worker has no jobs to execute it becomes idle. An idle worker that
159	hasn't executed a job within this amount of time will be stopped, unless	196	hasn't executed a job within this amount of time will be stopped, unless
160	the other parameters say otherwise.	197	the other parameters say otherwise.
161		198
		199	Setting this to a very high value means that workers stay around longer,
		200	even when they have nothing to do, which can be good as they don't have to
		201	be started on the netx load spike again.
		202
		203	Setting this to a lower value can be useful to avoid memory or simply
		204	process table wastage.
		205
		206	Usually, setting this to a time longer than the time between load spikes
		207	is best - if you expect a lot of requests every minute and little work
		208	in between, setting this to longer than a minute avoids having to stop
		209	and start workers. On the other hand, you have to ask yourself if letting
		210	workers run idle is a good use of your resources. Try to find a good
		211	balance between resource usage of your workers and the time to start new
		212	workers - the processes created by L<AnyEvent::Fork> itself is fats at
		213	creating workers while not using much memory for them, so most of the
		214	overhead is likely from your own code.
		215
162	=item on_destroy => $callback->() (default: none)	216	=item on_destroy => $callback->() (default: none)
163		217
164	When a pool object goes out of scope, it will still handle all outstanding	218	When a pool object goes out of scope, the outstanding requests are still
165	jobs. After that, it will destroy all workers (and also the template	219	handled till completion. Only after handling all jobs will the workers
166	process if it isn't referenced otherwise).	220	be destroyed (and also the template process if it isn't referenced
		221	otherwise).
		222
		223	To find out when a pool I<really> has finished its work, you can set this
		224	callback, which will be called when the pool has been destroyed.
167		225
168	=back	226	=back
169		227
170	=item Template Process	228	=item AnyEvent::Fork::RPC Parameters
171		229
172	The worker processes are all forked from a single template	230	These parameters are all passed more or less directly to
173	process. Ideally, all modules and all cdoe used by the worker, as well as	231	L<AnyEvent::Fork::RPC>. They are only briefly mentioned here, for
174	any shared data structures should be loaded into the template process, to	232	their full documentation please refer to the L<AnyEvent::Fork::RPC>
175	take advantage of data sharing via fork.	233	documentation. Also, the default values mentioned here are only documented
176		234	as a best effort - the L<AnyEvent::Fork::RPC> documentation is binding.
177	You can create your own template process by creating a L<AnyEvent::Fork>
178	object yourself and passing it as the C<template> parameter, but
179	C<AnyEvent::Fork::Pool> can create one for you, including some standard
180	options.
181		235
182	=over 4	236	=over 4
183		237
184	=item template => $fork (default: C<< AnyEvent::Fork->new >>)	238	=item async => $boolean (default: 0)
185		239
186	The template process to use, if you want to create your own.	240	Whether to use the synchronous or asynchronous RPC backend.
187		241
188	=item require => \@modules (default: C<[]>)	242	=item on_error => $callback->($message) (default: die with message)
189		243
190	The modules in this list will be laoded into the template process.	244	The callback to call on any (fatal) errors.
191		245
192	=item eval => "# perl code to execute in template" (default: none)	246	=item on_event => $callback->(...) (default: C<sub { }>, unlike L<AnyEvent::Fork::RPC>)
193		247
194	This is a perl string that is evaluated after creating the template	248	The callback to invoke on events.
195	process and after requiring the modules. It can do whatever it wants to	249
196	configure the process, but it must not do anything that would keep a later	250	=item init => $initfunction (default: none)
197	fork from working (so must not create event handlers or (real) threads for	251
198	example).	252	The function to call in the child, once before handling requests.
		253
		254	=item serialiser => $serialiser (defailt: $AnyEvent::Fork::RPC::STRING_SERIALISER)
		255
		256	The serialiser to use.
199		257
200	=back	258	=back
201		259
202	=item AnyEvent::Fork::RPC Parameters
203
204	These parameters are all passed directly to L<AnyEvent::Fork::RPC>. They
205	are only briefly mentioned here, for their full documentation
206	please refer to the L<AnyEvent::Fork::RPC> documentation. Also, the
207	default values mentioned here are only documented as a best effort -
208	L<AnyEvent::Fork::RPC> documentation is binding.
209
210	=over 4
211
212	=item async => $boolean (default: 0)
213
214	Whether to sue the synchronous or asynchronous RPC backend.
215
216	=item on_error => $callback->($message) (default: die with message)
