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1 | package threads; |
2 | |
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3 | use 5.008; |
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4 | |
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5 | use strict; |
6 | use warnings; |
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7 | |
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8 | our $VERSION = '1.24_01'; |
9 | my $XS_VERSION = $VERSION; |
10 | $VERSION = eval $VERSION; |
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11 | |
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12 | |
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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"); |
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18 | } |
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19 | |
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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 | } |
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31 | } |
32 | |
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33 | # Load the XS code |
34 | require XSLoader; |
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35 | XSLoader::load('threads', $XS_VERSION); |
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36 | |
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37 | |
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38 | ### Export ### |
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39 | |
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40 | sub import |
41 | { |
42 | my $class = shift; # Not used |
43 | |
44 | # Exported subroutines |
45 | my @EXPORT = qw(async); |
46 | |
47 | # Handle args |
48 | while (my $sym = shift) { |
49 | if ($sym =~ /all/) { |
50 | push(@EXPORT, qw(yield)); |
51 | |
52 | } else { |
53 | push(@EXPORT, $sym); |
54 | } |
55 | } |
56 | |
57 | # Export subroutine names |
58 | my $caller = caller(); |
59 | foreach my $sym (@EXPORT) { |
60 | no strict 'refs'; |
61 | *{$caller.'::'.$sym} = \&{$sym}; |
62 | } |
63 | } |
64 | |
65 | |
66 | ### Methods, etc. ### |
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67 | |
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68 | # 'new' is an alias for 'create' |
69 | *new = \&create; |
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70 | |
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71 | # 'async' is a function alias for the 'threads->create()' method |
72 | sub async (&;@) |
73 | { |
74 | unshift(@_, 'threads'); |
75 | # Use "goto" trick to avoid pad problems from 5.8.1 (fixed in 5.8.2) |
76 | goto &create; |
77 | } |
78 | |
79 | # Thread object equality checking |
80 | use overload ( |
81 | '==' => \&equal, |
82 | '!=' => sub { ! equal(@_) }, |
83 | 'fallback' => 1 |
84 | ); |
85 | |
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86 | 1; |
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87 | |
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88 | __END__ |
89 | |
90 | =head1 NAME |
91 | |
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92 | threads - Perl interpreter-based threads |
93 | |
94 | =head1 VERSION |
95 | |
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96 | This document describes threads version 1.24 |
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97 | |
98 | =head1 SYNOPSIS |
99 | |
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100 | use threads ('yield'); |
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101 | |
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102 | sub start_thread { |
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103 | my @args = @_; |
104 | print "Thread started: @args\n"; |
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105 | } |
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106 | my $thread = threads->create('start_thread', 'argument'); |
107 | $thread->join(); |
108 | |
109 | threads->create(sub { print("I am a thread\n"); })->join(); |
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110 | |
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111 | my $thread3 = async { foreach (@files) { ... } }; |
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112 | $thread3->join(); |
113 | |
114 | # Invoke thread in list context so it can return a list |
115 | my ($thr) = threads->create(sub { return (qw/a b c/); }); |
116 | my @results = $thr->join(); |
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117 | |
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118 | $thread->detach(); |
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119 | |
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120 | $thread = threads->self(); |
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121 | $thread = threads->object($tid); |
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122 | |
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123 | $tid = threads->tid(); |
124 | $tid = threads->self->tid(); |
125 | $tid = $thread->tid(); |
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126 | |
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127 | threads->yield(); |
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128 | yield(); |
129 | |
130 | my @threads = threads->list(); |
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131 | my $thread_count = threads->list(); |
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132 | |
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133 | if ($thr1 == $thr2) { |
134 | ... |
135 | } |
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136 | |
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137 | =head1 DESCRIPTION |
138 | |
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139 | Perl 5.6 introduced something called interpreter threads. Interpreter |
