… | |
… | |
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, |
42 | |
43 | and so on. |
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 | |
|
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70 | =head2 PROBLEM STATEMENT |
|
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71 | |
|
|
72 | There are two traditional ways to implement parallel processing on UNIX |
|
|
73 | like operating systems - fork and process, and fork+exec and process. They |
|
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74 | have different advantages and disadvantages that I describe below, |
|
|
75 | together with how this module tries to mitigate the disadvantages. |
|
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76 | |
|
|
77 | =over 4 |
|
|
78 | |
|
|
79 | =item Forking from a big process can be very slow. |
|
|
80 | |
|
|
81 | A 5GB process needs 0.05s to fork on my 3.6GHz amd64 GNU/Linux box. This |
|
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82 | overhead is often shared with exec (because you have to fork first), but |
|
|
83 | in some circumstances (e.g. when vfork is used), fork+exec can be much |
|
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84 | faster. |
|
|
85 | |
|
|
86 | This module can help here by telling a small(er) helper process to fork, |
|
|
87 | which is faster then forking the main process, and also uses vfork where |
|
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88 | possible. This gives the speed of vfork, with the flexibility of fork. |
|
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89 | |
|
|
90 | =item Forking usually creates a copy-on-write copy of the parent |
|
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91 | process. |
|
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92 | |
|
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93 | For example, modules or data files that are loaded will not use additional |
|
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94 | memory after a fork. Exec'ing a new process, in contrast, means modules |
|
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95 | and data files might need to be loaded again, at extra CPU and memory |
|
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96 | cost. |
|
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97 | |
|
|
98 | But when forking, you still create a copy of your data structures - if |
|
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99 | the program frees them and replaces them by new data, the child processes |
|
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100 | will retain the old version even if it isn't used, which can suddenly and |
|
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101 | unexpectedly increase memory usage when freeing memory. |
|
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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 | |
|
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112 | There is a trade-off between more sharing with fork (which can be good or |
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113 | bad), and no sharing with exec. |
|
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114 | |
|
|
115 | This module allows the main program to do a controlled fork, and allows |
|
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116 | modules to exec processes safely at any time. When creating a custom |
|
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117 | process pool you can take advantage of data sharing via fork without |
|
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118 | risking to share large dynamic data structures that will blow up child |
|
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119 | memory usage. |
|
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120 | |
|
|
121 | In other words, this module puts you into control over what is being |
|
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122 | shared and what isn't, at all times. |
|
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123 | |
|
|
124 | =item Exec'ing a new perl process might be difficult. |
|
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125 | |
|
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126 | For example, it is not easy to find the correct path to the perl |
|
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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. |
|
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129 | |
|
|
130 | This module tries hard to identify the correct path to the perl |
|
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131 | interpreter. With a cooperative main program, exec'ing the interpreter |
|
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132 | might not even be necessary, but even without help from the main program, |
|
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133 | it will still work when used from a module. |
|
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134 | |
|
|
135 | =item Exec'ing a new perl process might be slow, as all necessary modules |
|
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136 | have to be loaded from disk again, with no guarantees of success. |
|
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137 | |
|
