Commit | Line | Data |
47ba8780 |
1 | package threads; |
2 | |
32419a4c |
3 | use 5.008; |
fcea4b7c |
4 | |
47ba8780 |
5 | use strict; |
6 | use warnings; |
73e09c8f |
7 | |
9d9ff5b1 |
8 | our $VERSION = '1.31'; |
fcea4b7c |
9 | my $XS_VERSION = $VERSION; |
10 | $VERSION = eval $VERSION; |
73e09c8f |
11 | |
73e09c8f |
12 | |
fcea4b7c |
13 | BEGIN { |
14 | # Verify this Perl supports threads |
15 | use Config; |
16 | if (! $Config{useithreads}) { |
17 | die("This Perl not built to support threads\n"); |
73e09c8f |
18 | } |
47ba8780 |
19 | |
fcea4b7c |
20 | # Declare that we have been loaded |
21 | $threads::threads = 1; |
22 | |
23 | # Complain if 'threads' is loaded after 'threads::shared' |
24 | if ($threads::shared::threads_shared) { |
25 | warn <<'_MSG_'; |
26 | Warning, threads::shared has already been loaded. To |
27 | enable shared variables, 'use threads' must be called |
28 | before threads::shared or any module that uses it. |
29 | _MSG_ |
30 | } |
dab065ea |
31 | } |
32 | |
fc04eb16 |
33 | |
0f1612a7 |
34 | # Load the XS code |
35 | require XSLoader; |
fcea4b7c |
36 | XSLoader::load('threads', $XS_VERSION); |
47ba8780 |
37 | |
47ba8780 |
38 | |
0f1612a7 |
39 | ### Export ### |
47ba8780 |
40 | |
0f1612a7 |
41 | sub import |
42 | { |
43 | my $class = shift; # Not used |
44 | |
45 | # Exported subroutines |
46 | my @EXPORT = qw(async); |
47 | |
48 | # Handle args |
49 | while (my $sym = shift) { |
514612b7 |
50 | if ($sym =~ /^stack/) { |
51 | threads->set_stack_size(shift); |
52 | |
53 | } elsif ($sym =~ /all/) { |
0f1612a7 |
54 | push(@EXPORT, qw(yield)); |
55 | |
56 | } else { |
57 | push(@EXPORT, $sym); |
58 | } |
59 | } |
60 | |
61 | # Export subroutine names |
62 | my $caller = caller(); |
63 | foreach my $sym (@EXPORT) { |
64 | no strict 'refs'; |
65 | *{$caller.'::'.$sym} = \&{$sym}; |
66 | } |
514612b7 |
67 | |
68 | # Set stack size via environment variable |
69 | if (exists($ENV{'PERL5_ITHREADS_STACK_SIZE'})) { |
70 | threads->set_stack_size($ENV{'PERL5_ITHREADS_STACK_SIZE'}); |
71 | } |
0f1612a7 |
72 | } |
73 | |
74 | |
75 | ### Methods, etc. ### |
47ba8780 |
76 | |
f4cc38af |
77 | # 'new' is an alias for 'create' |
78 | *new = \&create; |
68795e93 |
79 | |
fcea4b7c |
80 | # 'async' is a function alias for the 'threads->create()' method |
81 | sub async (&;@) |
82 | { |
83 | unshift(@_, 'threads'); |
84 | # Use "goto" trick to avoid pad problems from 5.8.1 (fixed in 5.8.2) |
85 | goto &create; |
86 | } |
87 | |
88 | # Thread object equality checking |
89 | use overload ( |
90 | '==' => \&equal, |
91 | '!=' => sub { ! equal(@_) }, |
92 | 'fallback' => 1 |
93 | ); |
94 | |
47ba8780 |
95 | 1; |
0f1612a7 |
96 | |
47ba8780 |
97 | __END__ |
98 | |
99 | =head1 NAME |
100 | |
0f1612a7 |
101 | threads - Perl interpreter-based threads |
102 | |
103 | =head1 VERSION |
104 | |
9d9ff5b1 |
105 | This document describes threads version 1.31 |
47ba8780 |
106 | |
107 | =head1 SYNOPSIS |
108 | |
514612b7 |
109 | use threads ('yield', 'stack_size' => 64*4096); |
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110 | |
38875929 |
111 | sub start_thread { |
0f1612a7 |
112 | my @args = @_; |
9d9ff5b1 |
113 | print('Thread started: ', join(' ', @args), "\n"); |
38875929 |
114 | } |
0f1612a7 |
115 | my $thread = threads->create('start_thread', 'argument'); |
116 | $thread->join(); |
117 | |
118 | threads->create(sub { print("I am a thread\n"); })->join(); |
47ba8780 |
119 | |
38875929 |
120 | my $thread3 = async { foreach (@files) { ... } }; |
0f1612a7 |
121 | $thread3->join(); |
122 | |
9d9ff5b1 |
123 | # Invoke thread in list context (implicit) so it can return a list |
0f1612a7 |
124 | my ($thr) = threads->create(sub { return (qw/a b c/); }); |
9d9ff5b1 |
125 | # or specify list context explicitly |
