[ViewVC] Diff of: cvs/Coro/README

Comparing Coro/README (file contents):
Revision 1.27 by root, Fri Dec 25 07:17:12 2009 UTC vs.
Revision 1.30 by root, Wed Jun 29 17:58:52 2011 UTC

…		…
14	cede; # yield to coro	14	cede; # yield to coro
15	print "3\n";	15	print "3\n";
16	cede; # and again	16	cede; # and again
17		17
18	# use locking	18	# use locking
19	use Coro::Semaphore;
20	my $lock = new Coro::Semaphore;	19	my $lock = new Coro::Semaphore;
21	my $locked;	20	my $locked;
22		21
23	$lock->down;	22	$lock->down;
24	$locked = 1;	23	$locked = 1;
…		…
38	are rarely an issue, making thread programming much safer and easier	37	are rarely an issue, making thread programming much safer and easier
39	than using other thread models.	38	than using other thread models.
40		39
41	Unlike the so-called "Perl threads" (which are not actually real threads	40	Unlike the so-called "Perl threads" (which are not actually real threads
42	but only the windows process emulation (see section of same name for	41	but only the windows process emulation (see section of same name for
43	more details) ported to unix, and as such act as processes), Coro	42	more details) ported to UNIX, and as such act as processes), Coro
44	provides a full shared address space, which makes communication between	43	provides a full shared address space, which makes communication between
45	threads very easy. And Coro's threads are fast, too: disabling the	44	threads very easy. And coro threads are fast, too: disabling the Windows
46	Windows process emulation code in your perl and using Coro can easily	45	process emulation code in your perl and using Coro can easily result in
47	result in a two to four times speed increase for your programs. A	46	a two to four times speed increase for your programs. A parallel matrix
48	parallel matrix multiplication benchmark runs over 300 times faster on a	47	multiplication benchmark (very communication-intensive) runs over 300
49	single core than perl's pseudo-threads on a quad core using all four	48	times faster on a single core than perls pseudo-threads on a quad core
50	cores.	49	using all four cores.
51		50
52	Coro achieves that by supporting multiple running interpreters that	51	Coro achieves that by supporting multiple running interpreters that
53	share data, which is especially useful to code pseudo-parallel processes	52	share data, which is especially useful to code pseudo-parallel processes
54	and for event-based programming, such as multiple HTTP-GET requests	53	and for event-based programming, such as multiple HTTP-GET requests
55	running concurrently. See Coro::AnyEvent to learn more on how to	54	running concurrently. See Coro::AnyEvent to learn more on how to
…		…
61	important global variables (see Coro::State for more configuration and	60	important global variables (see Coro::State for more configuration and
62	background info).	61	background info).
63		62
64	See also the "SEE ALSO" section at the end of this document - the Coro	63	See also the "SEE ALSO" section at the end of this document - the Coro
65	module family is quite large.	64	module family is quite large.
		65
		66	CORO THREAD LIFE CYCLE
		67	During the long and exciting (or not) life of a coro thread, it goes
		68	through a number of states:
		69
		70	1. Creation
		71	The first thing in the life of a coro thread is it's creation -
		72	obviously. The typical way to create a thread is to call the "async
		73	BLOCK" function:
		74
		75	async {
		76	# thread code goes here
		77	};
		78
		79	You can also pass arguments, which are put in @_:
		80
		81	async {
		82	print $_[1]; # prints 2
		83	} 1, 2, 3;
		84
		85	This creates a new coro thread and puts it into the ready queue,
		86	meaning it will run as soon as the CPU is free for it.
		87
		88	"async" will return a Coro object - you can store this for future
		89	reference or ignore it - a thread that is running, ready to run or
		90	waiting for some event is alive on it's own.
		91
		92	Another way to create a thread is to call the "new" constructor with
		93	a code-reference:
		94
		95	new Coro sub {
		96	# thread code goes here
		97	}, @optional_arguments;
		98
		99	This is quite similar to calling "async", but the important
		100	difference is that the new thread is not put into the ready queue,
		101	so the thread will not run until somebody puts it there. "async" is,
		102	therefore, identical to this sequence:
		103
		104	my $coro = new Coro sub {
		105	# thread code goes here
		106	};
		107	$coro->ready;
		108	return $coro;
		109
		110	2. Startup
		111	When a new coro thread is created, only a copy of the code reference
		112	and the arguments are stored, no extra memory for stacks and so on
		113	is allocated, keeping the coro thread in a low-memory state.