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138 | Long running processes might run into problems when perl is upgraded |
|
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139 | and modules are no longer loadable because they refer to a different |
|
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140 | perl version, or parts of a distribution are newer than the ones already |
|
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141 | loaded. |
|
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142 | |
|
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143 | This module supports creating pre-initialised perl processes to be used as |
|
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144 | a template for new processes at a later time, e.g. for use in a process |
|
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145 | pool. |
|
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146 | |
|
|
147 | =item Forking might be impossible when a program is running. |
|
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148 | |
|
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149 | For example, POSIX makes it almost impossible to fork from a |
|
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150 | multi-threaded program while doing anything useful in the child - in |
|
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151 | fact, if your perl program uses POSIX threads (even indirectly via |
|
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152 | e.g. L<IO::AIO> or L<threads>), you cannot call fork on the perl level |
|
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153 | anymore without risking memory corruption or worse on a number of |
|
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154 | operating systems. |
|
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155 | |
|
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156 | This module can safely fork helper processes at any time, by calling |
|
|
157 | fork+exec in C, in a POSIX-compatible way (via L<Proc::FastSpawn>). |
|
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158 | |
|
|
159 | =item Parallel processing with fork might be inconvenient or difficult |
|
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160 | to implement. Modules might not work in both parent and child. |
|
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161 | |
|
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162 | For example, when a program uses an event loop and creates watchers it |
|
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163 | becomes very hard to use the event loop from a child program, as the |
|
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164 | watchers already exist but are only meaningful in the parent. Worse, a |
|
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165 | module might want to use such a module, not knowing whether another module |
|
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166 | or the main program also does, leading to problems. |
|
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167 | |
|
|
168 | Apart from event loops, graphical toolkits also commonly fall into the |
|
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169 | "unsafe module" category, or just about anything that communicates with |
|
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170 | the external world, such as network libraries and file I/O modules, which |
|
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171 | usually don't like being copied and then allowed to continue in two |
|
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172 | processes. |
|
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173 | |
|
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174 | With this module only the main program is allowed to create new processes |
|
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175 | by forking (because only the main program can know when it is still safe |
|
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176 | to do so) - all other processes are created via fork+exec, which makes it |
|
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177 | possible to use modules such as event loops or window interfaces safely. |
|
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178 | |
|
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179 | =back |
44 | |
180 | |
45 | =head1 EXAMPLES |
181 | =head1 EXAMPLES |
|
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182 | |
|
|
183 | This is where the wall of text ends and code speaks. |
46 | |
184 | |
47 | =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. |
48 | |
186 | |
49 | AnyEvent::Fork |
187 | AnyEvent::Fork |
50 | ->new |
188 | ->new |
… | |
… | |
54 | |
192 | |
55 | # now $master_filehandle is connected to the |
193 | # now $master_filehandle is connected to the |
56 | # $slave_filehandle in the new process. |
194 | # $slave_filehandle in the new process. |
57 | }); |
195 | }); |
58 | |
196 | |
59 | # MyModule::worker might look like this |
197 | C<MyModule> might look like this: |
|
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198 | |
|
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199 | package MyModule; |
|
|
200 | |
60 | sub MyModule::worker { |
201 | sub worker { |
