… | |
… | |
27 | |
27 | |
28 | Special care has been taken to make this module useful from other modules, |
28 | Special care has been taken to make this module useful from other modules, |
29 | while still supporting specialised environments such as L<App::Staticperl> |
29 | while still supporting specialised environments such as L<App::Staticperl> |
30 | or L<PAR::Packer>. |
30 | or L<PAR::Packer>. |
31 | |
31 | |
32 | =head1 WHAT THIS MODULE IS NOT |
32 | =head2 WHAT THIS MODULE IS NOT |
33 | |
33 | |
34 | This module only creates processes and lets you pass file handles and |
34 | This module only creates processes and lets you pass file handles and |
35 | strings to it, and run perl code. It does not implement any kind of RPC - |
35 | strings to it, and run perl code. It does not implement any kind of RPC - |
36 | there is no back channel from the process back to you, and there is no RPC |
36 | there is no back channel from the process back to you, and there is no RPC |
37 | or message passing going on. |
37 | or message passing going on. |
38 | |
38 | |
39 | If you need some form of RPC, you can either implement it yourself |
39 | If you need some form of RPC, you could use the L<AnyEvent::Fork::RPC> |
40 | in whatever way you like, use some message-passing module such |
40 | companion module, which adds simple RPC/job queueing to a process created |
41 | as L<AnyEvent::MP>, some pipe such as L<AnyEvent::ZeroMQ>, use |
41 | by this module. |
42 | L<AnyEvent::Handle> on both sides to send e.g. JSON or Storable messages, |
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43 | and so on. |
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44 | |
42 | |
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43 | And if you need some automatic process pool management on top of |
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44 | L<AnyEvent::Fork::RPC>, you can look at the L<AnyEvent::Fork::Pool> |
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45 | companion module. |
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46 | |
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47 | Or you can implement it yourself in whatever way you like: use some |
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48 | message-passing module such as L<AnyEvent::MP>, some pipe such as |
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49 | L<AnyEvent::ZeroMQ>, use L<AnyEvent::Handle> on both sides to send |
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50 | e.g. JSON or Storable messages, and so on. |
|
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51 | |
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52 | =head2 COMPARISON TO OTHER MODULES |
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53 | |
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54 | There is an abundance of modules on CPAN that do "something fork", such as |
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55 | L<Parallel::ForkManager>, L<AnyEvent::ForkManager>, L<AnyEvent::Worker> |
|
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56 | or L<AnyEvent::Subprocess>. There are modules that implement their own |
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57 | process management, such as L<AnyEvent::DBI>. |
|
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58 | |
|
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59 | The problems that all these modules try to solve are real, however, none |
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60 | of them (from what I have seen) tackle the very real problems of unwanted |
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61 | memory sharing, efficiency or not being able to use event processing, GUI |
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62 | toolkits or similar modules in the processes they create. |
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63 | |
|
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64 | This module doesn't try to replace any of them - instead it tries to solve |
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65 | the problem of creating processes with a minimum of fuss and overhead (and |
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66 | also luxury). Ideally, most of these would use AnyEvent::Fork internally, |
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67 | except they were written before AnyEvent:Fork was available, so obviously |
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68 | had to roll their own. |
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69 | |
45 | =head1 PROBLEM STATEMENT |
70 | =head2 PROBLEM STATEMENT |
46 | |
71 | |
47 | There are two traditional ways to implement parallel processing on UNIX |
72 | There are two traditional ways to implement parallel processing on UNIX |
48 | like operating systems - fork and process, and fork+exec and process. They |
73 | like operating systems - fork and process, and fork+exec and process. They |
49 | have different advantages and disadvantages that I describe below, |
74 | have different advantages and disadvantages that I describe below, |
50 | together with how this module tries to mitigate the disadvantages. |
75 | together with how this module tries to mitigate the disadvantages. |
… | |
… | |
64 | |
89 | |
65 | =item Forking usually creates a copy-on-write copy of the parent |
90 | =item Forking usually creates a copy-on-write copy of the parent |
66 | process. |
91 | process. |
67 | |
92 | |
68 | For example, modules or data files that are loaded will not use additional |
93 | For example, modules or data files that are loaded will not use additional |
69 | memory after a fork. When exec'ing a new process, modules and data files |
94 | memory after a fork. Exec'ing a new process, in contrast, means modules |
70 | might need to be loaded again, at extra CPU and memory cost. But when |