140 | threads are different from "5005threads" (the thread model of Perl |
141 | 5.005) by creating a new perl interpreter per thread and not sharing |
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142 | any data or state between threads by default. |
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143 | |
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144 | Prior to perl 5.8 this has only been available to people embedding |
145 | perl and for emulating fork() on windows. |
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146 | |
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147 | The threads API is loosely based on the old Thread.pm API. It is very |
148 | important to note that variables are not shared between threads, all |
149 | variables are per default thread local. To use shared variables one |
150 | must use threads::shared. |
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151 | |
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152 | It is also important to note that you must enable threads by doing |
153 | C<use threads> as early as possible in the script itself and that it |
154 | is not possible to enable threading inside an C<eval "">, C<do>, |
155 | C<require>, or C<use>. In particular, if you are intending to share |
156 | variables with threads::shared, you must C<use threads> before you |
157 | C<use threads::shared> and C<threads> will emit a warning if you do |
158 | it the other way around. |
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159 | |
160 | =over |
161 | |
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162 | =item $thr = threads->create(FUNCTION, ARGS) |
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163 | |
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164 | This will create a new thread that will begin execution with the specified |
165 | entry point function, and give it the I<ARGS> list as parameters. It will |
166 | return the corresponding threads object, or C<undef> if thread creation failed. |
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167 | |
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168 | I<FUNCTION> may either be the name of a function, an anonymous subroutine, or |
169 | a code ref. |
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170 | |
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171 | my $thr = threads->create('func_name', ...); |
172 | # or |
173 | my $thr = threads->create(sub { ... }, ...); |
174 | # or |
175 | my $thr = threads->create(\&func, ...); |
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176 | |
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177 | The thread may be created in I<list> context, or I<scalar> context as follows: |
178 | |
179 | # Create thread in list context |
180 | my ($thr) = threads->create(...); |
181 | |
182 | # Create thread in scalar context |
183 | my $thr = threads->create(...); |
184 | |
185 | This has consequences for the C<-E<gt>join()> method describe below. |
186 | |
187 | Although a thread may be created in I<void> context, to do so you must |
188 | I<chain> either the C<-E<gt>join()> or C<-E<gt>detach()> method to the |
189 | C<-E<gt>create()> call: |
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190 | |
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191 | threads->create(...)->join(); |
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192 | |
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193 | The C<-E<gt>new()> method is an alias for C<-E<gt>create()>. |
194 | |
195 | =item $thr->join() |
196 | |
197 | This will wait for the corresponding thread to complete its execution. When |
198 | the thread finishes, C<-E<gt>join()> will return the return value(s) of the |
199 | entry point function. |
200 | |
201 | The context (void, scalar or list) of the thread creation is also the |
202 | context for C<-E<gt>join()>. This means that if you intend to return an array |
203 | from a thread, you must use C<my ($thr) = threads->create(...)>, and that |
204 | if you intend to return a scalar, you must use C<my $thr = ...>: |
205 | |
206 | # Create thread in list context |
207 | my ($thr1) = threads->create(sub { |
208 | my @results = qw(a b c); |
209 | return (@results); |
210 | }; |
211 | # Retrieve list results from thread |
212 | my @res1 = $thr1->join(); |
213 | |
214 | # Create thread in scalar context |
215 | my $thr2 = threads->create(sub { |
216 | my $result = 42; |
217 | return ($result); |
218 | }; |
219 | # Retrieve scalar result from thread |
220 | my $res2 = $thr2->join(); |
221 | |
222 | If the program exits without all other threads having been either joined or |
223 | detached, then a warning will be issued. (A program exits either because one |
224 | of its threads explicitly calls L<exit()|perlfunc/"exit EXPR">, or in the case |
225 | of the main thread, reaches the end of the main program file.) |
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226 | |
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227 | Calling C<-E<gt>join()> or C<-E<gt>detach()> on an already joined thread will |
228 | cause an error to be thrown. |
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229 | |
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230 | =item $thr->detach() |
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231 | |
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232 | Makes the thread unjoinable, and causes any eventual return value to be |
233 | discarded. |
234 | |
235 | Calling C<-E<gt>join()> or C<-E<gt>detach()> on an already detached thread |
236 | will cause an error to be thrown. |
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237 | |