61 | my ($slave_filehandle) = @_; |
202 | my ($slave_filehandle) = @_; |
62 | |
203 | |
63 | # now $slave_filehandle is connected to the $master_filehandle |
204 | # now $slave_filehandle is connected to the $master_filehandle |
64 | # in the original prorcess. have fun! |
205 | # in the original process. have fun! |
65 | } |
206 | } |
66 | |
207 | |
67 | =head2 Create a pool of server processes all accepting on the same socket. |
208 | =head2 Create a pool of server processes all accepting on the same socket. |
68 | |
209 | |
69 | # create listener socket |
210 | # create listener socket |
… | |
… | |
84 | } |
225 | } |
85 | |
226 | |
86 | # now do other things - maybe use the filehandle provided by run |
227 | # now do other things - maybe use the filehandle provided by run |
87 | # to wait for the processes to die. or whatever. |
228 | # to wait for the processes to die. or whatever. |
88 | |
229 | |
89 | # My::Server::run might look like this |
230 | C<My::Server> might look like this: |
90 | sub My::Server::run { |
231 | |
|
|
232 | package My::Server; |
|
|
233 | |
|
|
234 | sub run { |
91 | my ($slave, $listener, $id) = @_; |
235 | my ($slave, $listener, $id) = @_; |
92 | |
236 | |
93 | close $slave; # we do not use the socket, so close it to save resources |
237 | close $slave; # we do not use the socket, so close it to save resources |
94 | |
238 | |
95 | # we could go ballistic and use e.g. AnyEvent here, or IO::AIO, |
239 | # we could go ballistic and use e.g. AnyEvent here, or IO::AIO, |
… | |
… | |
99 | } |
243 | } |
100 | } |
244 | } |
101 | |
245 | |
102 | =head2 use AnyEvent::Fork as a faster fork+exec |
246 | =head2 use AnyEvent::Fork as a faster fork+exec |
103 | |
247 | |
104 | This runs /bin/echo hi, with stdout redirected to /tmp/log and stderr to |
248 | This runs C</bin/echo hi>, with standard output redirected to F</tmp/log> |
105 | the communications socket. It is usually faster than fork+exec, but still |
249 | and standard error redirected to the communications socket. It is usually |
106 | let's you prepare the environment. |
250 | faster than fork+exec, but still lets you prepare the environment. |
107 | |
251 | |
108 | open my $output, ">/tmp/log" or die "$!"; |
252 | open my $output, ">/tmp/log" or die "$!"; |
109 | |
253 | |
110 | AnyEvent::Fork |
254 | AnyEvent::Fork |
111 | ->new |
255 | ->new |
112 | ->eval (' |
256 | ->eval (' |
|
|
257 | # compile a helper function for later use |
113 | sub run { |
258 | sub run { |
114 | my ($fh, $output, @cmd) = @_; |
259 | my ($fh, $output, @cmd) = @_; |
115 | |
260 | |
116 | # perl will clear close-on-exec on STDOUT/STDERR |
261 | # perl will clear close-on-exec on STDOUT/STDERR |
117 | open STDOUT, ">&", $output or die; |
262 | open STDOUT, ">&", $output or die; |
… | |
… | |
124 | ->send_arg ("/bin/echo", "hi") |
269 | ->send_arg ("/bin/echo", "hi") |
125 | ->run ("run", my $cv = AE::cv); |
270 | ->run ("run", my $cv = AE::cv); |
126 | |
271 | |
127 | my $stderr = $cv->recv; |
272 | my $stderr = $cv->recv; |
128 | |
273 | |
129 | =head1 PROBLEM STATEMENT |
274 | =head2 For stingy users: put the worker code into a C<DATA> section. |
130 | |
275 | |
131 | There are two ways to implement parallel processing on UNIX like operating |
276 | When you want to be stingy with files, you can put your code into the |
132 | systems - fork and process, and fork+exec and process. They have different |
277 | C<DATA> section of your module (or program): |
133 | advantages and disadvantages that I describe below, together with how this |
|
|
134 | module tries to mitigate the disadvantages. |
|
|
135 | |
278 | |
136 | =over 4 |
279 | use AnyEvent::Fork; |
137 | |
280 | |
138 | =item Forking from a big process can be very slow (a 5GB process needs |
281 | AnyEvent::Fork |
139 | 0.05s to fork on my 3.6GHz amd64 GNU/Linux box for example). This overhead |
282 | ->new |
140 | is often shared with exec (because you have to fork first), but in some |
283 | ->eval (do { local $/; <DATA> }) |
141 | circumstances (e.g. when vfork is used), fork+exec can be much faster. |
284 | ->run ("doit", sub { ... }); |
142 | |
285 | |
143 | This module can help here by telling a small(er) helper process to fork, |
286 | __DATA__ |
144 | or fork+exec instead. |
|
|
145 | |
287 | |
146 | =item Forking usually creates a copy-on-write copy of the parent |
288 | sub doit { |
147 | process. Memory (for example, modules or data files that have been |
289 | ... do something! |
148 | will not take additional memory). When exec'ing a new process, modules |
290 | } |
149 | and data files might need to be loaded again, at extra CPU and memory |
|
|
150 | cost. Likewise when forking, all data structures are copied as well - if |
|
|
151 | the program frees them and replaces them by new data, the child processes |
|
|
152 | will retain the memory even if it isn't used. |
|
|
153 | |
291 | |
154 | This module allows the main program to do a controlled fork, and allows |
292 | =head2 For stingy standalone programs: do not rely on external files at |
155 | modules to exec processes safely at any time. When creating a custom |
293 | all. |
156 | process pool you can take advantage of data sharing via fork without |
|
|
157 | risking to share large dynamic data structures that will blow up child |
|
|
158 | memory usage. |