95 | and data files might need to be loaded again, at extra CPU and memory |
71 | forking, literally all data structures are copied - if the program frees |
96 | cost. |
|
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97 | |
|
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98 | But when forking, you still create a copy of your data structures - if |
72 | them and replaces them by new data, the child processes will retain the |
99 | the program frees them and replaces them by new data, the child processes |
73 | old version even if it isn't used, which can suddenly and unexpectedly |
100 | will retain the old version even if it isn't used, which can suddenly and |
74 | increase memory usage when freeing memory. |
101 | unexpectedly increase memory usage when freeing memory. |
75 | |
102 | |
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103 | For example, L<Gtk2::CV> is an image viewer optimised for large |
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104 | directories (millions of pictures). It also forks subprocesses for |
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105 | thumbnail generation, which inherit the data structure that stores all |
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106 | file information. If the user changes the directory, it gets freed in |
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107 | the main process, leaving a copy in the thumbnailer processes. This can |
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108 | lead to many times the memory usage that would actually be required. The |
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109 | solution is to fork early (and being unable to dynamically generate more |
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110 | subprocesses or do this from a module)... or to use L<AnyEvent:Fork>. |
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111 | |
76 | The trade-off is between more sharing with fork (which can be good or |
112 | There is a trade-off between more sharing with fork (which can be good or |
77 | bad), and no sharing with exec. |
113 | bad), and no sharing with exec. |
78 | |
114 | |
79 | This module allows the main program to do a controlled fork, and allows |
115 | This module allows the main program to do a controlled fork, and allows |
80 | modules to exec processes safely at any time. When creating a custom |
116 | modules to exec processes safely at any time. When creating a custom |
81 | process pool you can take advantage of data sharing via fork without |
117 | process pool you can take advantage of data sharing via fork without |
… | |
… | |
86 | shared and what isn't, at all times. |
122 | shared and what isn't, at all times. |
87 | |
123 | |
88 | =item Exec'ing a new perl process might be difficult. |
124 | =item Exec'ing a new perl process might be difficult. |
89 | |
125 | |
90 | For example, it is not easy to find the correct path to the perl |
126 | For example, it is not easy to find the correct path to the perl |
91 | interpreter - C<$^X> might not be a perl interpreter at all. |
127 | interpreter - C<$^X> might not be a perl interpreter at all. Worse, there |
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128 | might not even be a perl binary installed on the system. |
92 | |
129 | |
93 | This module tries hard to identify the correct path to the perl |
130 | This module tries hard to identify the correct path to the perl |
94 | interpreter. With a cooperative main program, exec'ing the interpreter |
131 | interpreter. With a cooperative main program, exec'ing the interpreter |
95 | might not even be necessary, but even without help from the main program, |
132 | might not even be necessary, but even without help from the main program, |
96 | it will still work when used from a module. |
133 | it will still work when used from a module. |
… | |
… | |
102 | and modules are no longer loadable because they refer to a different |
139 | and modules are no longer loadable because they refer to a different |
103 | perl version, or parts of a distribution are newer than the ones already |
140 | perl version, or parts of a distribution are newer than the ones already |
104 | loaded. |
141 | loaded. |
105 | |
142 | |
106 | This module supports creating pre-initialised perl processes to be used as |
143 | This module supports creating pre-initialised perl processes to be used as |
107 | a template for new processes. |
144 | a template for new processes at a later time, e.g. for use in a process |
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145 | pool. |
108 | |
146 | |
109 | =item Forking might be impossible when a program is running. |
147 | =item Forking might be impossible when a program is running. |
110 | |
148 | |
111 | For example, POSIX makes it almost impossible to fork from a |
149 | For example, POSIX makes it almost impossible to fork from a |
112 | multi-threaded program while doing anything useful in the child - in |
150 | multi-threaded program while doing anything useful in the child - in |
113 | fact, if your perl program uses POSIX threads (even indirectly via |
151 | fact, if your perl program uses POSIX threads (even indirectly via |
114 | e.g. L<IO::AIO> or L<threads>), you cannot call fork on the perl level |
152 | e.g. L<IO::AIO> or L<threads>), you cannot call fork on the perl level |
115 | anymore without risking corruption issues on a number of operating |
153 | anymore without risking memory corruption or worse on a number of |
116 | systems. |
154 | operating systems. |
117 | |
155 | |
118 | This module can safely fork helper processes at any time, by calling |
156 | This module can safely fork helper processes at any time, by calling |
119 | fork+exec in C, in a POSIX-compatible way (via L<Proc::FastSpawn>). |
157 | fork+exec in C, in a POSIX-compatible way (via L<Proc::FastSpawn>). |
120 | |