217
218	The callback to call on any (fatal) errors.
219
220	=item on_event => $callback->(...) (default: C<sub { }>, unlike L<AnyEvent::Fork::RPC>)
221
222	The callback to invoke on events.
223
224	=item init => $initfunction (default: none)
225
226	The function to call in the child, once before handling requests.
227
228	=item serialiser => $serialiser (defailt: $AnyEvent::Fork::RPC::STRING_SERIALISER)
229
230	The serialiser to use.
231
232	=back	260	=back
233		261
234	=back
235
236	=cut	262	=cut
237		263
238	sub new {	264	sub run {
239	my ($class, $function, %arg) = @_;	265	my ($template, $function, %arg) = @_;
240		266
241	my $self = bless {	267	my $max = $arg{max} \|\| 4;
242	min => 0,	268	my $idle = $arg{idle} \|\| 0,
243	max => 4,	269	my $load = $arg{load} \|\| 2,
244	max_queue => 2,	270	my $start = $arg{start} \|\| 0.1,
245	min_delay => 0,	271	my $stop = $arg{stop} \|\| 10,
246	max_idle => 1,	272	my $on_event = $arg{on_event} \|\| sub { },
247	idle_time => 1,	273	my $on_destroy = $arg{on_destroy};
248	on_event => sub { },
249	%arg,
250	pool => [],
251	queue => [],
252	}, $class;
253		274
254	$self->{function} = $function;	275	my @rpc = (
		276	async => $arg{async},
		277	init => $arg{init},
		278	serialiser => delete $arg{serialiser},
		279	on_error => $arg{on_error},
		280	);
255		281
256	($self->{template} \|\|= new AnyEvent::Fork)	282	my (@pool, @queue, $nidle, $start_w, $stop_w, $shutdown);
		283	my ($start_worker, $stop_worker, $want_start, $want_stop, $scheduler);
		284
		285	my $destroy_guard = Guard::guard {
		286	$on_destroy->()
		287	if $on_destroy;
		288	};
		289
		290	$template
257	->require ("AnyEvent::Fork::RPC::" . ($self->{async} ? "Async" : "Sync"))	291	->require ("AnyEvent::Fork::RPC::" . ($arg{async} ? "Async" : "Sync"))
258	->require (@{ delete $self->{require} })
259	->eval ('	292	->eval ('
260	my ($magic0, $magic2) = @_;	293	my ($magic0, $magic1) = @_;
261	sub AnyEvent::Fork::Pool::quit() {	294	sub AnyEvent::Fork::Pool::retire() {
262	AnyEvent::Fork::RPC::on_event $magic0, "quit", $magic2;	295	AnyEvent::Fork::RPC::event $magic0, "quit", $magic1;
263	}	296	}
264	', $magic0, $magic2)	297	', $magic0, $magic1)
265	->eval (delete $self->{eval});	298	;
266		299
267	$self->start	300	$start_worker = sub {
268	while @{ $self->{pool} } < $self->{min};	301	my $proc = [0, 0, undef]; # load, index, rpc
269		302
270	$self	303	$proc->[2] = $template
		304	->fork
		305	->AnyEvent::Fork::RPC::run ($function,
		306	@rpc,
		307	on_event => sub {
		308	if (@_ == 3 && $_[0] eq $magic0 && $_[2] eq $magic1) {
		309	$destroy_guard if 0; # keep it alive
		310
		311	$_[1] eq "quit" and $stop_worker->($proc);
		312	return;
		313	}
		314
		315	&$on_event;
		316	},
		317	)
		318	;
		319
		320	++$nidle;
		321	Array::Heap::push_heap_idx @pool, $proc;
		322
		323	Scalar::Util::weaken $proc;
		324	};
		325
		326	$stop_worker = sub {
		327	my $proc = shift;
		328
		329	$proc->[0]
		330	or --$nidle;
		331
		332	Array::Heap::splice_heap_idx @pool, $proc->[1]
		333	if defined $proc->[1];
		334
		335	@$proc = 0; # tell others to leave it be
		336	};
		337
		338	$want_start = sub {
		339	undef $stop_w;
		340
		341	$start_w \|\|= AE::timer $start, $start, sub {
		342	if (($nidle < $idle \|\| @queue) && @pool < $max) {
		343	$start_worker->();
		344	$scheduler->();
		345	} else {
		346	undef $start_w;
		347	}
		348	};
		349	};
		350
		351	$want_stop = sub {
		352	$stop_w \|\|= AE::timer $stop, $stop, sub {
		353	$stop_worker->($pool[0])
		354	if $nidle;
		355
		356	undef $stop_w
		357	if $nidle <= $idle;
		358	};
		359	};
		360
		361	$scheduler = sub {
		362	if (@queue) {
		363	while (@queue) {
		364	@pool or $start_worker->();
		365
		366	my $proc = $pool[0];
		367
		368	if ($proc->[0] < $load) {
		369	# found free worker, increase load
		370	unless ($proc->[0]++) {
		371	# worker became busy
		372	--$nidle
		373	or undef $stop_w;
		374
		375	$want_start->()
		376	if $nidle < $idle && @pool < $max;
		377	}
		378
		379	Array::Heap::adjust_heap_idx @pool, 0;
		380
		381	my $job = shift @queue;
		382	my $ocb = pop @$job;
		383
		384	$proc->[2]->(@$job, sub {
		385	# reduce load
		386	--$proc->[0] # worker still busy?