|
|
159 | |
294 | |
160 | =item Exec'ing a new perl process might be difficult and slow. For |
295 | For single-file scripts it can be inconvenient to rely on external |
161 | example, it is not easy to find the correct path to the perl interpreter, |
296 | files - even when using a C<DATA> section, you still need to C<exec> an |
162 | and all modules have to be loaded from disk again. Long running processes |
297 | external perl interpreter, which might not be available when using |
163 | might run into problems when perl is upgraded for example. |
298 | L<App::Staticperl>, L<Urlader> or L<PAR::Packer> for example. |
164 | |
299 | |
165 | This module supports creating pre-initialised perl processes to be used |
300 | Two modules help here - L<AnyEvent::Fork::Early> forks a template process |
166 | as template, and also tries hard to identify the correct path to the perl |
301 | for all further calls to C<new_exec>, and L<AnyEvent::Fork::Template> |
167 | interpreter. With a cooperative main program, exec'ing the interpreter |
302 | forks the main program as a template process. |
168 | might not even be necessary. |
|
|
169 | |
303 | |
170 | =item Forking might be impossible when a program is running. For example, |
304 | Here is how your main program should look like: |
171 | POSIX makes it almost impossible to fork from a multi-threaded program and |
|
|
172 | do anything useful in the child - strictly speaking, if your perl program |
|
|
173 | uses posix threads (even indirectly via e.g. L<IO::AIO> or L<threads>), |
|
|
174 | you cannot call fork on the perl level anymore, at all. |
|
|
175 | |
305 | |
176 | This module can safely fork helper processes at any time, by calling |
306 | #! perl |
177 | fork+exec in C, in a POSIX-compatible way. |
|
|
178 | |
307 | |
179 | =item Parallel processing with fork might be inconvenient or difficult |
308 | # optional, as the very first thing. |
180 | to implement. For example, when a program uses an event loop and creates |
309 | # in case modules want to create their own processes. |
181 | watchers it becomes very hard to use the event loop from a child |
310 | use AnyEvent::Fork::Early; |
182 | program, as the watchers already exist but are only meaningful in the |
|
|
183 | parent. Worse, a module might want to use such a system, not knowing |
|
|
184 | whether another module or the main program also does, leading to problems. |
|
|
185 | |
311 | |
186 | This module only lets the main program create pools by forking (because |
312 | # next, load all modules you need in your template process |
187 | only the main program can know when it is still safe to do so) - all other |
313 | use Example::My::Module |
188 | pools are created by fork+exec, after which such modules can again be |
314 | use Example::Whatever; |
189 | loaded. |
|
|
190 | |
315 | |
191 | =back |
316 | # next, put your run function definition and anything else you |
|
|
317 | # need, but do not use code outside of BEGIN blocks. |
|
|
318 | sub worker_run { |
|
|
319 | my ($fh, @args) = @_; |
|
|
320 | ... |
|
|
321 | } |
|
|
322 | |
|
|
323 | # now preserve everything so far as AnyEvent::Fork object |
|
|
324 | # in $TEMPLATE. |
|
|
325 | use AnyEvent::Fork::Template; |
|
|
326 | |
|
|
327 | # do not put code outside of BEGIN blocks until here |
|
|
328 | |
|
|
329 | # now use the $TEMPLATE process in any way you like |
|
|
330 | |
|
|
331 | # for example: create 10 worker processes |
|
|
332 | my @worker; |
|
|
333 | my $cv = AE::cv; |
|
|
334 | for (1..10) { |
|
|
335 | $cv->begin; |
|
|
336 | $TEMPLATE->fork->send_arg ($_)->run ("worker_run", sub { |
|
|
337 | push @worker, shift; |
|
|
338 | $cv->end; |
|
|
339 | }); |
|
|
340 | } |
|
|
341 | $cv->recv; |
192 | |
342 | |
193 | =head1 CONCEPTS |
343 | =head1 CONCEPTS |
194 | |
344 | |
195 | This module can create new processes either by executing a new perl |
345 | This module can create new processes either by executing a new perl |
196 | process, or by forking from an existing "template" process. |
346 | process, or by forking from an existing "template" process. |
|
|
347 | |
|
|
348 | All these processes are called "child processes" (whether they are direct |
|
|
349 | children or not), while the process that manages them is called the |
|
|
350 | "parent process". |
197 | |
351 | |
198 | Each such process comes with its own file handle that can be used to |
352 | Each such process comes with its own file handle that can be used to |
199 | communicate with it (it's actually a socket - one end in the new process, |
353 | communicate with it (it's actually a socket - one end in the new process, |
200 | one end in the main process), and among the things you can do in it are |
354 | one end in the main process), and among the things you can do in it are |
201 | load modules, fork new processes, send file handles to it, and execute |
355 | load modules, fork new processes, send file handles to it, and execute |
… | |
… | |
275 | my ($fork_fh) = @_; |
429 | my ($fork_fh) = @_; |
276 | }); |
430 | }); |
277 | |
431 | |
278 | =back |
432 | =back |
279 | |
433 | |
280 | =head1 FUNCTIONS |
434 | =head1 THE C<AnyEvent::Fork> CLASS |
|
|
435 | |
|
|
436 | This module exports nothing, and only implements a single class - |
|
|
437 | C<AnyEvent::Fork>. |
|
|
438 | |
|
|