238 | =item threads->detach() |
239 | |
240 | Class method that allows a thread to detach itself. |
241 | |
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242 | =item threads->self() |
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243 | |
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244 | Class method that allows a thread to obtain its own I<threads> object. |
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245 | |
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246 | =item $thr->tid() |
247 | |
248 | Returns the ID of the thread. Thread IDs are unique integers with the main |
249 | thread in a program being 0, and incrementing by 1 for every thread created. |
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250 | |
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251 | =item threads->tid() |
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252 | |
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253 | Class method that allows a thread to obtain its own ID. |
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254 | |
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255 | =item threads->object($tid) |
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256 | |
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257 | This will return the I<threads> object for the I<active> thread associated |
258 | with the specified thread ID. Returns C<undef> if there is no thread |
259 | associated with the TID, if the thread is joined or detached, if no TID is |
260 | specified or if the specified TID is undef. |
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261 | |
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262 | =item threads->yield() |
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263 | |
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264 | This is a suggestion to the OS to let this thread yield CPU time to other |
265 | threads. What actually happens is highly dependent upon the underlying |
266 | thread implementation. |
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267 | |
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268 | You may do C<use threads qw(yield)>, and then just use C<yield()> in your |
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269 | code. |
270 | |
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271 | =item threads->list() |
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272 | |
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273 | In a list context, returns a list of all non-joined, non-detached I<threads> |
274 | objects. In a scalar context, returns a count of the same. |
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275 | |
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276 | =item $thr1->equal($thr2) |
277 | |
278 | Tests if two threads objects are the same thread or not. This is overloaded |
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279 | to the more natural forms: |
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280 | |
281 | if ($thr1 == $thr2) { |
282 | print("Threads are the same\n"); |
283 | } |
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284 | # or |
285 | if ($thr1 != $thr2) { |
286 | print("Threads differ\n"); |
287 | } |
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288 | |
289 | (Thread comparison is based on thread IDs.) |
290 | |
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291 | =item async BLOCK; |
292 | |
293 | C<async> creates a thread to execute the block immediately following |
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294 | it. This block is treated as an anonymous subroutine, and so must have a |
295 | semi-colon after the closing brace. Like C<threads->create()>, C<async> |
296 | returns a I<threads> object. |
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297 | |
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298 | =item $thr->_handle() |
299 | |
300 | This I<private> method returns the memory location of the internal thread |
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301 | structure associated with a threads object. For Win32, this is a pointer to |
302 | the C<HANDLE> value returned by C<CreateThread> (i.e., C<HANDLE *>); for other |
303 | platforms, it is a pointer to the C<pthread_t> structure used in the |
304 | C<pthread_create> call (i.e., C<pthread_t *>. |
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305 | |
306 | This method is of no use for general Perl threads programming. Its intent is |
307 | to provide other (XS-based) thread modules with the capability to access, and |
308 | possibly manipulate, the underlying thread structure associated with a Perl |
309 | thread. |
310 | |
311 | =item threads->_handle() |
312 | |
313 | Class method that allows a thread to obtain its own I<handle>. |
314 | |
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315 | =back |
316 | |
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317 | =head1 WARNINGS |
318 | |
319 | =over 4 |
320 | |
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321 | =item A thread exited while # other threads were still running |
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322 | |
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323 | A thread (not necessarily the main thread) exited while there were |
324 | still other threads running. Usually it's a good idea to first collect |
325 | the return values of the created threads by joining them, and only then |
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326 | exit from the main thread. |
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327 | |
328 | =back |
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329 | |