158 | |
121 | =item Parallel processing with fork might be inconvenient or difficult |
159 | =item Parallel processing with fork might be inconvenient or difficult |
… | |
… | |
140 | |
178 | |
141 | =back |
179 | =back |
142 | |
180 | |
143 | =head1 EXAMPLES |
181 | =head1 EXAMPLES |
144 | |
182 | |
|
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183 | This is where the wall of text ends and code speaks. |
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184 | |
145 | =head2 Create a single new process, tell it to run your worker function. |
185 | =head2 Create a single new process, tell it to run your worker function. |
146 | |
186 | |
147 | AnyEvent::Fork |
187 | AnyEvent::Fork |
148 | ->new |
188 | ->new |
149 | ->require ("MyModule") |
189 | ->require ("MyModule") |
… | |
… | |
160 | |
200 | |
161 | sub worker { |
201 | sub worker { |
162 | my ($slave_filehandle) = @_; |
202 | my ($slave_filehandle) = @_; |
163 | |
203 | |
164 | # now $slave_filehandle is connected to the $master_filehandle |
204 | # now $slave_filehandle is connected to the $master_filehandle |
165 | # in the original prorcess. have fun! |
205 | # in the original process. have fun! |
166 | } |
206 | } |
167 | |
207 | |
168 | =head2 Create a pool of server processes all accepting on the same socket. |
208 | =head2 Create a pool of server processes all accepting on the same socket. |
169 | |
209 | |
170 | # create listener socket |
210 | # create listener socket |
… | |
… | |
203 | } |
243 | } |
204 | } |
244 | } |
205 | |
245 | |
206 | =head2 use AnyEvent::Fork as a faster fork+exec |
246 | =head2 use AnyEvent::Fork as a faster fork+exec |
207 | |
247 | |
208 | This runs C</bin/echo hi>, with stdandard output redirected to /tmp/log |
248 | This runs C</bin/echo hi>, with standard output redirected to F</tmp/log> |
209 | and standard error redirected to the communications socket. It is usually |
249 | and standard error redirected to the communications socket. It is usually |
210 | faster than fork+exec, but still lets you prepare the environment. |
250 | faster than fork+exec, but still lets you prepare the environment. |
211 | |
251 | |
212 | open my $output, ">/tmp/log" or die "$!"; |
252 | open my $output, ">/tmp/log" or die "$!"; |
213 | |
253 | |
214 | AnyEvent::Fork |
254 | AnyEvent::Fork |
215 | ->new |
255 | ->new |
216 | ->eval (' |
256 | ->eval (' |
|
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257 | # compile a helper function for later use |
217 | sub run { |
258 | sub run { |
218 | my ($fh, $output, @cmd) = @_; |
259 | my ($fh, $output, @cmd) = @_; |
219 | |
260 | |
220 | # perl will clear close-on-exec on STDOUT/STDERR |
261 | # perl will clear close-on-exec on STDOUT/STDERR |
221 | open STDOUT, ">&", $output or die; |
262 | open STDOUT, ">&", $output or die; |
… | |
… | |
228 | ->send_arg ("/bin/echo", "hi") |
269 | ->send_arg ("/bin/echo", "hi") |
229 | ->run ("run", my $cv = AE::cv); |
270 | ->run ("run", my $cv = AE::cv); |
230 | |
271 | |
231 | my $stderr = $cv->recv; |
272 | my $stderr = $cv->recv; |
232 | |
273 | |
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274 | =head2 For stingy users: put the worker code into a C<DATA> section. |
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275 | |
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276 | When you want to be stingy with files, you can put your code into the |
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277 | C<DATA> section of your module (or program): |
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278 | |
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279 | use AnyEvent::Fork; |
|
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280 | |
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281 | AnyEvent::Fork |
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282 | ->new |
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283 | ->eval (do { local $/; <DATA> }) |
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284 | ->run ("doit", sub { ... }); |
|
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285 | |
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286 | __DATA__ |
|
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287 | |
|
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288 | sub doit { |
|
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289 | ... do something! |
|
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290 | } |
|
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291 | |
|
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292 | =head2 For stingy standalone programs: do not rely on external files at |
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293 | all. |
|
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294 | |
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295 | For single-file scripts it can be inconvenient to rely on external |
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296 | files - even when using a C<DATA> section, you still need to C<exec> an |
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297 | external perl interpreter, which might not be available when using |
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298 | L<App::Staticperl>, L<Urlader> or L<PAR::Packer> for example. |
|
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299 | |
|
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300 | Two modules help here - L<AnyEvent::Fork::Early> forks a template process |
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301 | for all further calls to C<new_exec>, and L<AnyEvent::Fork::Template> |
|
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302 | forks the main program as a template process. |
|
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303 | |
|
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304 | Here is how your main program should look like: |
|