		387	or ++$nidle > $idle # not too many idle processes?
		388	or $want_stop->();
		389
		390	Array::Heap::adjust_heap_idx @pool, $proc->[1]
		391	if defined $proc->[1];
		392
		393	&$ocb;
		394
		395	$scheduler->();
		396	});
		397	} else {
		398	$want_start->()
		399	unless @pool >= $max;
		400
		401	last;
		402	}
		403	}
		404	} elsif ($shutdown) {
		405	@pool = ();
		406	undef $start_w;
		407	undef $start_worker; # frees $destroy_guard reference
		408
		409	$stop_worker->($pool[0])
		410	while $nidle;
		411	}
		412	};
		413
		414	my $shutdown_guard = Guard::guard {
		415	$shutdown = 1;
		416	$scheduler->();
		417	};
		418
		419	$start_worker->()
		420	while @pool < $idle;
		421
		422	sub {
		423	$shutdown_guard if 0; # keep it alive
		424
		425	$start_worker->()
		426	unless @pool;
		427
		428	push @queue, [@_];
		429	$scheduler->();
		430	}
271	}	431	}
272		432
273	sub start {
274	my ($self) = @_;
275
276	warn "start\n";#d#
277
278	Scalar::Util::weaken $self;
279
280	my $proc = [0, undef, undef];
281
282	$proc->[1] = $self->{template}
283	->fork
284	->AnyEvent::Fork::RPC::run ($self->{function},
285	async => $self->{async},
286	init => $self->{init},
287	serialiser => $self->{serialiser},
288	on_error => $self->{on_error},
289	on_event => sub {
290	if (@_ == 3 && $_[0] eq $magic0 && $_[2] eq $magic2) {
291	if ($_[1] eq "quit") {
292	my $pool = $self->{pool};
293	for (0 .. $#$pool) {
294	if ($pool->[$_] == $proc) {
295	Array::Heap::splice_heap @$pool, $_;
296	return;
297	}
298	}
299	die;
300	}
301	return;
302	}
303
304	&{ $self->{on_event} };
305	},
306	)
307	;
308
309	++$self->{idle};
310	Array::Heap::push_heap @{ $self->{pool} }, $proc;
311	}
312
313	=item $pool->call (..., $cb->(...))	433	=item $pool->(..., $cb->(...))
314		434
315	Call the RPC function of a worker with the given arguments, and when the	435	Call the RPC function of a worker with the given arguments, and when the
316	worker is done, call the C<$cb> with the results, like just calling the	436	worker is done, call the C<$cb> with the results, just like calling the
317	L<AnyEvent::Fork::RPC> object directly.	437	RPC object durectly - see the L<AnyEvent::Fork::RPC> documentation for
		438	details on the RPC API.
318		439
319	If there is no free worker, the call will be queued.	440	If there is no free worker, the call will be queued until a worker becomes
		441	available.
320		442
321	Note that there can be considerable time between calling this method and	443	Note that there can be considerable time between calling this method and
322	the call actually being executed. During this time, the parameters passed	444	the call actually being executed. During this time, the parameters passed
323	to this function are effectively read-only - modifying them after the call	445	to this function are effectively read-only - modifying them after the call
324	and before the callback is invoked causes undefined behaviour.	446	and before the callback is invoked causes undefined behaviour.