439 | There are two class constructors that both create new processes - C<new> |
|
|
440 | and C<new_exec>. The C<fork> method creates a new process by forking an |
|
|
441 | existing one and could be considered a third constructor. |
|
|
442 | |
|
|
443 | Most of the remaining methods deal with preparing the new process, by |
|
|
444 | loading code, evaluating code and sending data to the new process. They |
|
|
445 | usually return the process object, so you can chain method calls. |
|
|
446 | |
|
|
447 | If a process object is destroyed before calling its C<run> method, then |
|
|
448 | the process simply exits. After C<run> is called, all responsibility is |
|
|
449 | passed to the specified function. |
|
|
450 | |
|
|
451 | As long as there is any outstanding work to be done, process objects |
|
|
452 | resist being destroyed, so there is no reason to store them unless you |
|
|
453 | need them later - configure and forget works just fine. |
281 | |
454 | |
282 | =over 4 |
455 | =over 4 |
283 | |
456 | |
284 | =cut |
457 | =cut |
285 | |
458 | |
… | |
… | |
292 | use AnyEvent; |
465 | use AnyEvent; |
293 | use AnyEvent::Util (); |
466 | use AnyEvent::Util (); |
294 | |
467 | |
295 | use IO::FDPass; |
468 | use IO::FDPass; |
296 | |
469 | |
297 | our $VERSION = 0.5; |
470 | our $VERSION = 1.31; |
298 | |
|
|
299 | our $PERL; # the path to the perl interpreter, deduces with various forms of magic |
|
|
300 | |
|
|
301 | =item my $pool = new AnyEvent::Fork key => value... |
|
|
302 | |
|
|
303 | Create a new process pool. The following named parameters are supported: |
|
|
304 | |
|
|
305 | =over 4 |
|
|
306 | |
|
|
307 | =back |
|
|
308 | |
|
|
309 | =cut |
|
|
310 | |
471 | |
311 | # the early fork template process |
472 | # the early fork template process |
312 | our $EARLY; |
473 | our $EARLY; |
313 | |
474 | |
314 | # the empty template process |
475 | # the empty template process |
315 | 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; |
|
|
488 | |
|
|
489 | $self = bless [ |
|
|
490 | [], # write queue - strings or fd's |
|
|
491 | $fh, |
|
|
492 | undef, # AE watcher |
|
|
493 | $pid, |
|
|
494 | ], $self; |
|
|
495 | |
|
|
496 | $self |
|
|
497 | } |
316 | |
498 | |
317 | sub _cmd { |
499 | sub _cmd { |
318 | my $self = shift; |
500 | my $self = shift; |
319 | |
501 | |
320 | # 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 |
321 | # 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 |
322 | # it. |
504 | # it. |
323 | push @{ $self->[2] }, pack "a L/a*", $_[0], $_[1]; |
505 | push @{ $self->[QUEUE] }, pack "a L/a*", $_[0], $_[1]; |
324 | |
506 | |
325 | $self->[3] ||= AE::io $self->[1], 1, sub { |
507 | $self->[WW] ||= AE::io $self->[FH], 1, sub { |
326 | do { |
508 | do { |
327 | # 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, |
328 | # or a plain string. |
510 | # or a plain string. |
329 | |
511 | |
330 | if (ref $self->[2][0]) { |
512 | if (ref $self->[QUEUE][0]) { |
331 | # send fh |
513 | # send fh |
332 | unless (IO::FDPass::send fileno $self->[1], fileno ${ $self->[2][0] }) { |
514 | unless (IO::FDPass::send fileno $self->[FH], fileno ${ $self->[QUEUE][0] }) { |
333 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
515 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
334 | undef $self->[3]; |
516 | undef $self->[WW]; |
335 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
517 | die "AnyEvent::Fork: file descriptor send failure: $!"; |
336 | } |
518 | } |
337 | |
519 | |
338 | shift @{ $self->[2] }; |
520 | shift @{ $self->[QUEUE] }; |
339 | |
521 | |
340 | } else { |
522 | } else { |
341 | # send string |
523 | # send string |
342 | my $len = syswrite $self->[1], $self->[2][0]; |
524 | my $len = syswrite $self->[FH], $self->[QUEUE][0]; |
343 | |
525 | |
344 | unless ($len) { |
526 | unless ($len) { |
345 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
527 | return if $! == Errno::EAGAIN || $! == Errno::EWOULDBLOCK; |
346 | undef $self->[3]; |
528 | undef $self->[WW]; |
347 | die "AnyEvent::Fork: command write failure: $!"; |
529 | die "AnyEvent::Fork: command write failure: $!"; |
348 | } |
530 | } |
349 | |
531 | |
350 | substr $self->[2][0], 0, $len, ""; |
532 | substr $self->[QUEUE][0], 0, $len, ""; |
351 | shift @{ $self->[2] } unless length $self->[2][0]; |
533 | shift @{ $self->[QUEUE] } unless length $self->[QUEUE][0]; |
352 | } |
534 | } |
353 | } while @{ $self->[2] }; |
535 | } while @{ $self->[QUEUE] }; |
354 | |
536 | |
355 | # everything written |
537 | # everything written |
356 | undef $self->[3]; |
538 | undef $self->[WW]; |
357 | |
539 | |
358 | # invoke run callback, if any |
540 | # invoke run callback, if any |
359 | $self->[4]->($self->[1]) if $self->[4]; |
541 | if ($self->[CB]) { |
|
|
542 | $self->[CB]->($self->[FH]); |
|
|
543 | @$self = (); |
|
|
544 | } |
360 | }; |
545 | }; |
361 | |
546 | |
362 | () # make sure we don't leak the watcher |
547 | () # make sure we don't leak the watcher |
363 | } |
|
|
364 | |
|
|
365 | sub _new { |
|
|
366 | my ($self, $fh, $pid) = @_; |
|
|
367 | |
|
|
368 | AnyEvent::Util::fh_nonblocking $fh, 1; |
|
|
369 | |
|
|
370 | $self = bless [ |
|
|
371 | $pid, |
|
|
372 | $fh, |
|
|
373 | [], # write queue - strings or fd's |
|
|
374 | undef, # AE watcher |
|
|
375 | ], $self; |
|
|
376 | |
|
|
377 | $self |
|
|