		114
		115	Only when it actually starts executing will all the resources be
		116	finally allocated.
		117
		118	The optional arguments specified at coro creation are available in
		119	@_, similar to function calls.
		120
		121	3. Running / Blocking
		122	A lot can happen after the coro thread has started running. Quite
		123	usually, it will not run to the end in one go (because you could use
		124	a function instead), but it will give up the CPU regularly because
		125	it waits for external events.
		126
		127	As long as a coro thread runs, its Coro object is available in the
		128	global variable $Coro::current.
		129
		130	The low-level way to give up the CPU is to call the scheduler, which
		131	selects a new coro thread to run:
		132
		133	Coro::schedule;
		134
		135	Since running threads are not in the ready queue, calling the
		136	scheduler without doing anything else will block the coro thread
		137	forever - you need to arrange either for the coro to put woken up
		138	(readied) by some other event or some other thread, or you can put
		139	it into the ready queue before scheduling:
		140
		141	# this is exactly what Coro::cede does
		142	$Coro::current->ready;
		143	Coro::schedule;
		144
		145	All the higher-level synchronisation methods (Coro::Semaphore,
		146	Coro::rouse_*...) are actually implemented via "->ready" and
		147	"Coro::schedule".
		148
		149	While the coro thread is running it also might get assigned a
		150	C-level thread, or the C-level thread might be unassigned from it,
		151	as the Coro runtime wishes. A C-level thread needs to be assigned
		152	when your perl thread calls into some C-level function and that
		153	function in turn calls perl and perl then wants to switch
		154	coroutines. This happens most often when you run an event loop and
		155	block in the callback, or when perl itself calls some function such
		156	as "AUTOLOAD" or methods via the "tie" mechanism.
		157
		158	4. Termination
		159	Many threads actually terminate after some time. There are a number
		160	of ways to terminate a coro thread, the simplest is returning from
		161	the top-level code reference:
		162
		163	async {
		164	# after returning from here, the coro thread is terminated
		165	};
		166
		167	async {
		168	return if 0.5 < rand; # terminate a little earlier, maybe
		169	print "got a chance to print this\n";
		170	# or here
		171	};
		172
		173	Any values returned from the coroutine can be recovered using
		174	"->join":
		175
		176	my $coro = async {
		177	"hello, world\n" # return a string
		178	};
		179
		180	my $hello_world = $coro->join;
		181
		182	print $hello_world;
		183
		184	Another way to terminate is to call "Coro::terminate", which at any
		185	subroutine call nesting level:
		186
		187	async {
		188	Coro::terminate "return value 1", "return value 2";
		189	};
		190
		191	And yet another way is to "->cancel" (or "->safe_cancel") the coro
		192	thread from another thread:
		193
		194	my $coro = async {
		195	exit 1;
		196	};
		197
		198	$coro->cancel; # also accepts values for ->join to retrieve
		199
		200	Cancellation can be dangerous - it's a bit like calling "exit"
		201	without actually exiting, and might leave C libraries and XS modules
		202	in a weird state. Unlike other thread implementations, however, Coro
		203	is exceptionally safe with regards to cancellation, as perl will
		204	always be in a consistent state, and for those cases where you want
		205	to do truly marvellous things with your coro while it is being
		206	cancelled - that is, make sure all cleanup code is executed from the
		207	thread being cancelled - there is even a "->safe_cancel" method.
		208
		209	So, cancelling a thread that runs in an XS event loop might not be
		210	the best idea, but any other combination that deals with perl only
		211	(cancelling when a thread is in a "tie" method or an "AUTOLOAD" for
		212	example) is safe.