126 | my $thr = threads->create({'context' => 'list'}, |
127 | sub { return (qw/a b c/); }); |
0f1612a7 |
128 | my @results = $thr->join(); |
47ba8780 |
129 | |
38875929 |
130 | $thread->detach(); |
47ba8780 |
131 | |
38875929 |
132 | $thread = threads->self(); |
0f1612a7 |
133 | $thread = threads->object($tid); |
11c51ed3 |
134 | |
0f1612a7 |
135 | $tid = threads->tid(); |
136 | $tid = threads->self->tid(); |
137 | $tid = $thread->tid(); |
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138 | |
38875929 |
139 | threads->yield(); |
0f1612a7 |
140 | yield(); |
141 | |
142 | my @threads = threads->list(); |
fcea4b7c |
143 | my $thread_count = threads->list(); |
f9dff5f5 |
144 | |
0f1612a7 |
145 | if ($thr1 == $thr2) { |
146 | ... |
147 | } |
678a9b6c |
148 | |
514612b7 |
149 | $stack_size = threads->get_stack_size(); |
150 | $old_size = threads->set_stack_size(32*4096); |
151 | |
9d9ff5b1 |
152 | # Create a thread with a specific context and stack size |
153 | my $thr = threads->create({ 'context' => 'list', |
154 | 'stack_size' => 32*4096 }, |
155 | \&foo); |
156 | my @results = $thr->join(); |
157 | |
c0003851 |
158 | $thr->kill('SIGUSR1'); |
159 | |
47ba8780 |
160 | =head1 DESCRIPTION |
161 | |
fc04eb16 |
162 | Perl 5.6 introduced something called interpreter threads. Interpreter threads |
163 | are different from I<5005threads> (the thread model of Perl 5.005) by creating |
164 | a new Perl interpreter per thread, and not sharing any data or state between |
165 | threads by default. |
11c51ed3 |
166 | |
fc04eb16 |
167 | Prior to Perl 5.8, this has only been available to people embedding Perl, and |
168 | for emulating fork() on Windows. |
11c51ed3 |
169 | |
fc04eb16 |
170 | The I<threads> API is loosely based on the old Thread.pm API. It is very |
171 | important to note that variables are not shared between threads, all variables |
172 | are by default thread local. To use shared variables one must use |
173 | L<threads::shared>. |
11c51ed3 |
174 | |
fc04eb16 |
175 | It is also important to note that you must enable threads by doing C<use |
176 | threads> as early as possible in the script itself, and that it is not |
177 | possible to enable threading inside an C<eval "">, C<do>, C<require>, or |
178 | C<use>. In particular, if you are intending to share variables with |
179 | L<threads::shared>, you must C<use threads> before you C<use threads::shared>. |
180 | (C<threads> will emit a warning if you do it the other way around.) |
47ba8780 |
181 | |
182 | =over |
183 | |
0f1612a7 |
184 | =item $thr = threads->create(FUNCTION, ARGS) |
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185 | |
0f1612a7 |
186 | This will create a new thread that will begin execution with the specified |
187 | entry point function, and give it the I<ARGS> list as parameters. It will |
188 | return the corresponding threads object, or C<undef> if thread creation failed. |
47ba8780 |
189 | |
0f1612a7 |
190 | I<FUNCTION> may either be the name of a function, an anonymous subroutine, or |
191 | a code ref. |
47ba8780 |
192 | |
0f1612a7 |
193 | my $thr = threads->create('func_name', ...); |
194 | # or |
195 | my $thr = threads->create(sub { ... }, ...); |
196 | # or |
197 | my $thr = threads->create(\&func, ...); |
93512b4d |
198 | |
0f1612a7 |
199 | The C<-E<gt>new()> method is an alias for C<-E<gt>create()>. |
200 | |
201 | =item $thr->join() |
202 | |
203 | This will wait for the corresponding thread to complete its execution. When |
204 | the thread finishes, C<-E<gt>join()> will return the return value(s) of the |
205 | entry point function. |
206 | |
9d9ff5b1 |
207 | The context (void, scalar or list) for the return value(s) for C<-E<gt>join()> |
208 | is determined at the time of thread creation. |
0f1612a7 |