378 | } |
548 | } |
379 | |
549 | |
380 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
550 | # fork template from current process, used by AnyEvent::Fork::Early/Template |
381 | sub _new_fork { |
551 | sub _new_fork { |
382 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
552 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
… | |
… | |
386 | |
556 | |
387 | if ($pid eq 0) { |
557 | if ($pid eq 0) { |
388 | require AnyEvent::Fork::Serve; |
558 | require AnyEvent::Fork::Serve; |
389 | $AnyEvent::Fork::Serve::OWNER = $parent; |
559 | $AnyEvent::Fork::Serve::OWNER = $parent; |
390 | close $fh; |
560 | close $fh; |
391 | $0 = "$_[1] of $parent"; |
561 | $0 = "$parent AnyEvent::Fork/exec"; |
392 | $SIG{CHLD} = 'IGNORE'; |
|
|
393 | AnyEvent::Fork::Serve::serve ($slave); |
562 | AnyEvent::Fork::Serve::serve ($slave); |
394 | exit 0; |
563 | exit 0; |
395 | } elsif (!$pid) { |
564 | } elsif (!$pid) { |
396 | die "AnyEvent::Fork::Early/Template: unable to fork template process: $!"; |
565 | die "AnyEvent::Fork::Early/Template: unable to fork template process: $!"; |
397 | } |
566 | } |
… | |
… | |
404 | Create a new "empty" perl interpreter process and returns its process |
573 | Create a new "empty" perl interpreter process and returns its process |
405 | object for further manipulation. |
574 | object for further manipulation. |
406 | |
575 | |
407 | The new process is forked from a template process that is kept around |
576 | The new process is forked from a template process that is kept around |
408 | for this purpose. When it doesn't exist yet, it is created by a call to |
577 | for this purpose. When it doesn't exist yet, it is created by a call to |
409 | C<new_exec> and kept around for future calls. |
578 | C<new_exec> first and then stays around for future calls. |
410 | |
|
|
411 | When the process object is destroyed, it will release the file handle |
|
|
412 | that connects it with the new process. When the new process has not yet |
|
|
413 | called C<run>, then the process will exit. Otherwise, what happens depends |
|
|
414 | entirely on the code that is executed. |
|
|
415 | |
579 | |
416 | =cut |
580 | =cut |
417 | |
581 | |
418 | sub new { |
582 | sub new { |
419 | my $class = shift; |
583 | my $class = shift; |
… | |
… | |
456 | |
620 | |
457 | You should use C<new> whenever possible, except when having a template |
621 | You should use C<new> whenever possible, except when having a template |
458 | process around is unacceptable. |
622 | process around is unacceptable. |
459 | |
623 | |
460 | The path to the perl interpreter is divined using various methods - first |
624 | The path to the perl interpreter is divined using various methods - first |
461 | C<$^X> is investigated to see if the path ends with something that sounds |
625 | C<$^X> is investigated to see if the path ends with something that looks |
462 | as if it were the perl interpreter. Failing this, the module falls back to |
626 | as if it were the perl interpreter. Failing this, the module falls back to |
463 | using C<$Config::Config{perlpath}>. |
627 | using C<$Config::Config{perlpath}>. |
464 | |
628 | |
|
|
629 | The path to perl can also be overridden by setting the global variable |
|
|
630 | C<$AnyEvent::Fork::PERL> - it's value will be used for all subsequent |
|
|
631 | invocations. |
|
|
632 | |
465 | =cut |
633 | =cut |
|
|
634 | |
|
|
635 | our $PERL; |
466 | |
636 | |
467 | sub new_exec { |
637 | sub new_exec { |
468 | my ($self) = @_; |
638 | my ($self) = @_; |
469 | |
639 | |
470 | return $EARLY->fork |
640 | return $EARLY->fork |
471 | if $EARLY; |
641 | if $EARLY; |
472 | |
642 | |
|
|
643 | unless (defined $PERL) { |
473 | # first find path of perl |
644 | # first find path of perl |
474 | my $perl = $; |
645 | my $perl = $^X; |
475 | |
646 | |
476 | # first we try $^X, but the path must be absolute (always on win32), and end in sth. |
647 | # first we try $^X, but the path must be absolute (always on win32), and end in sth. |
477 | # that looks like perl. this obviously only works for posix and win32 |
648 | # that looks like perl. this obviously only works for posix and win32 |
478 | unless ( |
649 | unless ( |
479 | ($^O eq "MSWin32" || $perl =~ m%^/%) |
650 | ($^O eq "MSWin32" || $perl =~ m%^/%) |
480 | && $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i |
651 | && $perl =~ m%[/\\]perl(?:[0-9]+(\.[0-9]+)+)?(\.exe)?$%i |
481 | ) { |
652 | ) { |
482 | # if it doesn't look perlish enough, try Config |
653 | # if it doesn't look perlish enough, try Config |
483 | require Config; |
654 | require Config; |
484 | $perl = $Config::Config{perlpath}; |
655 | $perl = $Config::Config{perlpath}; |
485 | $perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/; |
656 | $perl =~ s/(?:\Q$Config::Config{_exe}\E)?$/$Config::Config{_exe}/; |
|
|
657 | } |
|
|
658 | |
|
|
659 | $PERL = $perl; |
486 | } |
660 | } |
487 | |
661 | |
488 | require Proc::FastSpawn; |
662 | require Proc::FastSpawn; |
489 | |
663 | |
490 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
664 | my ($fh, $slave) = AnyEvent::Util::portable_socketpair; |
… | |
… | |
498 | #local $ENV{PERL5LIB} = join ":", grep !ref, @INC; |
672 | #local $ENV{PERL5LIB} = join ":", grep !ref, @INC; |
499 | my %env = %ENV; |
673 | my %env = %ENV; |