		213
		214	Lastly, a coro thread object that isn't referenced is "->cancel"'ed
		215	automatically - just like other objects in Perl. This is not such a
		216	common case, however - a running thread is referencedy b
		217	$Coro::current, a thread ready to run is referenced by the ready
		218	queue, a thread waiting on a lock or semaphore is referenced by
		219	being in some wait list and so on. But a thread that isn't in any of
		220	those queues gets cancelled:
		221
		222	async {
		223	schedule; # cede to other coros, don't go into the ready queue
		224	};
		225
		226	cede;
		227	# now the async above is destroyed, as it is not referenced by anything.
		228
		229	5. Cleanup
		230	Threads will allocate various resources. Most but not all will be
		231	returned when a thread terminates, during clean-up.
		232
		233	Cleanup is quite similar to throwing an uncaught exception: perl
		234	will work it's way up through all subroutine calls and blocks. On
		235	it's way, it will release all "my" variables, undo all "local"'s and
		236	free any other resources truly local to the thread.
		237
		238	So, a common way to free resources is to keep them referenced only
		239	by my variables:
		240
		241	async {
		242	my $big_cache = new Cache ...;
		243	};
		244
		245	If there are no other references, then the $big_cache object will be
		246	freed when the thread terminates, regardless of how it does so.
		247
		248	What it does "NOT" do is unlock any Coro::Semaphores or similar
		249	resources, but that's where the "guard" methods come in handy:
		250
		251	my $sem = new Coro::Semaphore;
		252
		253	async {
		254	my $lock_guard = $sem->guard;
		255	# if we reutrn, or die or get cancelled, here,
		256	# then the semaphore will be "up"ed.
		257	};
		258
		259	The "Guard::guard" function comes in handy for any custom cleanup
		260	you might want to do (but you cannot switch to other coroutines form
		261	those code blocks):
		262
		263	async {
		264	my $window = new Gtk2::Window "toplevel";
		265	# The window will not be cleaned up automatically, even when $window
		266	# gets freed, so use a guard to ensure it's destruction
		267	# in case of an error:
		268	my $window_guard = Guard::guard { $window->destroy };
		269
		270	# we are safe here
		271	};
		272
		273	Last not least, "local" can often be handy, too, e.g. when
		274	temporarily replacing the coro thread description:
		275
		276	sub myfunction {
		277	local $Coro::current->{desc} = "inside myfunction(@_)";
		278
		279	# if we return or die here, the description will be restored
		280	}
		281
		282	6. Viva La Zombie Muerte
		283	Even after a thread has terminated and cleaned up its resources, the
		284	Coro object still is there and stores the return values of the
		285	thread.
		286
		287	The means the Coro object gets freed automatically when the thread
		288	has terminated and cleaned up and there arenot other references.
		289
		290	If there are, the Coro object will stay around, and you can call
		291	"->join" as many times as you wish to retrieve the result values:
		292
		293	async {
		294	print "hi\n";
		295	1
		296	};
		297
		298	# run the async above, and free everything before returning
		299	# from Coro::cede:
		300	Coro::cede;
		301
		302	{
		303	my $coro = async {
		304	print "hi\n";
		305	1
		306	};
		307
		308	# run the async above, and clean up, but do not free the coro
		309	# object:
		310	Coro::cede;
		311
		312	# optionally retrieve the result values
		313	my @results = $coro->join;
		314
		315	# now $coro goes out of scope, and presumably gets freed
		316	};
66		317
67	GLOBAL VARIABLES	318	GLOBAL VARIABLES
68	$Coro::main	319	$Coro::main
69	This variable stores the Coro object that represents the main	320	This variable stores the Coro object that represents the main
70	program. While you cna "ready" it and do most other things you can	321	program. While you cna "ready" it and do most other things you can
…		…
92	The default implementation dies with "FATAL: deadlock detected.",	343	The default implementation dies with "FATAL: deadlock detected.",
93	followed by a thread listing, because the program has no other way	344	followed by a thread listing, because the program has no other way
94	to continue.	345	to continue.
95		346
96	This hook is overwritten by modules such as "Coro::EV" and	347	This hook is overwritten by modules such as "Coro::EV" and
97	"Coro::AnyEvent" to wait on an external event that hopefully wake up	348	"Coro::AnyEvent" to wait on an external event that hopefully wakes
98	a coro so the scheduler can run it.	349	up a coro so the scheduler can run it.