325		447
326	=cut	448	=cut
327		449
328	sub scheduler {	450	=item $cpus = AnyEvent::Fork::Pool::ncpu [$default_cpus]
329	my $self = shift;
330		451
331	my $pool = $self->{pool};	452	=item ($cpus, $eus) = AnyEvent::Fork::Pool::ncpu [$default_cpus]
332	my $queue = $self->{queue};
333		453
334	$self->start	454	Tries to detect the number of CPUs (C<$cpus> often called cpu cores
335	unless @$pool;	455	nowadays) and execution units (C<$eus>) which include e.g. extra
		456	hyperthreaded units). When C<$cpus> cannot be determined reliably,
		457	C<$default_cpus> is returned for both values, or C<1> if it is missing.
336		458
337	while (@$queue) {	459	For normal CPU bound uses, it is wise to have as many worker processes
338	my $proc = $pool->[0];	460	as CPUs in the system (C<$cpus>), if nothing else uses the CPU. Using
		461	hyperthreading is usually detrimental to performance, but in those rare
		462	cases where that really helps it might be beneficial to use more workers
		463	(C<$eus>).
339		464
340	if ($proc->[0] < $self->{max_queue}) {	465	Currently, F</proc/cpuinfo> is parsed on GNU/Linux systems for both
341	warn "free $proc $proc->[0]\n";#d#	466	C<$cpus> and C<$eu>, and on {Free,Net,Open}BSD, F<sysctl -n hw.ncpu> is
342	# found free worker	467	used for C<$cpus>.
343	--$self->{idle}
344	unless $proc->[0]++;
345		468
346	undef $proc->[2];	469	Example: create a worker pool with as many workers as cpu cores, or C<2>,
		470	if the actual number could not be determined.
347		471
348	Array::Heap::adjust_heap @$pool, 0;	472	$fork->AnyEvent::Fork::Pool::run ("myworker::function",
		473	max => (scalar AnyEvent::Fork::Pool::ncpu 2),
		474	);
349		475
350	my $job = shift @$queue;	476	=cut
351	my $ocb = pop @$job;
352		477
353	$proc->[1]->(@$job, sub {	478	BEGIN {
354	for (0 .. $#$pool) {	479	if ($^O eq "linux") {
355	if ($pool->[$_] == $proc) {	480	*ncpu = sub(;$) {
356	# reduce queue counter	481	my ($cpus, $eus);
357	unless (--$pool->[$_][0]) {
358	# worker becomes idle
359	my $to = ++$self->{idle} > $self->{max_idle}
360	? 0
361	: $self->{idle_time};
362		482
363	$proc->[2] = AE::timer $to, 0, sub {	483	if (open my $fh, "<", "/proc/cpuinfo") {
364	undef $proc->[2];	484	my %id;
365		485
366	warn "destroy $proc afzer $to\n";#d#	486	while (<$fh>) {
367		487	if (/^core id\s:\s(\d+)/) {
368	for (0 .. $#$pool) {
369	if ($pool->[$_] == $proc) {
370	Array::Heap::splice_heap @$pool, $_;
371	--$self->{idle};
372	last;
373	}
374	}
375	};
376	}
377
378	Array::Heap::adjust_heap @$pool, $_;
379	last;	488	++$eus;
		489	undef $id{$1};
380	}	490	}
381	}	491	}
382	&$ocb;	492
383	});	493	$cpus = scalar keys %id;
384	} else {	494	} else {
385	warn "busy $proc->[0]\n";#d#	495	$cpus = $eus = @_ ? shift : 1;
386	# all busy, delay
387
388	$self->{min_delay_w} \|\|= AE::timer $self->{min_delay}, 0, sub {
389	delete $self->{min_delay_w};
390
391	if (@{ $self->{queue} }) {
392	$self->start;
393	$self->scheduler;
394	}
395	};	496	}
396	last;	497	wantarray ? ($cpus, $eus) : $cpus
397	}	498	};
		499	} elsif ($^O eq "freebsd" \|\| $^O eq "netbsd" \|\| $^O eq "openbsd") {
		500	*ncpu = sub(;$) {
		501	my $cpus = qx<sysctl -n hw.ncpu> * 1
		502	\|\| (@_ ? shift : 1);
		503	wantarray ? ($cpus, $cpus) : $cpus
		504	};
		505	} else {
		506	*ncpu = sub(;$) {
		507	my $cpus = @_ ? shift : 1;
		508	wantarray ? ($cpus, $cpus) : $cpus
		509	};
398	}	510	}
399	warn "last\n";#d#
400	}	511	}
401		512
402	sub call {
403	my $self = shift;
404
405	push @{ $self->{queue} }, [@_];
406	$self->scheduler;
407	}
408
409	sub DESTROY {
410	$_[0]{on_destroy}->();
411	}
412
413	=back	513	=back
		514
		515	=head1 CHILD USAGE
		516
		517	In addition to the L<AnyEvent::Fork::RPC> API, this module implements one
		518	more child-side function:
		519
		520	=over 4
		521
		522	=item AnyEvent::Fork::Pool::retire ()
		523
		524	This function sends an event to the parent process to request retirement:
		525	the worker is removed from the pool and no new jobs will be sent to it,
		526	but it has to handle the jobs that are already queued.