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305 | |
|
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306 | #! perl |
|
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307 | |
|
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308 | # optional, as the very first thing. |
|
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309 | # in case modules want to create their own processes. |
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310 | use AnyEvent::Fork::Early; |
|
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311 | |
|
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312 | # next, load all modules you need in your template process |
|
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313 | use Example::My::Module |
|
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314 | use Example::Whatever; |
|
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315 | |
|
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316 | # next, put your run function definition and anything else you |
|
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317 | # need, but do not use code outside of BEGIN blocks. |
|
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318 | sub worker_run { |
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319 | my ($fh, @args) = @_; |
|
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320 | ... |
|
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321 | } |
|
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322 | |
|
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323 | # now preserve everything so far as AnyEvent::Fork object |
|
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324 | # in $TEMPLATE. |
|
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325 | use AnyEvent::Fork::Template; |
|
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326 | |
|
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327 | # do not put code outside of BEGIN blocks until here |
|
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328 | |
|
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329 | # now use the $TEMPLATE process in any way you like |
|
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330 | |
|
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331 | # for example: create 10 worker processes |
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332 | my @worker; |
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333 | my $cv = AE::cv; |
|
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334 | for (1..10) { |
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335 | $cv->begin; |
|
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336 | $TEMPLATE->fork->send_arg ($_)->run ("worker_run", sub { |
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337 | push @worker, shift; |
|
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338 | $cv->end; |
|
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339 | }); |
|
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340 | } |
|
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341 | $cv->recv; |
|
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342 | |
233 | =head1 CONCEPTS |
343 | =head1 CONCEPTS |
234 | |
344 | |
235 | This module can create new processes either by executing a new perl |
345 | This module can create new processes either by executing a new perl |
236 | process, or by forking from an existing "template" process. |
346 | process, or by forking from an existing "template" process. |
|
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347 | |
|
|
348 | All these processes are called "child processes" (whether they are direct |
|
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349 | children or not), while the process that manages them is called the |
|
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350 | "parent process". |
237 | |
351 | |
238 | Each such process comes with its own file handle that can be used to |
352 | Each such process comes with its own file handle that can be used to |
239 | communicate with it (it's actually a socket - one end in the new process, |
353 | communicate with it (it's actually a socket - one end in the new process, |
240 | one end in the main process), and among the things you can do in it are |
354 | one end in the main process), and among the things you can do in it are |
241 | load modules, fork new processes, send file handles to it, and execute |
355 | load modules, fork new processes, send file handles to it, and execute |
… | |
… | |
351 | use AnyEvent; |
465 | use AnyEvent; |
352 | use AnyEvent::Util (); |
466 | use AnyEvent::Util (); |
353 | |
467 | |
354 | use IO::FDPass; |
468 | use IO::FDPass; |
355 | |
469 | |
356 | our $VERSION = 0.5; |
470 | our $VERSION = 1.2; |
357 | |
|
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358 | our $PERL; # the path to the perl interpreter, deduces with various forms of magic |
|
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359 | |
|
|
360 | =over 4 |
|
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361 | |
|
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362 | =back |
|
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363 | |
|
|
364 | =cut |
|
|
365 | |
471 | |
366 | # the early fork template process |
472 | # the early fork template process |
367 | our $EARLY; |
473 | our $EARLY; |
368 | |
474 | |
369 | # the empty template process |
475 | # the empty template process |
370 | our $TEMPLATE; |
476 | our $TEMPLATE; |
|
|
477 | |
|
|
478 | sub QUEUE() { 0 } |
|
|
479 | sub FH() { 1 } |
|
|
480 | sub WW() { 2 } |
|
|
481 | sub PID() { 3 } |
|
|
482 | sub CB() { 4 } |
|
|
483 | |
|
|
484 | sub _new { |
|
|
485 | my ($self, $fh, $pid) = @_; |
|
|
486 | |
|
|
487 | AnyEvent::Util::fh_nonblocking $fh, 1; |
|
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488 | |
|
|
489 | $self = bless [ |
|
|
