[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 1.8 by root, Sun Apr 21 12:28:34 2013 UTC

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

Diff Legend

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

Comparing AnyEvent-Fork-Pool/Pool.pm (file contents): Revision 1.2 by root, Thu Apr 18 21:37:27 2013 UTC vs. Revision 1.8 by root, Sun Apr 21 12:28:34 2013 UTC

Diff Legend

Comparing AnyEvent-Fork-Pool/Pool.pm (file contents):
Revision 1.2 by root, Thu Apr 18 21:37:27 2013 UTC vs.
Revision 1.8 by root, Sun Apr 21 12:28:34 2013 UTC