209 | |
9d9ff5b1 |
210 | # Create thread in list context (implicit) |
0f1612a7 |
211 | my ($thr1) = threads->create(sub { |
212 | my @results = qw(a b c); |
213 | return (@results); |
9d9ff5b1 |
214 | }); |
215 | # or (explicit) |
216 | my $thr1 = threads->create({'context' => 'list'}, |
217 | sub { |
218 | my @results = qw(a b c); |
219 | return (@results); |
220 | }); |
0f1612a7 |
221 | # Retrieve list results from thread |
222 | my @res1 = $thr1->join(); |
223 | |
9d9ff5b1 |
224 | # Create thread in scalar context (implicit) |
0f1612a7 |
225 | my $thr2 = threads->create(sub { |
226 | my $result = 42; |
227 | return ($result); |
9d9ff5b1 |
228 | }); |
0f1612a7 |
229 | # Retrieve scalar result from thread |
230 | my $res2 = $thr2->join(); |
231 | |
9d9ff5b1 |
232 | # Create a thread in void context (explicit) |
233 | my $thr3 = threads->create({'void' => 1}, |
234 | sub { print("Hello, world\n"); }); |
235 | # Join the thread in void context (i.e., no return value) |
236 | $thr3->join(); |
237 | |
238 | See L</"THREAD CONTEXT"> for more details. |
239 | |
0f1612a7 |
240 | If the program exits without all other threads having been either joined or |
241 | detached, then a warning will be issued. (A program exits either because one |
242 | of its threads explicitly calls L<exit()|perlfunc/"exit EXPR">, or in the case |
243 | of the main thread, reaches the end of the main program file.) |
93512b4d |
244 | |
fcea4b7c |
245 | Calling C<-E<gt>join()> or C<-E<gt>detach()> on an already joined thread will |
246 | cause an error to be thrown. |
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247 | |
fcea4b7c |
248 | =item $thr->detach() |
47ba8780 |
249 | |
fcea4b7c |
250 | Makes the thread unjoinable, and causes any eventual return value to be |
251 | discarded. |
252 | |
253 | Calling C<-E<gt>join()> or C<-E<gt>detach()> on an already detached thread |
254 | will cause an error to be thrown. |
0f1612a7 |
255 | |
256 | =item threads->detach() |
257 | |
258 | Class method that allows a thread to detach itself. |
259 | |
fcea4b7c |
260 | =item threads->self() |
47ba8780 |
261 | |
fcea4b7c |
262 | Class method that allows a thread to obtain its own I<threads> object. |
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263 | |
0f1612a7 |
264 | =item $thr->tid() |
265 | |
266 | Returns the ID of the thread. Thread IDs are unique integers with the main |
267 | thread in a program being 0, and incrementing by 1 for every thread created. |
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268 | |
0f1612a7 |
269 | =item threads->tid() |
38875929 |
270 | |
0f1612a7 |
271 | Class method that allows a thread to obtain its own ID. |
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272 | |
0f1612a7 |
273 | =item threads->object($tid) |
8c9849ff |
274 | |
0f1612a7 |
275 | This will return the I<threads> object for the I<active> thread associated |
276 | with the specified thread ID. Returns C<undef> if there is no thread |
277 | associated with the TID, if the thread is joined or detached, if no TID is |
278 | specified or if the specified TID is undef. |
8c9849ff |
279 | |
fcea4b7c |
280 | =item threads->yield() |
f9dff5f5 |
281 | |
38875929 |
282 | This is a suggestion to the OS to let this thread yield CPU time to other |
283 | threads. What actually happens is highly dependent upon the underlying |
284 | thread implementation. |
f9dff5f5 |
285 | |
fcea4b7c |
286 | You may do C<use threads qw(yield)>, and then just use C<yield()> in your |
70f2e746 |
287 | code. |
288 | |
f4cc38af |
289 | =item threads->list() |
678a9b6c |
290 | |
f4cc38af |
291 | In a list context, returns a list of all non-joined, non-detached I<threads> |
292 | objects. In a scalar context, returns a count of the same. |
678a9b6c |