500 | $env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC; |
674 | $env{PERL5LIB} = join +($^O eq "MSWin32" ? ";" : ":"), grep !ref, @INC; |
501 | |
675 | |
502 | my $pid = Proc::FastSpawn::spawn ( |
676 | my $pid = Proc::FastSpawn::spawn ( |
503 | $perl, |
677 | $PERL, |
504 | ["perl", "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$], |
678 | [$PERL, "-MAnyEvent::Fork::Serve", "-e", "AnyEvent::Fork::Serve::me", fileno $slave, $$], |
505 | [map "$_=$env{$_}", keys %env], |
679 | [map "$_=$env{$_}", keys %env], |
506 | ) or die "unable to spawn AnyEvent::Fork server: $!"; |
680 | ) or die "unable to spawn AnyEvent::Fork server: $!"; |
507 | |
681 | |
508 | $self->_new ($fh, $pid) |
682 | $self->_new ($fh, $pid) |
509 | } |
683 | } |
510 | |
684 | |
511 | =item $pid = $proc->pid |
685 | =item $pid = $proc->pid |
512 | |
686 | |
513 | 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 |
514 | 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. |
515 | |
692 | |
516 | 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 |
517 | 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, |
518 | to clean up their zombies when they die. |
695 | you need to check whether a process is a diretc child by calling this |
519 | |
696 | method, and possibly creating a child watcher or reap it manually. |
520 | All other processes are not direct children, and will be cleaned up by |
|
|
521 | AnyEvent::Fork. |
|
|
522 | |
697 | |
523 | =cut |
698 | =cut |
524 | |
699 | |
525 | sub pid { |
700 | sub pid { |
526 | $_[0][0] |
701 | $_[0][PID] |
527 | } |
702 | } |
528 | |
703 | |
529 | =item $proc = $proc->eval ($perlcode, @args) |
704 | =item $proc = $proc->eval ($perlcode, @args) |
530 | |
705 | |
531 | Evaluates the given C<$perlcode> as ... perl code, while setting C<@_> to |
706 | Evaluates the given C<$perlcode> as ... Perl code, while setting C<@_> |
532 | the strings specified by C<@args>, in the "main" package. |
707 | to the strings specified by C<@args>, in the "main" package (so you can |
|
|
708 | access the args using C<$_[0]> and so on, but not using implicit C<shit> |
|
|
709 | as the latter works on C<@ARGV>). |
533 | |
710 | |
534 | This call is meant to do any custom initialisation that might be required |
711 | This call is meant to do any custom initialisation that might be required |
535 | (for example, the C<require> method uses it). It's not supposed to be used |
712 | (for example, the C<require> method uses it). It's not supposed to be used |
536 | to completely take over the process, use C<run> for that. |
713 | to completely take over the process, use C<run> for that. |
537 | |
714 | |
538 | The code will usually be executed after this call returns, and there is no |
715 | The code will usually be executed after this call returns, and there is no |
539 | way to pass anything back to the calling process. Any evaluation errors |
716 | way to pass anything back to the calling process. Any evaluation errors |
540 | will be reported to stderr and cause the process to exit. |
717 | will be reported to stderr and cause the process to exit. |
541 | |
718 | |
542 | If you want to execute some code to take over the process (see the |
719 | If you want to execute some code (that isn't in a module) to take over the |
543 | "fork+exec" example in the SYNOPSIS), you should compile a function via |
720 | process, you should compile a function via C<eval> first, and then call |
544 | C<eval> first, and then call it via C<run>. This also gives you access to |
721 | it via C<run>. This also gives you access to any arguments passed via the |
545 | any arguments passed via the C<send_xxx> methods, such as file handles. |
722 | C<send_xxx> methods, such as file handles. See the L<use AnyEvent::Fork as |
|
|
723 | a faster fork+exec> example to see it in action. |
546 | |
724 | |
547 | Returns the process object for easy chaining of method calls. |
725 | Returns the process object for easy chaining of method calls. |
|
|
726 | |
|
|
727 | It's common to want to call an iniitalisation function with some |
|
|
728 | arguments. Make sure you actually pass C<@_> to that function (for example |
|
|
729 | by using C<&name> syntax), and do not just specify a function name: |
|
|
730 | |
|
|
731 | $proc->eval ('&MyModule::init', $string1, $string2); |
548 | |
732 | |
549 | =cut |
733 | =cut |
550 | |
734 | |
551 | sub eval { |
735 | sub eval { |
552 | my ($self, $code, @args) = @_; |
736 | my ($self, $code, @args) = @_; |
… | |
… | |
576 | =item $proc = $proc->send_fh ($handle, ...) |
760 | =item $proc = $proc->send_fh ($handle, ...) |
577 | |
761 | |
578 | Send one or more file handles (I<not> file descriptors) to the process, |
762 | Send one or more file handles (I<not> file descriptors) to the process, |
579 | to prepare a call to C<run>. |
763 | to prepare a call to C<run>. |
580 | |
764 | |
581 | The process object keeps a reference to the handles until this is done, |
765 | The process object keeps a reference to the handles until they have |
582 | so you must not explicitly close the handles. This is most easily |
766 | been passed over to the process, so you must not explicitly close the |
583 | accomplished by simply not storing the file handles anywhere after passing |
767 | handles. This is most easily accomplished by simply not storing the file |