		527
		528	The parentheses are part of the syntax: the function usually isn't defined
		529	when you compile your code (because that happens I<before> handing the
		530	template process over to C<AnyEvent::Fork::Pool::run>, so you need the
		531	empty parentheses to tell Perl that the function is indeed a function.
		532
		533	Retiring a worker can be useful to gracefully shut it down when the worker
		534	deems this useful. For example, after executing a job, one could check
		535	the process size or the number of jobs handled so far, and if either is
		536	too high, the worker could ask to get retired, to avoid memory leaks to
		537	accumulate.
		538
		539	Example: retire a worker after it has handled roughly 100 requests.
		540
		541	my $count = 0;
		542
		543	sub my::worker {
		544
		545	++$count == 100
		546	and AnyEvent::Fork::Pool::retire ();
		547
		548	... normal code goes here
		549	}
		550
		551	=back
		552
		553	=head1 POOL PARAMETERS RECIPES
		554
		555	This section describes some recipes for pool paramaters. These are mostly
		556	meant for the synchronous RPC backend, as the asynchronous RPC backend
		557	changes the rules considerably, making workers themselves responsible for
		558	their scheduling.
		559
		560	=over 4
		561
		562	=item low latency - set load = 1
		563
		564	If you need a deterministic low latency, you should set the C<load>
		565	parameter to C<1>. This ensures that never more than one job is sent to
		566	each worker. This avoids having to wait for a previous job to finish.
		567
		568	This makes most sense with the synchronous (default) backend, as the
		569	asynchronous backend can handle multiple requests concurrently.
		570
		571	=item lowest latency - set load = 1 and idle = max
		572
		573	To achieve the lowest latency, you additionally should disable any dynamic
		574	resizing of the pool by setting C<idle> to the same value as C<max>.
		575
		576	=item high throughput, cpu bound jobs - set load >= 2, max = #cpus
		577
		578	To get high throughput with cpu-bound jobs, you should set the maximum
		579	pool size to the number of cpus in your system, and C<load> to at least
		580	C<2>, to make sure there can be another job waiting for the worker when it
		581	has finished one.
		582
		583	The value of C<2> for C<load> is the minimum value that I<can> achieve
		584	100% throughput, but if your parent process itself is sometimes busy, you
		585	might need higher values. Also there is a limit on the amount of data that
		586	can be "in flight" to the worker, so if you send big blobs of data to your
		587	worker, C<load> might have much less of an effect.
		588
		589	=item high throughput, I/O bound jobs - set load >= 2, max = 1, or very high
		590
		591	When your jobs are I/O bound, using more workers usually boils down to
		592	higher throughput, depending very much on your actual workload - sometimes
		593	having only one worker is best, for example, when you read or write big
		594	files at maixmum speed, as a second worker will increase seek times.
		595
		596	=back
		597
		598	=head1 EXCEPTIONS
		599
		600	The same "policy" as with L<AnyEvent::Fork::RPC> applies - exceptins will
		601	not be caught, and exceptions in both worker and in callbacks causes
		602	undesirable or undefined behaviour.
414		603
415	=head1 SEE ALSO	604	=head1 SEE ALSO
416		605
417	L<AnyEvent::Fork>, to create the processes in the first place.	606	L<AnyEvent::Fork>, to create the processes in the first place.
418		607

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Comparing AnyEvent-Fork-Pool/Pool.pm (file contents): Revision 1.2 by root, Thu Apr 18 21:37:27 2013 UTC vs. Revision 1.12 by root, Sun Apr 28 14:26:11 2013 UTC

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Comparing AnyEvent-Fork-Pool/Pool.pm (file contents):
Revision 1.2 by root, Thu Apr 18 21:37:27 2013 UTC vs.
Revision 1.12 by root, Sun Apr 28 14:26:11 2013 UTC