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1 | package threads; |
2 | |
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3 | use 5.008; |
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4 | use strict; |
5 | use warnings; |
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6 | use Config; |
7 | |
8 | BEGIN { |
9 | unless ($Config{useithreads}) { |
10 | my @caller = caller(2); |
11 | die <<EOF; |
12 | $caller[1] line $caller[2]: |
13 | |
14 | This Perl hasn't been configured and built properly for the threads |
15 | module to work. (The 'useithreads' configuration option hasn't been used.) |
16 | |
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17 | Having threads support requires all of Perl and all of the XS modules in |
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18 | the Perl installation to be rebuilt, it is not just a question of adding |
19 | the threads module. (In other words, threaded and non-threaded Perls |
20 | are binary incompatible.) |
21 | |
22 | If you want to the use the threads module, please contact the people |
23 | who built your Perl. |
24 | |
25 | Cannot continue, aborting. |
26 | EOF |
27 | } |
28 | } |
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29 | |
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30 | use overload |
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31 | '==' => \&equal, |
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32 | 'fallback' => 1; |
33 | |
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34 | BEGIN { |
35 | warn "Warning, threads::shared has already been loaded. ". |
36 | "To enable shared variables for these modules 'use threads' ". |
37 | "must be called before any of those modules are loaded\n" |
38 | if($threads::shared::threads_shared); |
39 | } |
40 | |
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41 | require Exporter; |
42 | require DynaLoader; |
43 | |
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44 | our @ISA = qw(Exporter DynaLoader); |
45 | |
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46 | our %EXPORT_TAGS = ( all => [qw(yield)]); |
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47 | |
48 | our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } ); |
49 | |
50 | our @EXPORT = qw( |
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51 | async |
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52 | ); |
ff270add |
53 | our $VERSION = '1.04'; |
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54 | |
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55 | |
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56 | # || 0 to ensure compatibility with previous versions |
57 | sub equal { ($_[0]->tid == $_[1]->tid) || 0 } |
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58 | |
c3697438 |
59 | # use "goto" trick to avoid pad problems from 5.8.1 (fixed in 5.8.2) |
60 | # should also be faster |
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61 | sub async (&;@) { unshift @_,'threads'; goto &new } |
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62 | |
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63 | sub object { |
64 | return undef unless @_ > 1; |
65 | foreach (threads->list) { |
66 | return $_ if $_->tid == $_[1]; |
67 | } |
68 | return undef; |
69 | } |
70 | |
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71 | $threads::threads = 1; |
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72 | |
73 | bootstrap threads $VERSION; |
74 | |
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75 | # why document 'new' then use 'create' in the tests! |
76 | *create = \&new; |
77 | |
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78 | # Preloaded methods go here. |
79 | |
80 | 1; |
81 | __END__ |
82 | |
83 | =head1 NAME |
84 | |
85 | threads - Perl extension allowing use of interpreter based threads from perl |
86 | |
87 | =head1 SYNOPSIS |
88 | |
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89 | use threads; |
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90 | |
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91 | sub start_thread { |
92 | print "Thread started\n"; |
93 | } |
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94 | |
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95 | my $thread = threads->create("start_thread","argument"); |
96 | my $thread2 = $thread->create(sub { print "I am a thread"},"argument"); |
97 | my $thread3 = async { foreach (@files) { ... } }; |
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98 | |
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99 | $thread->join(); |
100 | $thread->detach(); |
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101 | |
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102 | $thread = threads->self(); |
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103 | $thread = threads->object( $tid ); |
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104 | |
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105 | $thread->tid(); |
106 | threads->tid(); |
107 | threads->self->tid(); |
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108 | |
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109 | threads->yield(); |
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110 | |
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111 | threads->list(); |
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112 | |
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113 | =head1 DESCRIPTION |
114 | |
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115 | Perl 5.6 introduced something called interpreter threads. Interpreter |
116 | threads are different from "5005threads" (the thread model of Perl |
117 | 5.005) by creating a new perl interpreter per thread and not sharing |
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118 | any data or state between threads by default. |
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119 | |
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120 | Prior to perl 5.8 this has only been available to people embedding |
121 | perl and for emulating fork() on windows. |
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122 | |
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123 | The threads API is loosely based on the old Thread.pm API. It is very |
124 | important to note that variables are not shared between threads, all |
125 | variables are per default thread local. To use shared variables one |
126 | must use threads::shared. |
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127 | |
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128 | It is also important to note that you must enable threads by doing |
129 | C<use threads> as early as possible in the script itself and that it |
130 | is not possible to enable threading inside an C<eval "">, C<do>, |
131 | C<require>, or C<use>. In particular, if you are intending to share |
132 | variables with threads::shared, you must C<use threads> before you |
133 | C<use threads::shared> and C<threads> will emit a warning if you do |
134 | it the other way around. |
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135 | |
136 | =over |
137 | |
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138 | =item $thread = threads->create(function, LIST) |
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139 | |
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140 | This will create a new thread with the entry point function and give |
141 | it LIST as parameters. It will return the corresponding threads |
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142 | object. The new() method is an alias for create(). |
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143 | |
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144 | =item $thread->join |
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145 | |
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146 | This will wait for the corresponding thread to join. When the thread |
147 | finishes, join() will return the return values of the entry point |
148 | function. If the thread has been detached, an error will be thrown. |
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149 | |
150 | The context (scalar or list) of the thread creation is also the |
151 | context for join(). This means that if you intend to return an array |
152 | from a thread, you must use C<my ($thread) = threads->new(...)>, and |
153 | that if you intend to return a scalar, you must use C<my $thread = ...>. |
154 | |
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155 | If the program exits without all other threads having been either |
156 | joined or detached, then a warning will be issued. (A program exits |
157 | either because one of its threads explicitly calls exit(), or in the |