99		350
100	See Coro::EV or Coro::AnyEvent for examples of using this technique.	351	See Coro::EV or Coro::AnyEvent for examples of using this technique.
101		352
102	SIMPLE CORO CREATION	353	SIMPLE CORO CREATION
103	async { ... } [@args...]	354	async { ... } [@args...]
…		…
203	any coro, regardless of priority. This is useful sometimes to	454	any coro, regardless of priority. This is useful sometimes to
204	ensure progress is made.	455	ensure progress is made.
205		456
206	terminate [arg...]	457	terminate [arg...]
207	Terminates the current coro with the given status values (see	458	Terminates the current coro with the given status values (see
208	cancel).	459	cancel). The values will not be copied, but referenced directly.
209		460
210	Coro::on_enter BLOCK, Coro::on_leave BLOCK	461	Coro::on_enter BLOCK, Coro::on_leave BLOCK
211	These function install enter and leave winders in the current scope.	462	These function install enter and leave winders in the current scope.
212	The enter block will be executed when on_enter is called and	463	The enter block will be executed when on_enter is called and
213	whenever the current coro is re-entered by the scheduler, while the	464	whenever the current coro is re-entered by the scheduler, while the
…		…
345	To avoid this, it is best to put a suspended coro into the ready	596	To avoid this, it is best to put a suspended coro into the ready
346	queue unconditionally, as every synchronisation mechanism must	597	queue unconditionally, as every synchronisation mechanism must
347	protect itself against spurious wakeups, and the one in the Coro	598	protect itself against spurious wakeups, and the one in the Coro
348	family certainly do that.	599	family certainly do that.
349		600
		601	$state->is_new
		602	Returns true iff this Coro object is "new", i.e. has never been run
		603	yet. Those states basically consist of only the code reference to
		604	call and the arguments, but consumes very little other resources.
		605	New states will automatically get assigned a perl interpreter when
		606	they are transfered to.
		607
		608	$state->is_zombie
		609	Returns true iff the Coro object has been cancelled, i.e. it's
		610	resources freed because they were "cancel"'ed, "terminate"'d,
		611	"safe_cancel"'ed or simply went out of scope.
		612
		613	The name "zombie" stems from UNIX culture, where a process that has
		614	exited and only stores and exit status and no other resources is
		615	called a "zombie".
		616
350	$is_ready = $coro->is_ready	617	$is_ready = $coro->is_ready
351	Returns true iff the Coro object is in the ready queue. Unless the	618	Returns true iff the Coro object is in the ready queue. Unless the
352	Coro object gets destroyed, it will eventually be scheduled by the	619	Coro object gets destroyed, it will eventually be scheduled by the
353	scheduler.	620	scheduler.
354		621
…		…
360	$is_suspended = $coro->is_suspended	627	$is_suspended = $coro->is_suspended
361	Returns true iff this Coro object has been suspended. Suspended	628	Returns true iff this Coro object has been suspended. Suspended
362	Coros will not ever be scheduled.	629	Coros will not ever be scheduled.
363		630
364	$coro->cancel (arg...)	631	$coro->cancel (arg...)
365	Terminates the given Coro and makes it return the given arguments as	632	Terminates the given Coro thread and makes it return the given
366	status (default: the empty list). Never returns if the Coro is the	633	arguments as status (default: an empty list). Never returns if the
367	current Coro.	634	Coro is the current Coro.
		635
		636	This is a rather brutal way to free a coro, with some limitations -
		637	if the thread is inside a C callback that doesn't expect to be
		638	canceled, bad things can happen, or if the cancelled thread insists
		639	on running complicated cleanup handlers that rely on its thread
		640	context, things will not work.
		641
		642	Any cleanup code being run (e.g. from "guard" blocks) will be run
		643	without a thread context, and is not allowed to switch to other
		644	threads. On the plus side, "->cancel" will always clean up the
		645	thread, no matter what. If your cleanup code is complex or you want
		646	to avoid cancelling a C-thread that doesn't know how to clean up
		647	itself, it can be better to "->throw" an exception, or use
		648	"->safe_cancel".