293 | |
0f1612a7 |
294 | =item $thr1->equal($thr2) |
295 | |
296 | Tests if two threads objects are the same thread or not. This is overloaded |
fcea4b7c |
297 | to the more natural forms: |
0f1612a7 |
298 | |
299 | if ($thr1 == $thr2) { |
300 | print("Threads are the same\n"); |
301 | } |
fcea4b7c |
302 | # or |
303 | if ($thr1 != $thr2) { |
304 | print("Threads differ\n"); |
305 | } |
0f1612a7 |
306 | |
307 | (Thread comparison is based on thread IDs.) |
308 | |
386c44e5 |
309 | =item async BLOCK; |
310 | |
311 | C<async> creates a thread to execute the block immediately following |
fcea4b7c |
312 | it. This block is treated as an anonymous subroutine, and so must have a |
313 | semi-colon after the closing brace. Like C<threads->create()>, C<async> |
314 | returns a I<threads> object. |
386c44e5 |
315 | |
f4cc38af |
316 | =item $thr->_handle() |
317 | |
318 | This I<private> method returns the memory location of the internal thread |
fcea4b7c |
319 | structure associated with a threads object. For Win32, this is a pointer to |
320 | the C<HANDLE> value returned by C<CreateThread> (i.e., C<HANDLE *>); for other |
321 | platforms, it is a pointer to the C<pthread_t> structure used in the |
404aaa48 |
322 | C<pthread_create> call (i.e., C<pthread_t *>). |
f4cc38af |
323 | |
324 | This method is of no use for general Perl threads programming. Its intent is |
325 | to provide other (XS-based) thread modules with the capability to access, and |
326 | possibly manipulate, the underlying thread structure associated with a Perl |
327 | thread. |
328 | |
329 | =item threads->_handle() |
330 | |
331 | Class method that allows a thread to obtain its own I<handle>. |
332 | |
47ba8780 |
333 | =back |
334 | |
9d9ff5b1 |
335 | =head1 THREAD CONTEXT |
336 | |
337 | As with subroutines, the type of value returned from a thread's entry point |
338 | function may be determined by the thread's I<context>: list, scalar or void. |
339 | The thread's context is determined at thread creation. This is necessary so |
340 | that the context is available to the entry point function via |
341 | L<wantarry()|perlfunc/"wantarray">. The thread may then specify a value of |
342 | the appropriate type to be returned from C<-E<gt>join()>. |
343 | |
344 | =head2 Explicit context |
345 | |
346 | Because thread creation and thread joining may occur in different contexts, it |
347 | may be desirable to state the context explicitly to the thread's entry point |
348 | function. This may be done by calling C<-E<gt>create()> with a parameter hash |
349 | as the first argument: |
350 | |
351 | my $thr = threads->create({'context' => 'list'}, \&foo); |
352 | ... |
353 | my @results = $thr->join(); |
354 | |
355 | In the above, the threads object is returned to the parent thread in scalar |
356 | context, and the thread's entry point function C<foo> will be called in list |
357 | context such that the parent thread can receive a list from the C<-E<gt>join()> |
358 | call. Similarly, if you need the threads object, but your thread will not be |
359 | returning a value (i.e., I<void> context), you would do the following: |
360 | |
361 | my $thr = threads->create({'context' => 'void'}, \&foo); |
362 | ... |
363 | $thr->join(); |
364 | |
365 | The context type may also be used as the I<key> in the parameter hash followed |
366 | by a I<true> value: |
367 | |
368 | threads->create({'scalar' => 1}, \&foo); |
369 | ... |
370 | my ($thr) = threads->list(); |
371 | my $result = $thr->join(); |
372 | |
373 | =head2 Implicit context |
374 | |
375 | If not explicitly stated, the thread's context is implied from the context |
376 | of the C<-E<gt>create()> call: |
377 | |
378 | # Create thread in list context |
379 | my ($thr) = threads->create(...); |