158 | case of the main thread, reaches the end of the main program file.) |
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159 | |
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160 | |
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161 | =item $thread->detach |
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162 | |
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163 | Will make the thread unjoinable, and cause any eventual return value |
164 | to be discarded. |
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165 | |
166 | =item threads->self |
167 | |
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168 | This will return the thread object for the current thread. |
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169 | |
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170 | =item $thread->tid |
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171 | |
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172 | This will return the id of the thread. Thread IDs are integers, with |
173 | the main thread in a program being 0. Currently Perl assigns a unique |
174 | tid to every thread ever created in your program, assigning the first |
175 | thread to be created a tid of 1, and increasing the tid by 1 for each |
176 | new thread that's created. |
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177 | |
178 | NB the class method C<< threads->tid() >> is a quick way to get the |
179 | current thread id if you don't have your thread object handy. |
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180 | |
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181 | =item threads->object( tid ) |
182 | |
183 | This will return the thread object for the thread associated with the |
184 | specified tid. Returns undef if there is no thread associated with the tid |
185 | or no tid is specified or the specified tid is undef. |
186 | |
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187 | =item threads->yield(); |
188 | |
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189 | This is a suggestion to the OS to let this thread yield CPU time to other |
190 | threads. What actually happens is highly dependent upon the underlying |
191 | thread implementation. |
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192 | |
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193 | You may do C<use threads qw(yield)> then use just a bare C<yield> in your |
194 | code. |
195 | |
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196 | =item threads->list(); |
197 | |
198 | This will return a list of all non joined, non detached threads. |
199 | |
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200 | =item async BLOCK; |
201 | |
202 | C<async> creates a thread to execute the block immediately following |
203 | it. This block is treated as an anonymous sub, and so must have a |
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204 | semi-colon after the closing brace. Like C<< threads->new >>, C<async> |
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205 | returns a thread object. |
206 | |
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207 | =back |
208 | |
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209 | =head1 WARNINGS |
210 | |
211 | =over 4 |
212 | |
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213 | =item A thread exited while %d other threads were still running |
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214 | |
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215 | A thread (not necessarily the main thread) exited while there were |
216 | still other threads running. Usually it's a good idea to first collect |
217 | the return values of the created threads by joining them, and only then |
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218 | exit from the main thread. |
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219 | |
220 | =back |
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221 | |
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222 | =head1 TODO |
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223 | |
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224 | The current implementation of threads has been an attempt to get |
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225 | a correct threading system working that could be built on, |
226 | and optimized, in newer versions of perl. |
227 | |
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228 | Currently the overhead of creating a thread is rather large, |
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229 | also the cost of returning values can be large. These are areas |
230 | were there most likely will be work done to optimize what data |
231 | that needs to be cloned. |
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232 | |
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233 | =head1 BUGS |
234 | |
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235 | =over |
236 | |
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237 | =item Parent-Child threads. |
238 | |
239 | On some platforms it might not be possible to destroy "parent" |
240 | threads while there are still existing child "threads". |
241 | |
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242 | This will possibly be fixed in later versions of perl. |
243 | |
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244 | =item tid is I32 |
245 | |
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246 | The thread id is a 32 bit integer, it can potentially overflow. |
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247 | This might be fixed in a later version of perl. |
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248 | |
678a9b6c |
249 | =item Returning objects |
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250 | |
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251 | When you return an object the entire stash that the object is blessed |
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252 | as well. This will lead to a large memory usage. The ideal situation |
253 | would be to detect the original stash if it existed. |
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254 | |
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255 | =item Creating threads inside BEGIN blocks |
256 | |
257 | Creating threads inside BEGIN blocks (or during the compilation phase |
258 | in general) does not work. (In Windows, trying to use fork() inside |
259 | BEGIN blocks is an equally losing proposition, since it has been |
260 | implemented in very much the same way as threads.) |
261 | |
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262 | =item PERL_OLD_SIGNALS are not threadsafe, will not be. |
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263 | |
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264 | If your Perl has been built with PERL_OLD_SIGNALS (one has |
265 | to explicitly add that symbol to ccflags, see C<perl -V>), |
266 | signal handling is not threadsafe. |
267 | |
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268 | =back |
269 | |
270 | =head1 AUTHOR and COPYRIGHT |
271 | |
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272 | Arthur Bergman E<lt>sky at nanisky.comE<gt> |
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273 | |
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274 | threads is released under the same license as Perl. |
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275 | |
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276 | Thanks to |
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277 | |
ca9279ba |
278 | Richard Soderberg E<lt>perl at crystalflame.netE<gt> |
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279 | Helping me out tons, trying to find reasons for races and other weird bugs! |
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280 | |
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281 | Simon Cozens E<lt>simon at brecon.co.ukE<gt> |
282 | Being there to answer zillions of annoying questions |
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283 | |
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284 | Rocco Caputo E<lt>troc at netrus.netE<gt> |
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285 | |
ad91d581 |
286 | Vipul Ved Prakash E<lt>mail at vipul.netE<gt> |
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287 | Helping with debugging. |
288 | |
289 | please join perl-ithreads@perl.org for more information |
290 | |
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291 | =head1 SEE ALSO |
292 | |
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293 | L<threads::shared>, L<perlthrtut>, |
294 | L<http://www.perl.com/pub/a/2002/06/11/threads.html>, |
295 | L<perlcall>, L<perlembed>, L<perlguts> |
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296 | |
297 | =cut |