490 | [], # write queue - strings or fd's |
|
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491 | $fh, |
|
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492 | undef, # AE watcher |
|
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493 | $pid, |
|
|
494 | ], $self; |
|
|
495 | |
|
|
496 | $self |
|
|
497 | } |
371 | |
498 | |
372 | sub _cmd { |
499 | sub _cmd { |
373 | my $self = shift; |
500 | my $self = shift; |
374 | |
501 | |
375 | # ideally, we would want to use "a (w/a)*" as format string, but perl |
502 | # ideally, we would want to use "a (w/a)*" as format string, but perl |
376 | # versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack |
503 | # versions from at least 5.8.9 to 5.16.3 are all buggy and can't unpack |
377 | # it. |
504 | # it. |
378 | push @{ $self->[2] }, pack "a L/a*", $_[0], $_[1]; |
505 | push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1]; |
379 | |
506 | |
380 | $self->[3] ||= AE::io $self->[1], 1, sub { |
507 | $self->[WW] ||= AE::io $self->[FH], 1, sub { |
381 | do { |
508 | do { |
382 | # send the next "thing" in the queue - either a reference to an fh, |
509 | # send the next "thing" in the queue - either a reference to an fh, |
383 | # or a plain string. |
510 | # or a plain string. |
384 | |
511 | |
385 | if (ref $self->[2][0]) { |
512 | if (ref $self->[QUEUE][0]) { |
386 | # send fh |
513 | # send fh |
387 | unless (IO::FDPass::send fileno $self->[1], fileno ${ $self->[2][0] }) { |
514 | unless (IO::FDPass::send fileno $self->[FH], fileno ${ $self->[QUEUE][0] }) { |
388 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
515 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
389 | undef $self->[3]; |
516 | undef $self->[WW]; |
390 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
517 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
391 | } |
518 | } |
392 | |
519 | |
393 | shift @{ $self->[2] }; |
520 | shift @{ $self->[QUEUE] }; |
394 | |
521 | |
395 | } else { |
522 | } else { |
396 | # send string |
523 | # send string |
397 | my $len = syswrite $self->[1], $self->[2][0]; |
524 | my $len = syswrite $self->[FH], $self->[QUEUE][0]; |
398 | |
525 | |
399 | unless ($len) { |
526 | unless ($len) { |
400 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
527 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
401 | undef $self->[3]; |
528 | undef $self->[WW]; |
402 | die "AnyEvent::Fork: command write failure: $!"; |
529 | die "AnyEvent::Fork: command write failure: $!"; |
403 | } |
530 | } |
404 | |
531 | |
405 | substr $self->[2][0], 0, $len, ""; |
532 | substr $self->[QUEUE][0], 0, $len, ""; |
406 | shift @{ $self->[2] } unless length $self->[2][0]; |
533 | shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0]; |
407 | } |
534 | } |
408 | } while @{ $self->[2] }; |
535 | } while @{ $self->[QUEUE] }; |
409 | |
536 | |
410 | # everything written |
537 | # everything written |
411 | undef $self->[3]; |
538 | undef $self->[WW]; |
412 | |
539 | |
413 | # invoke run callback, if any |
540 | # invoke run callback, if any |
414 | $self->[4]->($self->[1]) if $self->[4]; |
541 | if ($self->[CB]) { |
|
|
542 | $self->[CB]->($self->[FH]); |
|
|
543 | @$self = (); |
|
|
544 | } |
415 | }; |
545 | }; |
416 | |
546 | |
417 | () # make sure we don't leak the watcher |
547 | () # make sure we don't leak the watcher |
418 | } |
|
|
419 | |
|
|
420 | sub _new { |
|
|
421 | my ($self, $fh, $pid) = @_; |
|
|
422 | |
|
|
423 | AnyEvent::Util::fh_nonblocking $fh, 1; |
|
|
424 | |
|
|
425 | $self = bless [ |
|
|
426 | $pid, |
|
|
427 | $fh, |
|
|
428 | [], # write queue - strings or fd's |
|
|
429 | undef, # AE watcher |
|
|
430 | ], $self; |
|
|
431 | |
|
|
432 | $self |
|
|
433 | } |
548 | } |
434 | |
549 | |
435 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
550 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
436 | sub _new_fork { |
551 | sub _new_fork { |
437 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
552 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
… | |
… | |
442 | if ($pid eq 0) { |
557 | if ($pid eq 0) { |
443 | require AnyEvent::Fork::Serve; |
558 | require AnyEvent::Fork::Serve; |
444 | $AnyEvent::Fork::Serve::OWNER = $parent; |
559 | $AnyEvent::Fork::Serve::OWNER = $parent; |
445 | close $fh; |
560 | close $fh; |
446 | $0 = "$_[1] of $parent"; |
561 | $0 = "$_[1] of $parent"; |
447 | $SIG{CHLD} = 'IGNORE'; |
|
|
448 | AnyEvent::Fork::Serve::serve ($slave); |
562 | AnyEvent::Fork::Serve::serve ($slave); |
449 | exit 0; |
563 | exit 0; |
450 | } elsif (!$pid) { |
564 | } elsif (!$pid) { |
451 | die "AnyEvent::Fork::Early/Template: unable to fork template process: $!"; |
565 | die "AnyEvent::Fork::Early/Template: unable to fork template process: $!"; |
452 | } |
566 | } |
… | |
… | |
506 | |
620 | |
507 | You should use C<new> whenever possible, except when having a template |
621 | You should use C<new> whenever possible, except when having a template |
508 | process around is unacceptable. |
622 | process around is unacceptable. |
509 | |
623 | |
510 | The path to the perl interpreter is divined using various methods - first |
624 | The path to the perl interpreter is divined using various methods - first |
511 | C<$^X> is investigated to see if the path ends with something that sounds |
625 | C<$^X> is investigated to see if the path ends with something that looks |
512 | as if it were the perl interpreter. Failing this, the module falls back to |
626 | as if it were the perl interpreter. Failing this, the module falls back to |
513 | using C<$Config::Config{perlpath}>. |
627 | using C<$Config::Config{perlpath}>. |
514 | |
628 | |
|
|
629 | The path to perl can also be overriden by setting the global variable |
|
|
630 | C<$AnyEvent::Fork::PERL> - it's value will be used for all subsequent |
|
|
631 | invocations. |
|
|
632 | |
515 | =cut |
633 | =cut |
|
|
634 | |
|
|
635 | our $PERL; |
516 | |
636 | |
