… | |
… | |
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 |
… | |
… | |
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. |
66 | |
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 | }; |
|
|
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 can "ready" it and do most other things you can |
71 | do to coro, it is mainly useful to compare again $Coro::current, to |
322 | do to coro, it is mainly useful to compare again $Coro::current, to |
72 | see whether you are running in the main program or not. |
323 | see whether you are running in the main program or not. |
73 | |
324 | |
74 | $Coro::current |
325 | $Coro::current |
75 | The Coro object representing the current coro (the last coro that |
326 | The Coro object representing the current coro (the last coro that |
… | |
… | |
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 |
|
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671 | slower than "cancel" or "terminate". |
|
|
672 | |
|
|
673 | A thread is in a safe-cancellable state if it either hasn't been run |
|
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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 |
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|
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 |
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|
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 |
|
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683 | return at all). |
|
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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 |
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687 | that your coro thread can be cancelled when you want to cancel it - |
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688 | if the thread isn't cancellable, this would be a bug somewhere, so |
|
|
689 | "->safe_cancel" croaks to notify of the bug. |
|
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690 | |
|
|
691 | In the second model you sometimes want to ask nicely to cancel a |
|
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692 | thread, but if it's not a good time, well, then don't cancel. This |
|
|
693 | can be done relatively easy like this: |
|
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694 | |
|
|
695 | if (! eval { $coro->safe_cancel }) { |
|
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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 |
|
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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 can 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:$Coro::IDLE blocked itself"), but this is just best effort |
481 | and only works when you do not run your own event loop. |
836 | and only works when you do not run your own event loop. |
482 | |
837 | |
… | |
… | |
559 | my ($rpid, $rstatus) = Coro::rouse_wait; |
914 | my ($rpid, $rstatus) = Coro::rouse_wait; |
560 | $rstatus |
915 | $rstatus |
561 | } |
916 | } |
562 | |
917 | |
563 | In the case where "rouse_cb" and "rouse_wait" are not flexible enough, |
918 | In the case where "rouse_cb" and "rouse_wait" are not flexible enough, |
564 | you can roll your own, using "schedule": |
919 | you can roll your own, using "schedule" and "ready": |
565 | |
920 | |
566 | sub wait_for_child($) { |
921 | sub wait_for_child($) { |
567 | my ($pid) = @_; |
922 | my ($pid) = @_; |
568 | |
923 | |
569 | # store the current coro in $current, |
924 | # store the current coro in $current, |
… | |
… | |
572 | my ($done, $rstatus); |
927 | my ($done, $rstatus); |
573 | |
928 | |
574 | # pass a closure to ->child |
929 | # pass a closure to ->child |
575 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
930 | my $watcher = AnyEvent->child (pid => $pid, cb => sub { |
576 | $rstatus = $_[1]; # remember rstatus |
931 | $rstatus = $_[1]; # remember rstatus |
577 | $done = 1; # mark $rstatus as valud |
932 | $done = 1; # mark $rstatus as valid |
|
|
933 | $current->ready; # wake up the waiting thread |
578 | }); |
934 | }); |
579 | |
935 | |
580 | # wait until the closure has been called |
936 | # wait until the closure has been called |
581 | schedule while !$done; |
937 | schedule while !$done; |
582 | |
938 | |
… | |
… | |
596 | in the future to allow per-thread schedulers, but Coro::State does |
952 | in the future to allow per-thread schedulers, but Coro::State does |
597 | not yet allow this). I recommend disabling thread support and using |
953 | not yet allow this). I recommend disabling thread support and using |
598 | processes, as having the windows process emulation enabled under |
954 | processes, as having the windows process emulation enabled under |
599 | unix roughly halves perl performance, even when not used. |
955 | unix roughly halves perl performance, even when not used. |
600 | |
956 | |
|
|
957 | Attempts to use threads created in another emulated process will |
|
|
958 | crash ("cleanly", with a null pointer exception). |
|
|
959 | |
601 | coro switching is not signal safe |
960 | coro switching is not signal safe |
602 | You must not switch to another coro from within a signal handler |
961 | You must not switch to another coro from within a signal handler |
603 | (only relevant with %SIG - most event libraries provide safe |
962 | (only relevant with %SIG - most event libraries provide safe |
604 | signals), *unless* you are sure you are not interrupting a Coro |
963 | signals), *unless* you are sure you are not interrupting a Coro |
605 | function. |
964 | function. |
… | |
… | |
616 | ithreads (for example, that memory or files would be shared), showing |
975 | 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 |
976 | his lack of understanding of this area - if it is hard to understand for |
618 | Chip, it is probably not obvious to everybody). |
977 | Chip, it is probably not obvious to everybody). |
619 | |
978 | |
620 | What follows is an ultra-condensed version of my talk about threads in |
979 | What follows is an ultra-condensed version of my talk about threads in |
621 | scripting languages given onthe perl workshop 2009: |
980 | scripting languages given on the perl workshop 2009: |
622 | |
981 | |
623 | The so-called "ithreads" were originally implemented for two reasons: |
982 | The so-called "ithreads" were originally implemented for two reasons: |
624 | first, to (badly) emulate unix processes on native win32 perls, and |
983 | first, to (badly) emulate unix processes on native win32 perls, and |
625 | secondly, to replace the older, real thread model ("5.005-threads"). |
984 | secondly, to replace the older, real thread model ("5.005-threads"). |
626 | |
985 | |