380 | |
381 | # Create thread in scalar context |
382 | my $thr = threads->create(...); |
383 | |
384 | # Create thread in void context |
385 | threads->create(...); |
386 | |
514612b7 |
387 | =head1 THREAD STACK SIZE |
388 | |
389 | The default per-thread stack size for different platforms varies |
390 | significantly, and is almost always far more than is needed for most |
391 | applications. On Win32, Perl's makefile explicitly sets the default stack to |
392 | 16 MB; on most other platforms, the system default is used, which again may be |
393 | much larger than is needed. |
394 | |
395 | By tuning the stack size to more accurately reflect your application's needs, |
396 | you may significantly reduce your application's memory usage, and increase the |
397 | number of simultaneously running threads. |
398 | |
399 | N.B., on Windows, Address space allocation granularity is 64 KB, therefore, |
400 | setting the stack smaller than that on Win32 Perl will not save any more |
401 | memory. |
402 | |
403 | =over |
404 | |
405 | =item threads->get_stack_size(); |
406 | |
407 | Returns the current default per-thread stack size. The default is zero, which |
408 | means the system default stack size is currently in use. |
409 | |
410 | =item $size = $thr->get_stack_size(); |
411 | |
412 | Returns the stack size for a particular thread. A return value of zero |
413 | indicates the system default stack size was used for the thread. |
414 | |
415 | =item $old_size = threads->set_stack_size($new_size); |
416 | |
417 | Sets a new default per-thread stack size, and returns the previous setting. |
418 | |
419 | Some platforms have a minimum thread stack size. Trying to set the stack size |
420 | below this value will result in a warning, and the minimum stack size will be |
421 | used. |
422 | |
423 | Some Linux platforms have a maximum stack size. Setting too large of a stack |
424 | size will cause thread creation to fail. |
425 | |
426 | If needed, C<$new_size> will be rounded up to the next multiple of the memory |
427 | page size (usually 4096 or 8192). |
428 | |
429 | Threads created after the stack size is set will then either call |
430 | C<pthread_attr_setstacksize()> I<(for pthreads platforms)>, or supply the |
431 | stack size to C<CreateThread()> I<(for Win32 Perl)>. |
432 | |
433 | (Obviously, this call does not affect any currently extant threads.) |
434 | |
435 | =item use threads ('stack_size' => VALUE); |
436 | |
437 | This sets the default per-thread stack size at the start of the application. |
438 | |
439 | =item $ENV{'PERL5_ITHREADS_STACK_SIZE'} |
440 | |
441 | The default per-thread stack size may be set at the start of the application |
442 | through the use of the environment variable C<PERL5_ITHREADS_STACK_SIZE>: |
443 | |
444 | PERL5_ITHREADS_STACK_SIZE=1048576 |
445 | export PERL5_ITHREADS_STACK_SIZE |
446 | perl -e'use threads; print(threads->get_stack_size(), "\n")' |
447 | |
448 | This value overrides any C<stack_size> parameter given to C<use threads>. Its |
449 | primary purpose is to permit setting the per-thread stack size for legacy |
450 | threaded applications. |
451 | |
452 | =item threads->create({'stack_size' => VALUE}, FUNCTION, ARGS) |
453 | |
9d9ff5b1 |
454 | The stack size an individual threads may also be specified. This may be done |
455 | by calling C<-E<gt>create()> with a parameter hash as the first argument: |
456 | |
457 | my $thr = threads->create({'stack_size' => 32*4096}, \&foo, @args); |
514612b7 |
458 | |
459 | =item $thr2 = $thr1->create(FUNCTION, ARGS) |
460 | |
461 | This creates a new thread (C<$thr2>) that inherits the stack size from an |
462 | existing thread (C<$thr1>). This is shorthand for the following: |
463 | |
464 | my $stack_size = $thr1->get_stack_size(); |