517 | sub new_exec { |
637 | sub new_exec { |
518 | my ($self) = @_; |
638 | my ($self) = @_; |
519 | |
639 | |
520 | return $EARLY->fork |
640 | return $EARLY->fork |
521 | if $EARLY; |
641 | if $EARLY; |
522 | |
642 | |
|
|
643 | unless (defined $PERL) { |
523 | # first find path of perl |
644 | # first find path of perl |
524 | my $perl = $; |
645 | my $perl = $^X; |
525 | |
646 | |
526 | # first we try $^X, but the path must be absolute (always on win32), and end in sth. |
647 | # first we try $^X, but the path must be absolute (always on win32), and end in sth. |
527 | # that looks like perl. this obviously only works for posix and win32 |
648 | # that looks like perl. this obviously only works for posix and win32 |
528 | unless ( |
649 | unless ( |
529 | ($^O eq "MSWin32" || $perl =~ m%^/%) |
650 | ($^O eq "MSWin32" || $perl =~ m%^/%) |
530 | && $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i |
651 | && $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i |
531 | ) { |
652 | ) { |
532 | # if it doesn't look perlish enough, try Config |
653 | # if it doesn't look perlish enough, try Config |
533 | require Config; |
654 | require Config; |
534 | $perl = $Config::Config{perlpath}; |
655 | $perl = $Config::Config{perlpath}; |
535 | $perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/; |
656 | $perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/; |
|
|
657 | } |
|
|
658 | |
|
|
659 | $PERL = $perl; |
536 | } |
660 | } |
537 | |
661 | |
538 | require Proc::FastSpawn; |
662 | require Proc::FastSpawn; |
539 | |
663 | |
540 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
664 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
… | |
… | |
548 | #local $ENV{PERL5LIB} = join ":", grep !ref, @INC; |
672 | #local $ENV{PERL5LIB} = join ":", grep !ref, @INC; |
549 | my %env = %ENV; |
673 | my %env = %ENV; |
550 | $env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC; |
674 | $env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC; |
551 | |
675 | |
552 | my $pid = Proc::FastSpawn::spawn ( |
676 | my $pid = Proc::FastSpawn::spawn ( |
553 | $perl, |
677 | $PERL, |
554 | ["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$], |
678 | [$PERL, "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$], |
555 | [map "$_=$env{$_}", keys %env], |
679 | [map "$_=$env{$_}", keys %env], |
556 | ) or die "unable to spawn AnyEvent::Fork server: $!"; |
680 | ) or die "unable to spawn AnyEvent::Fork server: $!"; |
557 | |
681 | |
558 | $self->_new ($fh, $pid) |
682 | $self->_new ($fh, $pid) |
559 | } |
683 | } |
560 | |
684 | |
561 | =item $pid = $proc->pid |
685 | =item $pid = $proc->pid |
562 | |
686 | |
563 | Returns the process id of the process I<iff it is a direct child of the |
687 | Returns the process id of the process I<iff it is a direct child of the |
564 | process running AnyEvent::Fork>, and C<undef> otherwise. |
688 | process running AnyEvent::Fork>, and C<undef> otherwise. As a general |
|
|
689 | rule (that you cannot rely upon), processes created via C<new_exec>, |
|
|
690 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template> are direct |
|
|
691 | children, while all other processes are not. |
565 | |
692 | |
566 | Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and |
693 | Or in other words, you do not normally have to take care of zombies for |
567 | L<AnyEvent::Fork::Template> are direct children, and you are responsible |
694 | processes created via C<new>, but when in doubt, or zombies are a problem, |
568 | to clean up their zombies when they die. |
695 | you need to check whether a process is a diretc child by calling this |
569 | |
696 | method, and possibly creating a child watcher or reap it manually. |
570 | All other processes are not direct children, and will be cleaned up by |
|
|
571 | AnyEvent::Fork itself. |
|
|
572 | |
697 | |
573 | =cut |
698 | =cut |
574 | |
699 | |
575 | sub pid { |
700 | sub pid { |
576 | $_[0][0] |
701 | $_[0][PID] |
577 | } |
702 | } |
578 | |
703 | |
579 | =item $proc = $proc->eval ($perlcode, @args) |
704 | =item $proc = $proc->eval ($perlcode, @args) |
580 | |
705 | |
581 | Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to |
706 | Evaluates the given C<$perlcode> as ... Perl code, while setting C<@_> to |
582 | the strings specified by C<@args>, in the "main" package. |
707 | the strings specified by C<@args>, in the "main" package. |
583 | |
708 | |
584 | This call is meant to do any custom initialisation that might be required |
709 | This call is meant to do any custom initialisation that might be required |
585 | (for example, the C<require> method uses it). It's not supposed to be used |
710 | (for example, the C<require> method uses it). It's not supposed to be used |
586 | to completely take over the process, use C<run> for that. |
711 | to completely take over the process, use C<run> for that. |
… | |
… | |
595 | C<send_xxx> methods, such as file handles. See the L<use AnyEvent::Fork as |
720 | C<send_xxx> methods, such as file handles. See the L<use AnyEvent::Fork as |
596 | a faster fork+exec> example to see it in action. |
721 | a faster fork+exec> example to see it in action. |
597 | |
722 | |
598 | Returns the process object for easy chaining of method calls. |
723 | Returns the process object for easy chaining of method calls. |
599 | |
724 | |
|
|
725 | It's common to want to call an iniitalisation function with some |
|
|
726 | arguments. Make sure you actually pass C<@_> to that function (for example |
|
|
727 | by using C<&name> syntax), and do not just specify a function name: |
|
|
728 | |
|
|
729 | $proc->eval ('&MyModule::init', $string1, $string2); |
|
|
730 | |
600 | =cut |
731 | =cut |
601 | |
732 | |
602 | sub eval { |
733 | sub eval { |
603 | my ($self, $code, @args) = @_; |
734 | my ($self, $code, @args) = @_; |
604 | |
735 | |
… | |
… | |
648 | sub send_fh { |
779 | sub send_fh { |