		649
		650	The arguments to "->cancel" are not copied, but instead will be
		651	referenced directly (e.g. if you pass $var and after the call change
		652	that variable, then you might change the return values passed to
		653	e.g. "join", so don't do that).
		654
		655	The resources of the Coro are usually freed (or destructed) before
		656	this call returns, but this can be delayed for an indefinite amount
		657	of time, as in some cases the manager thread has to run first to
		658	actually destruct the Coro object.
		659
		660	$coro->safe_cancel ($arg...)
		661	Works mostly like "->cancel", but is inherently "safer", and
		662	consequently, can fail with an exception in cases the thread is not
		663	in a cancellable state.
		664
		665	This method works a bit like throwing an exception that cannot be
		666	caught - specifically, it will clean up the thread from within
		667	itself, so all cleanup handlers (e.g. "guard" blocks) are run with
		668	full thread context and can block if they wish. The downside is that
		669	there is no guarantee that the thread can be cancelled when you call
		670	this method, and therefore, it might fail. It is also considerably
		671	slower than "cancel" or "terminate".
		672
		673	A thread is in a safe-cancellable state if it either hasn't been run
		674	yet, or it has no C context attached and is inside an SLF function.
		675
		676	The latter two basically mean that the thread isn't currently inside
		677	a perl callback called from some C function (usually via some XS
		678	modules) and isn't currently executing inside some C function itself
		679	(via Coro's XS API).
		680
		681	This call returns true when it could cancel the thread, or croaks
		682	with an error otherwise (i.e. it either returns true or doesn't
		683	return at all).
		684
		685	Why the weird interface? Well, there are two common models on how
		686	and when to cancel things. In the first, you have the expectation
		687	that your coro thread can be cancelled when you want to cancel it -
		688	if the thread isn't cancellable, this would be a bug somewhere, so
		689	"->safe_cancel" croaks to notify of the bug.
		690
		691	In the second model you sometimes want to ask nicely to cancel a
		692	thread, but if it's not a good time, well, then don't cancel. This
		693	can be done relatively easy like this:
		694
		695	if (! eval { $coro->safe_cancel }) {
		696	warn "unable to cancel thread: $@";
		697	}
		698
		699	However, what you never should do is first try to cancel "safely"
		700	and if that fails, cancel the "hard" way with "->cancel". That makes
		701	no sense: either you rely on being able to execute cleanup code in
		702	your thread context, or you don't. If you do, then "->safe_cancel"
		703	is the only way, and if you don't, then "->cancel" is always faster
		704	and more direct.
368		705
369	$coro->schedule_to	706	$coro->schedule_to
370	Puts the current coro to sleep (like "Coro::schedule"), but instead	707	Puts the current coro to sleep (like "Coro::schedule"), but instead
371	of continuing with the next coro from the ready queue, always switch	708	of continuing with the next coro from the ready queue, always switch
372	to the given coro object (regardless of priority etc.). The	709	to the given coro object (regardless of priority etc.). The
…		…
389	Otherwise clears the exception object.	726	Otherwise clears the exception object.
390		727
391	Coro will check for the exception each time a schedule-like-function	728	Coro will check for the exception each time a schedule-like-function
392	returns, i.e. after each "schedule", "cede",	729	returns, i.e. after each "schedule", "cede",
393	"Coro::Semaphore->down", "Coro::Handle->readable" and so on. Most of	730	"Coro::Semaphore->down", "Coro::Handle->readable" and so on. Most of
394	these functions detect this case and return early in case an	731	those functions (all that are part of Coro itself) detect this case
395	exception is pending.	732	and return early in case an exception is pending.
396		733
397	The exception object will be thrown "as is" with the specified	734	The exception object will be thrown "as is" with the specified
398	scalar in $@, i.e. if it is a string, no line number or newline will	735	scalar in $@, i.e. if it is a string, no line number or newline will
399	be appended (unlike with "die").	736	be appended (unlike with "die").