465 | my $thr2 = threads->create({'stack_size' => $stack_size}, FUNCTION, ARGS); |
466 | |
467 | =back |
468 | |
c0003851 |
469 | =head1 THREAD SIGNALLING |
470 | |
9d9ff5b1 |
471 | When safe signals is in effect (the default behavior - see L</"Unsafe signals"> |
1152d448 |
472 | for more details), then signals may be sent and acted upon by individual |
473 | threads. |
c0003851 |
474 | |
475 | =over 4 |
476 | |
477 | =item $thr->kill('SIG...'); |
478 | |
479 | Sends the specified signal to the thread. Signal names and (positive) signal |
480 | numbers are the same as those supported by |
481 | L<kill()|perlfunc/"kill SIGNAL, LIST">. For example, 'SIGTERM', 'TERM' and |
482 | (depending on the OS) 15 are all valid arguments to C<-E<gt>kill()>. |
483 | |
484 | Returns the thread object to allow for method chaining: |
485 | |
486 | $thr->kill('SIG...')->join(); |
487 | |
488 | =back |
489 | |
490 | Signal handlers need to be set up in the threads for the signals they are |
491 | expected to act upon. Here's an example for I<cancelling> a thread: |
492 | |
493 | use threads; |
494 | |
495 | # Suppress warning message when thread is 'killed' |
496 | no warnings 'threads'; |
497 | |
498 | sub thr_func |
499 | { |
500 | # Thread 'cancellation' signal handler |
501 | $SIG{'KILL'} = sub { die("Thread killed\n"); }; |
502 | |
503 | ... |
504 | } |
505 | |
506 | # Create a thread |
507 | my $thr = threads->create('thr_func'); |
508 | |
509 | ... |
510 | |
511 | # Signal the thread to terminate, and then detach |
512 | # it so that it will get cleaned up automatically |
513 | $thr->kill('KILL')->detach(); |
514 | |
404aaa48 |
515 | Here's another simplistic example that illustrates the use of thread |
516 | signalling in conjunction with a semaphore to provide rudimentary I<suspend> |
517 | and I<resume> capabilities: |
c0003851 |
518 | |
519 | use threads; |
520 | use Thread::Semaphore; |
521 | |
522 | sub thr_func |
523 | { |
524 | my $sema = shift; |
525 | |
526 | # Thread 'suspend/resume' signal handler |
527 | $SIG{'STOP'} = sub { |
528 | $sema->down(); # Thread suspended |
529 | $sema->up(); # Thread resumes |
530 | }; |
531 | |
532 | ... |
533 | } |
534 | |
535 | # Create a semaphore and send it to a thread |
536 | my $sema = Thread::Semaphore->new(); |
537 | my $thr = threads->create('thr_func', $sema); |
538 | |
539 | # Suspend the thread |
540 | $sema->down(); |
541 | $thr->kill('STOP'); |
542 | |
543 | ... |
544 | |
545 | # Allow the thread to continue |
546 | $sema->up(); |
547 | |
404aaa48 |
548 | CAVEAT: The thread signalling capability provided by this module does not |
549 | actually send signals via the OS. It I<emulates> signals at the Perl-level |
550 | such that signal handlers are called in the appropriate thread. For example, |
551 | sending C<$thr-E<gt>kill('STOP')> does not actually suspend a thread (or the |
552 | whole process), but does cause a C<$SIG{'STOP'}> handler to be called in that |
553 | thread (as illustrated above). |
554 | |
555 | As such, signals that would normally not be appropriate to use in the |
556 | C<kill()> command (e.g., C<kill('KILL', $$)>) are okay to use with the |
557 | C<-E<gt>kill()> method (again, as illustrated above). |
558 | |
559 | Correspondingly, sending a signal to a thread does not disrupt the operation |
560 | the thread is currently working on: The signal will be acted upon after the |
c0003851 |
561 | current operation has completed. For instance, if the thread is I<stuck> on |
562 | an I/O call, sending it a signal will not cause the I/O call to be interrupted |
563 | such that the signal is acted up immediately. |
564 | |
e4f9f4fe |
565 | =head1 WARNINGS |
566 | |
567 | =over 4 |
568 | |
fcea4b7c |