649 | my ($self, @fh) = @_; |
780 | my ($self, @fh) = @_; |
650 | |
781 | |
651 | for my $fh (@fh) { |
782 | for my $fh (@fh) { |
652 | $self->_cmd ("h"); |
783 | $self->_cmd ("h"); |
653 | push @{ $self->[2] }, \$fh; |
784 | push @{ $self->[QUEUE] }, \$fh; |
654 | } |
785 | } |
655 | |
786 | |
656 | $self |
787 | $self |
657 | } |
788 | } |
658 | |
789 | |
… | |
… | |
707 | |
838 | |
708 | Even if not used otherwise, the socket can be a good indicator for the |
839 | Even if not used otherwise, the socket can be a good indicator for the |
709 | existence of the process - if the other process exits, you get a readable |
840 | existence of the process - if the other process exits, you get a readable |
710 | event on it, because exiting the process closes the socket (if it didn't |
841 | event on it, because exiting the process closes the socket (if it didn't |
711 | create any children using fork). |
842 | create any children using fork). |
|
|
843 | |
|
|
844 | =over 4 |
|
|
845 | |
|
|
846 | =item Compatibility to L<AnyEvent::Fork::Remote> |
|
|
847 | |
|
|
848 | If you want to write code that works with both this module and |
|
|
849 | L<AnyEvent::Fork::Remote>, you need to write your code so that it assumes |
|
|
850 | there are two file handles for communications, which might not be unix |
|
|
851 | domain sockets. The C<run> function should start like this: |
|
|
852 | |
|
|
853 | sub run { |
|
|
854 | my ($rfh, @args) = @_; # @args is your normal arguments |
|
|
855 | my $wfh = fileno $rfh ? $rfh : *STDOUT; |
|
|
856 | |
|
|
857 | # now use $rfh for reading and $wfh for writing |
|
|
858 | } |
|
|
859 | |
|
|
860 | This checks whether the passed file handle is, in fact, the process |
|
|
861 | C<STDIN> handle. If it is, then the function was invoked visa |
|
|
862 | L<AnyEvent::Fork::Remote>, so STDIN should be used for reading and |
|
|
863 | C<STDOUT> should be used for writing. |
|
|
864 | |
|
|
865 | In all other cases, the function was called via this module, and there is |
|
|
866 | only one file handle that should be sued for reading and writing. |
|
|
867 | |
|
|
868 | =back |
712 | |
869 | |
713 | Example: create a template for a process pool, pass a few strings, some |
870 | Example: create a template for a process pool, pass a few strings, some |
714 | file handles, then fork, pass one more string, and run some code. |
871 | file handles, then fork, pass one more string, and run some code. |
715 | |
872 | |
716 | my $pool = AnyEvent::Fork |
873 | my $pool = AnyEvent::Fork |
… | |
… | |
744 | =cut |
901 | =cut |
745 | |
902 | |
746 | sub run { |
903 | sub run { |
747 | my ($self, $func, $cb) = @_; |
904 | my ($self, $func, $cb) = @_; |
748 | |
905 | |
749 | $self->[4] = $cb; |
906 | $self->[CB] = $cb; |
750 | $self->_cmd (r => $func); |
907 | $self->_cmd (r => $func); |
|
|
908 | } |
|
|
909 | |
|
|
910 | =back |
|
|
911 | |
|
|
912 | =head2 EXPERIMENTAL METHODS |
|
|
913 | |
|
|
914 | These methods might go away completely or change behaviour, at any time. |
|
|
915 | |
|
|
916 | =over 4 |
|
|
917 | |
|
|
918 | =item $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
919 | |
|
|
920 | Flushes all commands out to the process and then calls the callback with |
|
|
921 | the communications socket. |
|
|
922 | |
|
|
923 | The process object becomes unusable on return from this function - any |
|
|
924 | further method calls result in undefined behaviour. |
|
|
925 | |
|
|
926 | The point of this method is to give you a file handle that you can pass |
|
|
927 | to another process. In that other process, you can call C<new_from_fh |
|
|
928 | AnyEvent::Fork $fh> to create a new C<AnyEvent::Fork> object from it, |
|
|
929 | thereby effectively passing a fork object to another process. |
|
|
930 | |
|
|
931 | =cut |
|
|
932 | |
|
|
933 | sub to_fh { |
|
|
934 | my ($self, $cb) = @_; |
|
|
935 | |
|
|
936 | $self->[CB] = $cb; |
|
|
937 | |
|
|
938 | unless ($self->[WW]) { |
|
|
939 | $self->[CB]->($self->[FH]); |
|
|
940 | @$self = (); |
|
|
941 | } |
|
|
942 | } |
|
|
943 | |
|
|
944 | =item new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
945 | |
|
|
946 | Takes a file handle originally rceeived by the C<to_fh> method and creates |
|
|
947 | a new C<AnyEvent:Fork> object. The child process itself will not change in |
|
|
948 | any way, i.e. it will keep all the modifications done to it before calling |
|
|
949 | C<to_fh>. |
|
|
950 | |
|
|
951 | The new object is very much like the original object, except that the |
|
|
952 | C<pid> method will return C<undef> even if the process is a direct child. |
|
|
953 | |
|
|
954 | =cut |
|
|
955 | |
|
|
956 | sub new_from_fh { |
|
|
957 | my ($class, $fh) = @_; |
|
|
958 | |
|
|
959 | $class->_new ($fh) |
751 | } |
960 | } |
752 | |
961 | |
753 | =back |
962 | =back |
754 | |
963 | |
755 | =head1 PERFORMANCE |
964 | =head1 PERFORMANCE |
… | |
… | |
765 | |
974 | |
766 | 2079 new processes per second, using manual socketpair + fork |
975 | 2079 new processes per second, using manual socketpair + fork |
767 | |
976 | |
768 | Then I did the same thing, but instead of calling fork, I called |
977 | Then I did the same thing, but instead of calling fork, I called |
769 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
978 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
770 | socket form the child to close on exit. This does the same thing as manual |
979 | socket from the child to close on exit. This does the same thing as manual |
771 | socket pair + fork, except that what is forked is the template process |
980 | socket pair + fork, except that what is forked is the template process |
772 | (2440kB), and the socket needs to be passed to the server at the other end |
981 | (2440kB), and the socket needs to be passed to the server at the other end |
773 | of the socket first. |
982 | of the socket first. |
774 | |
983 | |