400		737
401	This can be used as a softer means than "cancel" to ask a coro to	738	This can be used as a softer means than either "cancel" or
402	end itself, although there is no guarantee that the exception will	739	"safe_cancel "to ask a coro to end itself, although there is no
403	lead to termination, and if the exception isn't caught it might well	740	guarantee that the exception will lead to termination, and if the
404	end the whole program.	741	exception isn't caught it might well end the whole program.
405		742
406	You might also think of "throw" as being the moral equivalent of	743	You might also think of "throw" as being the moral equivalent of
407	"kill"ing a coro with a signal (in this case, a scalar).	744	"kill"ing a coro with a signal (in this case, a scalar).
408		745
409	$coro->join	746	$coro->join
410	Wait until the coro terminates and return any values given to the	747	Wait until the coro terminates and return any values given to the
411	"terminate" or "cancel" functions. "join" can be called concurrently	748	"terminate" or "cancel" functions. "join" can be called concurrently
412	from multiple coro, and all will be resumed and given the status	749	from multiple threads, and all will be resumed and given the status
413	return once the $coro terminates.	750	return once the $coro terminates.
414		751
415	$coro->on_destroy (\&cb)	752	$coro->on_destroy (\&cb)
416	Registers a callback that is called when this coro gets destroyed,	753	Registers a callback that is called when this coro thread gets
		754	destroyed, that is, after it's resources have been freed but before
417	but before it is joined. The callback gets passed the terminate	755	it is joined. The callback gets passed the terminate/cancel
418	arguments, if any, and must not die, under any circumstances.	756	arguments, if any, and must not die, under any circumstances.
419		757
		758	There can be any number of "on_destroy" callbacks per coro, and
		759	there is no way currently to remove a callback once added.
		760
420	$oldprio = $coro->prio ($newprio)	761	$oldprio = $coro->prio ($newprio)
421	Sets (or gets, if the argument is missing) the priority of the coro.	762	Sets (or gets, if the argument is missing) the priority of the coro
422	Higher priority coro get run before lower priority coro. Priorities	763	thread. Higher priority coro get run before lower priority coros.
423	are small signed integers (currently -4 .. +3), that you can refer	764	Priorities are small signed integers (currently -4 .. +3), that you
424	to using PRIO_xxx constants (use the import tag :prio to get then):	765	can refer to using PRIO_xxx constants (use the import tag :prio to
		766	get then):
425		767
426	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	768	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
427	3 > 1 > 0 > -1 > -3 > -4	769	3 > 1 > 0 > -1 > -3 > -4
428		770
429	# set priority to HIGH	771	# set priority to HIGH
430	current->prio (PRIO_HIGH);	772	current->prio (PRIO_HIGH);
431		773
432	The idle coro ($Coro::idle) always has a lower priority than any	774	The idle coro thread ($Coro::idle) always has a lower priority than
433	existing coro.	775	any existing coro.
434		776
435	Changing the priority of the current coro will take effect	777	Changing the priority of the current coro will take effect
436	immediately, but changing the priority of coro in the ready queue	778	immediately, but changing the priority of a coro in the ready queue
437	(but not running) will only take effect after the next schedule (of	779	(but not running) will only take effect after the next schedule (of
438	that coro). This is a bug that will be fixed in some future version.	780	that coro). This is a bug that will be fixed in some future version.
439		781
440	$newprio = $coro->nice ($change)	782	$newprio = $coro->nice ($change)
441	Similar to "prio", but subtract the given value from the priority	783	Similar to "prio", but subtract the given value from the priority
442	(i.e. higher values mean lower priority, just as in unix).	784	(i.e. higher values mean lower priority, just as in UNIX's nice
		785	command).
443		786
444	$olddesc = $coro->desc ($newdesc)	787	$olddesc = $coro->desc ($newdesc)
445	Sets (or gets in case the argument is missing) the description for	788	Sets (or gets in case the argument is missing) the description for
446	this coro. This is just a free-form string you can associate with a	789	this coro thread. This is just a free-form string you can associate
447	coro.	790	with a coro.