569 | =item A thread exited while # other threads were still running |
e4f9f4fe |
570 | |
fc04eb16 |
571 | A thread (not necessarily the main thread) exited while there were still other |
572 | threads running. Usually, it's a good idea to first collect the return values |
573 | of the created threads by joining them, and only then exit from the main |
574 | thread. |
e4f9f4fe |
575 | |
c0003851 |
576 | =item Thread creation failed: pthread_create returned # |
577 | |
578 | See the appropriate I<man> page for C<pthread_create> to determine the actual |
579 | cause for the failure. |
580 | |
581 | =item Thread # terminated abnormally: ... |
582 | |
583 | A thread terminated in some manner other than just returning from its entry |
584 | point function. For example, the thread may have exited via C<die>. |
585 | |
514612b7 |
586 | =item Using minimum thread stack size of # |
587 | |
588 | Some platforms have a minimum thread stack size. Trying to set the stack size |
589 | below this value will result in the above warning, and the stack size will be |
590 | set to the minimum. |
591 | |
c0003851 |
592 | =item Thread creation failed: pthread_attr_setstacksize(I<SIZE>) returned 22 |
593 | |
594 | The specified I<SIZE> exceeds the system's maximum stack size. Use a smaller |
595 | value for the stack size. |
596 | |
e4f9f4fe |
597 | =back |
47ba8780 |
598 | |
c0003851 |
599 | If needed, thread warnings can be suppressed by using: |
600 | |
601 | no warnings 'threads'; |
602 | |
603 | in the appropriate scope. |
604 | |
0f1612a7 |
605 | =head1 ERRORS |
606 | |
607 | =over 4 |
608 | |
fcea4b7c |
609 | =item This Perl not built to support threads |
678a9b6c |
610 | |
0f1612a7 |
611 | The particular copy of Perl that you're trying to use was not built using the |
612 | C<useithreads> configuration option. |
678a9b6c |
613 | |
0f1612a7 |
614 | Having threads support requires all of Perl and all of the XS modules in the |
615 | Perl installation to be rebuilt; it is not just a question of adding the |
616 | L<threads> module (i.e., threaded and non-threaded Perls are binary |
617 | incompatible.) |
618 | |
514612b7 |
619 | =item Cannot change stack size of an existing thread |
620 | |
621 | The stack size of currently extant threads cannot be changed, therefore, the |
622 | following results in the above error: |
623 | |
624 | $thr->set_stack_size($size); |
625 | |
c0003851 |
626 | =item Cannot signal other threads without safe signals |
514612b7 |
627 | |
1152d448 |
628 | Safe signals must be in effect to use the C<-E<gt>kill()> signalling method. |
9d9ff5b1 |
629 | See L</"Unsafe signals"> for more details. |
c0003851 |
630 | |
631 | =item Unrecognized signal name: ... |
632 | |
633 | The particular copy of Perl that you're trying to use does not support the |
634 | specified signal being used in a C<-E<gt>kill()> call. |
514612b7 |
635 | |
0f1612a7 |
636 | =back |
47ba8780 |
637 | |
ab80e3f2 |
638 | =head1 BUGS |
639 | |
47ba8780 |
640 | =over |
641 | |
fcea4b7c |
642 | =item Parent-child threads |
678a9b6c |
643 | |
fcea4b7c |
644 | On some platforms, it might not be possible to destroy I<parent> threads while |
645 | there are still existing I<child> threads. |
678a9b6c |
646 | |
404aaa48 |
647 | =item Creating threads inside special blocks |
88f8c1df |
648 | |
f2e0bb91 |
649 | Creating threads inside C<BEGIN>, C<CHECK> or C<INIT> blocks should not be |
650 | relied upon. Depending on the Perl version and the application code, results |
651 | may range from success, to (apparently harmless) warnings of leaked scalar, |
652 | all the way up to crashing of the Perl interpreter. |
88f8c1df |
653 | |
1152d448 |
654 | =item Unsafe signals |
47ba8780 |
655 | |
1152d448 |
656 | Since Perl 5.8.0, signals have been made safer in Perl by postponing their |