775 | 2307 new processes per second, using AnyEvent::Fork->new |
984 | 2307 new processes per second, using AnyEvent::Fork->new |
… | |
… | |
782 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
991 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
783 | though it uses the same operations, but adds a lot of overhead? |
992 | though it uses the same operations, but adds a lot of overhead? |
784 | |
993 | |
785 | The difference is simply the process size: forking the 5MB process takes |
994 | The difference is simply the process size: forking the 5MB process takes |
786 | so much longer than forking the 2.5MB template process that the extra |
995 | so much longer than forking the 2.5MB template process that the extra |
787 | overhead introduced is canceled out. |
996 | overhead is canceled out. |
788 | |
997 | |
789 | If the benchmark process grows, the normal fork becomes even slower: |
998 | If the benchmark process grows, the normal fork becomes even slower: |
790 | |
999 | |
791 | 1340 new processes, manual fork of a 20MB process |
1000 | 1340 new processes, manual fork of a 20MB process |
792 | 731 new processes, manual fork of a 200MB process |
1001 | 731 new processes, manual fork of a 200MB process |
… | |
… | |
851 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay |
1060 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay |
852 | initialising them, for example, by calling C<init Gtk2> manually. |
1061 | initialising them, for example, by calling C<init Gtk2> manually. |
853 | |
1062 | |
854 | =item exiting calls object destructors |
1063 | =item exiting calls object destructors |
855 | |
1064 | |
856 | This only applies to users of Lc<AnyEvent::Fork:Early> and |
1065 | This only applies to users of L<AnyEvent::Fork:Early> and |
857 | L<AnyEvent::Fork::Template>. |
1066 | L<AnyEvent::Fork::Template>, or when initialising code creates objects |
|
|
1067 | that reference external resources. |
858 | |
1068 | |
859 | When a process created by AnyEvent::Fork exits, it might do so by calling |
1069 | When a process created by AnyEvent::Fork exits, it might do so by calling |
860 | exit, or simply letting perl reach the end of the program. At which point |
1070 | exit, or simply letting perl reach the end of the program. At which point |
861 | Perl runs all destructors. |
1071 | Perl runs all destructors. |
862 | |
1072 | |
… | |
… | |
881 | to make it so, mostly due to the bloody broken perl that nobody seems to |
1091 | to make it so, mostly due to the bloody broken perl that nobody seems to |
882 | care about. The fork emulation is a bad joke - I have yet to see something |
1092 | care about. The fork emulation is a bad joke - I have yet to see something |
883 | useful that you can do with it without running into memory corruption |
1093 | useful that you can do with it without running into memory corruption |
884 | issues or other braindamage. Hrrrr. |
1094 | issues or other braindamage. Hrrrr. |
885 | |
1095 | |
|
|
1096 | Since fork is endlessly broken on win32 perls (it doesn't even remotely |
|
|
1097 | work within it's documented limits) and quite obviously it's not getting |
|
|
1098 | improved any time soon, the best way to proceed on windows would be to |
|
|
1099 | always use C<new_exec> and thus never rely on perl's fork "emulation". |
|
|
1100 | |
886 | Cygwin perl is not supported at the moment due to some hilarious |
1101 | Cygwin perl is not supported at the moment due to some hilarious |
887 | shortcomings of its API - see L<IO::FDPoll> for more details. |
1102 | shortcomings of its API - see L<IO::FDPoll> for more details. If you never |
|
|
1103 | use C<send_fh> and always use C<new_exec> to create processes, it should |
|
|
1104 | work though. |
|
|
1105 | |
|
|
1106 | =head1 USING AnyEvent::Fork IN SUBPROCESSES |
|
|
1107 | |
|
|
1108 | AnyEvent::Fork itself cannot generally be used in subprocesses. As long as |
|
|
1109 | only one process ever forks new processes, sharing the template processes |
|
|
1110 | is possible (you could use a pipe as a lock by writing a byte into it to |
|
|
1111 | unlock, and reading the byte to lock for example) |
|
|
1112 | |
|
|
1113 | To make concurrent calls possible after fork, you should get rid of the |
|
|
1114 | template and early fork processes. AnyEvent::Fork will create a new |
|
|
1115 | template process as needed. |
|
|
1116 | |
|
|
1117 | undef $AnyEvent::Fork::EARLY; |
|
|
1118 | undef $AnyEvent::Fork::TEMPLATE; |
|
|
1119 | |
|
|
1120 | It doesn't matter whether you get rid of them in the parent or child after |
|
|
1121 | a fork. |
888 | |
1122 | |
889 | =head1 SEE ALSO |
1123 | =head1 SEE ALSO |
890 | |
1124 | |
891 | L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter), |
1125 | L<AnyEvent::Fork::Early>, to avoid executing a perl interpreter at all |
|
|
1126 | (part of this distribution). |
|
|
1127 | |
892 | L<AnyEvent::Fork::Template> (to create a process by forking the main |
1128 | L<AnyEvent::Fork::Template>, to create a process by forking the main |
893 | program at a convenient time). |
1129 | program at a convenient time (part of this distribution). |
894 | |
1130 | |
895 | =head1 AUTHOR |
1131 | L<AnyEvent::Fork::Remote>, for another way to create processes that is |
|
|
1132 | mostly compatible to this module and modules building on top of it, but |
|
|
1133 | works better with remote processes. |
|
|
1134 | |
|
|
1135 | L<AnyEvent::Fork::RPC>, for simple RPC to child processes (on CPAN). |
|
|
1136 | |
|
|
1137 | L<AnyEvent::Fork::Pool>, for simple worker process pool (on CPAN). |
|
|
1138 | |
|
|
1139 | =head1 AUTHOR AND CONTACT INFORMATION |
896 | |
1140 | |
897 | Marc Lehmann <schmorp@schmorp.de> |
1141 | Marc Lehmann <schmorp@schmorp.de> |
898 | http://home.schmorp.de/ |
1142 | http://software.schmorp.de/pkg/AnyEvent-Fork |
899 | |
1143 | |
900 | =cut |
1144 | =cut |
901 | |
1145 | |
902 | 1 |
1146 | 1 |
903 | |
1147 | |