448		791
449	This method simply sets the "$coro->{desc}" member to the given	792	This method simply sets the "$coro->{desc}" member to the given
450	string. You can modify this member directly if you wish.	793	string. You can modify this member directly if you wish, and in
		794	fact, this is often preferred to indicate major processing states
		795	that cna then be seen for example in a Coro::Debug session:
		796
		797	sub my_long_function {
		798	local $Coro::current->{desc} = "now in my_long_function";
		799	...
		800	$Coro::current->{desc} = "my_long_function: phase 1";
		801	...
		802	$Coro::current->{desc} = "my_long_function: phase 2";
		803	...
		804	}
451		805
452	GLOBAL FUNCTIONS	806	GLOBAL FUNCTIONS
453	Coro::nready	807	Coro::nready
454	Returns the number of coro that are currently in the ready state,	808	Returns the number of coro that are currently in the ready state,
455	i.e. that can be switched to by calling "schedule" directory or	809	i.e. that can be switched to by calling "schedule" directory or
…		…
472	The reason this function exists is that many event libraries (such	826	The reason this function exists is that many event libraries (such
473	as the venerable Event module) are not thread-safe (a weaker form of	827	as the venerable Event module) are not thread-safe (a weaker form of
474	reentrancy). This means you must not block within event callbacks,	828	reentrancy). This means you must not block within event callbacks,
475	otherwise you might suffer from crashes or worse. The only event	829	otherwise you might suffer from crashes or worse. The only event
476	library currently known that is safe to use without "unblock_sub" is	830	library currently known that is safe to use without "unblock_sub" is
477	EV.	831	EV (but you might still run into deadlocks if all event loops are
		832	blocked).
478		833
479	Coro will try to catch you when you block in the event loop	834	Coro will try to catch you when you block in the event loop
480	("FATAL:$Coro::IDLE blocked itself"), but this is just best effort	835	("FATAL:$Coro::IDLE blocked itself"), but this is just best effort
481	and only works when you do not run your own event loop.	836	and only works when you do not run your own event loop.
482		837
…		…
596	in the future to allow per-thread schedulers, but Coro::State does	951	in the future to allow per-thread schedulers, but Coro::State does
597	not yet allow this). I recommend disabling thread support and using	952	not yet allow this). I recommend disabling thread support and using
598	processes, as having the windows process emulation enabled under	953	processes, as having the windows process emulation enabled under
599	unix roughly halves perl performance, even when not used.	954	unix roughly halves perl performance, even when not used.
600		955
		956	Attempts to use threads created in another emulated process will
		957	crash ("cleanly", with a null pointer exception).
		958
601	coro switching is not signal safe	959	coro switching is not signal safe
602	You must not switch to another coro from within a signal handler	960	You must not switch to another coro from within a signal handler
603	(only relevant with %SIG - most event libraries provide safe	961	(only relevant with %SIG - most event libraries provide safe
604	signals), unless you are sure you are not interrupting a Coro	962	signals), unless you are sure you are not interrupting a Coro
605	function.	963	function.
…		…
616	ithreads (for example, that memory or files would be shared), showing	974	ithreads (for example, that memory or files would be shared), showing
617	his lack of understanding of this area - if it is hard to understand for	975	his lack of understanding of this area - if it is hard to understand for
618	Chip, it is probably not obvious to everybody).	976	Chip, it is probably not obvious to everybody).
619		977
620	What follows is an ultra-condensed version of my talk about threads in	978	What follows is an ultra-condensed version of my talk about threads in
621	scripting languages given onthe perl workshop 2009:	979	scripting languages given on the perl workshop 2009:
622		980
623	The so-called "ithreads" were originally implemented for two reasons:	981	The so-called "ithreads" were originally implemented for two reasons:
624	first, to (badly) emulate unix processes on native win32 perls, and	982	first, to (badly) emulate unix processes on native win32 perls, and
625	secondly, to replace the older, real thread model ("5.005-threads").	983	secondly, to replace the older, real thread model ("5.005-threads").
626		984

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Revision 1.27 by root, Fri Dec 25 07:17:12 2009 UTC vs.
Revision 1.30 by root, Wed Jun 29 17:58:52 2011 UTC