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330 | =head1 ERRORS |
331 | |
332 | =over 4 |
333 | |
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334 | =item This Perl not built to support threads |
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335 | |
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336 | The particular copy of Perl that you're trying to use was not built using the |
337 | C<useithreads> configuration option. |
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338 | |
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339 | Having threads support requires all of Perl and all of the XS modules in the |
340 | Perl installation to be rebuilt; it is not just a question of adding the |
341 | L<threads> module (i.e., threaded and non-threaded Perls are binary |
342 | incompatible.) |
343 | |
344 | =back |
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345 | |
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346 | =head1 BUGS |
347 | |
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348 | =over |
349 | |
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350 | =item Parent-child threads |
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351 | |
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352 | On some platforms, it might not be possible to destroy I<parent> threads while |
353 | there are still existing I<child> threads. |
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354 | |
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355 | =item Creating threads inside BEGIN blocks |
356 | |
357 | Creating threads inside BEGIN blocks (or during the compilation phase |
358 | in general) does not work. (In Windows, trying to use fork() inside |
359 | BEGIN blocks is an equally losing proposition, since it has been |
360 | implemented in very much the same way as threads.) |
361 | |
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362 | =item PERL_OLD_SIGNALS are not threadsafe, will not be. |
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363 | |
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364 | If your Perl has been built with PERL_OLD_SIGNALS (one has |
365 | to explicitly add that symbol to ccflags, see C<perl -V>), |
366 | signal handling is not threadsafe. |
367 | |
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368 | =item Returning closures from threads |
369 | |
370 | Returning a closure from a thread does not work, usually crashing Perl in the |
371 | process. |
372 | |
373 | =item Perl Bugs and the CPAN Version of L<threads> |
374 | |
375 | Support for threads extents beyond the code in this module (i.e., |
376 | F<threads.pm> and F<threads.xs>), and into the Perl iterpreter itself. Older |
377 | versions of Perl contain bugs that may manifest themselves despite using the |
378 | latest version of L<threads> from CPAN. There is no workaround for this other |
379 | than upgrading to the lastest version of Perl. |
380 | |
381 | (Before you consider posting a bug report, please consult, and possibly post a |
382 | message to the discussion forum to see if what you've encountered is a known |
383 | problem.) |
384 | |
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385 | =back |
386 | |
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387 | =head1 REQUIREMENTS |
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388 | |
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389 | Perl 5.8.0 or later |
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390 | |
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391 | =head1 SEE ALSO |
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392 | |
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393 | L<threads> Discussion Forum on CPAN: |
394 | L<http://www.cpanforum.com/dist/threads> |
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395 | |
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396 | Annotated POD for L<threads>: |
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397 | L<http://annocpan.org/~JDHEDDEN/threads-1.24/shared.pm> |
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398 | |
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399 | L<threads::shared>, L<perlthrtut> |
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400 | |
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401 | L<http://www.perl.com/pub/a/2002/06/11/threads.html> and |
402 | L<http://www.perl.com/pub/a/2002/09/04/threads.html> |
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403 | |
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404 | Perl threads mailing list: |
405 | L<http://lists.cpan.org/showlist.cgi?name=iThreads> |
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406 | |
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407 | =head1 AUTHOR |
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408 | |
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409 | Artur Bergman E<lt>sky AT crucially DOT netE<gt> |
410 | |
411 | threads is released under the same license as Perl. |
412 | |
413 | CPAN version produced by Jerry D. Hedden <jdhedden AT cpan DOT org> |
414 | |
415 | =head1 ACKNOWLEDGEMENTS |
416 | |
417 | Richard Soderberg E<lt>perl AT crystalflame DOT netE<gt> - |
418 | Helping me out tons, trying to find reasons for races and other weird bugs! |
419 | |
420 | Simon Cozens E<lt>simon AT brecon DOT co DOT ukE<gt> - |
421 | Being there to answer zillions of annoying questions |
422 | |
423 | Rocco Caputo E<lt>troc AT netrus DOT netE<gt> |
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424 | |
0f1612a7 |
425 | Vipul Ved Prakash E<lt>mail AT vipul DOT netE<gt> - |
426 | Helping with debugging |
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427 | |
428 | =cut |