657 | handling until the interpreter is in a I<safe> state. See |
404aaa48 |
658 | L<perl58delta/"Safe Signals"> and L<perlipc/"Deferred Signals (Safe Signals)"> |
1152d448 |
659 | for more details. |
660 | |
661 | Safe signals is the default behavior, and the old, immediate, unsafe |
662 | signalling behavior is only in effect in the following situations: |
663 | |
664 | =over 4 |
665 | |
666 | =item * Perl was been built with C<PERL_OLD_SIGNALS> (see C<perl -V>). |
667 | |
668 | =item * The environment variable C<PERL_SIGNALS> is set to C<unsafe> (see L<perlrun/"PERL_SIGNALS">). |
669 | |
670 | =item * The module L<Perl::Unsafe::Signals> is used. |
671 | |
672 | =back |
673 | |
674 | If unsafe signals is in effect, then signal handling is not thread-safe, and |
675 | the C<-E<gt>kill()> signalling method cannot be used. |
88f8c1df |
676 | |
0f1612a7 |
677 | =item Returning closures from threads |
678 | |
f2e0bb91 |
679 | Returning closures from threads should not be relied upon. Depending of the |
680 | Perl version and the application code, results may range from success, to |
404aaa48 |
681 | (apparently harmless) warnings of leaked scalar, all the way up to crashing of |
682 | the Perl interpreter. |
0f1612a7 |
683 | |
684 | =item Perl Bugs and the CPAN Version of L<threads> |
685 | |
686 | Support for threads extents beyond the code in this module (i.e., |
687 | F<threads.pm> and F<threads.xs>), and into the Perl iterpreter itself. Older |
688 | versions of Perl contain bugs that may manifest themselves despite using the |
689 | latest version of L<threads> from CPAN. There is no workaround for this other |
690 | than upgrading to the lastest version of Perl. |
691 | |
692 | (Before you consider posting a bug report, please consult, and possibly post a |
693 | message to the discussion forum to see if what you've encountered is a known |
694 | problem.) |
695 | |
47ba8780 |
696 | =back |
697 | |
0f1612a7 |
698 | =head1 REQUIREMENTS |
47ba8780 |
699 | |
0f1612a7 |
700 | Perl 5.8.0 or later |
47ba8780 |
701 | |
0f1612a7 |
702 | =head1 SEE ALSO |
47ba8780 |
703 | |
0f1612a7 |
704 | L<threads> Discussion Forum on CPAN: |
705 | L<http://www.cpanforum.com/dist/threads> |
47ba8780 |
706 | |
0f1612a7 |
707 | Annotated POD for L<threads>: |
9d9ff5b1 |
708 | L<http://annocpan.org/~JDHEDDEN/threads-1.31/shared.pm> |
47ba8780 |
709 | |
0f1612a7 |
710 | L<threads::shared>, L<perlthrtut> |
47ba8780 |
711 | |
0f1612a7 |
712 | L<http://www.perl.com/pub/a/2002/06/11/threads.html> and |
713 | L<http://www.perl.com/pub/a/2002/09/04/threads.html> |
47ba8780 |
714 | |
0f1612a7 |
715 | Perl threads mailing list: |
716 | L<http://lists.cpan.org/showlist.cgi?name=iThreads> |
47ba8780 |
717 | |
514612b7 |
718 | Stack size discussion: |
719 | L<http://www.perlmonks.org/?node_id=532956> |
720 | |
0f1612a7 |
721 | =head1 AUTHOR |
47ba8780 |
722 | |
0f1612a7 |
723 | Artur Bergman E<lt>sky AT crucially DOT netE<gt> |
724 | |
725 | threads is released under the same license as Perl. |
726 | |
727 | CPAN version produced by Jerry D. Hedden <jdhedden AT cpan DOT org> |
728 | |
729 | =head1 ACKNOWLEDGEMENTS |
730 | |
731 | Richard Soderberg E<lt>perl AT crystalflame DOT netE<gt> - |
732 | Helping me out tons, trying to find reasons for races and other weird bugs! |
733 | |
734 | Simon Cozens E<lt>simon AT brecon DOT co DOT ukE<gt> - |
735 | Being there to answer zillions of annoying questions |
736 | |
737 | Rocco Caputo E<lt>troc AT netrus DOT netE<gt> |
47ba8780 |
738 | |
0f1612a7 |
739 | Vipul Ved Prakash E<lt>mail AT vipul DOT netE<gt> - |
740 | Helping with debugging |
47ba8780 |
741 | |
514612b7 |
742 | Dean Arnold E<lt>darnold AT presicient DOT comE<gt> - |
743 | Stack size API |
744 | |
47ba8780 |
745 | =cut |