584 | them to this method. |
768 | handles anywhere after passing them to this method - when AnyEvent::Fork |
|
|
769 | is finished using them, perl will automatically close them. |
585 | |
770 | |
586 | Returns the process object for easy chaining of method calls. |
771 | Returns the process object for easy chaining of method calls. |
587 | |
772 | |
588 | Example: pass a file handle to a process, and release it without |
773 | Example: pass a file handle to a process, and release it without |
589 | closing. It will be closed automatically when it is no longer used. |
774 | closing. It will be closed automatically when it is no longer used. |
… | |
… | |
596 | sub send_fh { |
781 | sub send_fh { |
597 | my ($self, @fh) = @_; |
782 | my ($self, @fh) = @_; |
598 | |
783 | |
599 | for my $fh (@fh) { |
784 | for my $fh (@fh) { |
600 | $self->_cmd ("h"); |
785 | $self->_cmd ("h"); |
601 | push @{ $self->[2] }, \$fh; |
786 | push @{ $self->[QUEUE] }, \$fh; |
602 | } |
787 | } |
603 | |
788 | |
604 | $self |
789 | $self |
605 | } |
790 | } |
606 | |
791 | |
607 | =item $proc = $proc->send_arg ($string, ...) |
792 | =item $proc = $proc->send_arg ($string, ...) |
608 | |
793 | |
609 | Send one or more argument strings to the process, to prepare a call to |
794 | Send one or more argument strings to the process, to prepare a call to |
610 | C<run>. The strings can be any octet string. |
795 | C<run>. The strings can be any octet strings. |
611 | |
796 | |
612 | The protocol is optimised to pass a moderate number of relatively short |
797 | The protocol is optimised to pass a moderate number of relatively short |
613 | strings - while you can pass up to 4GB of data in one go, this is more |
798 | strings - while you can pass up to 4GB of data in one go, this is more |
614 | meant to pass some ID information or other startup info, not big chunks of |
799 | meant to pass some ID information or other startup info, not big chunks of |
615 | data. |
800 | data. |
… | |
… | |
631 | Enter the function specified by the function name in C<$func> in the |
816 | Enter the function specified by the function name in C<$func> in the |
632 | process. The function is called with the communication socket as first |
817 | process. The function is called with the communication socket as first |
633 | argument, followed by all file handles and string arguments sent earlier |
818 | argument, followed by all file handles and string arguments sent earlier |
634 | via C<send_fh> and C<send_arg> methods, in the order they were called. |
819 | via C<send_fh> and C<send_arg> methods, in the order they were called. |
635 | |
820 | |
|
|
821 | The process object becomes unusable on return from this function - any |
|
|
822 | further method calls result in undefined behaviour. |
|
|
823 | |
636 | The function name should be fully qualified, but if it isn't, it will be |
824 | The function name should be fully qualified, but if it isn't, it will be |
637 | looked up in the main package. |
825 | looked up in the C<main> package. |
638 | |
826 | |
639 | If the called function returns, doesn't exist, or any error occurs, the |
827 | If the called function returns, doesn't exist, or any error occurs, the |
640 | process exits. |
828 | process exits. |
641 | |
829 | |
642 | Preparing the process is done in the background - when all commands have |
830 | Preparing the process is done in the background - when all commands have |
643 | been sent, the callback is invoked with the local communications socket |
831 | been sent, the callback is invoked with the local communications socket |
644 | as argument. At this point you can start using the socket in any way you |
832 | as argument. At this point you can start using the socket in any way you |
645 | like. |
833 | like. |
646 | |
834 | |
647 | The process object becomes unusable on return from this function - any |
|
|
648 | further method calls result in undefined behaviour. |
|
|
649 | |
|
|
650 | If the communication socket isn't used, it should be closed on both sides, |
835 | If the communication socket isn't used, it should be closed on both sides, |
651 | to save on kernel memory. |
836 | to save on kernel memory. |
652 | |
837 | |
653 | The socket is non-blocking in the parent, and blocking in the newly |
838 | The socket is non-blocking in the parent, and blocking in the newly |
654 | created process. The close-on-exec flag is set in both. |
839 | created process. The close-on-exec flag is set in both. |
655 | |
840 | |
656 | Even if not used otherwise, the socket can be a good indicator for the |
841 | Even if not used otherwise, the socket can be a good indicator for the |
657 | existence of the process - if the other process exits, you get a readable |
842 | existence of the process - if the other process exits, you get a readable |
658 | event on it, because exiting the process closes the socket (if it didn't |
843 | event on it, because exiting the process closes the socket (if it didn't |
659 | create any children using fork). |
844 | create any children using fork). |
|
|
845 | |
|
|
846 | =over 4 |
|
|
847 | |
|
|
848 | =item Compatibility to L<AnyEvent::Fork::Remote> |
|
|
849 | |
|
|
850 | If you want to write code that works with both this module and |
|
|
851 | L<AnyEvent::Fork::Remote>, you need to write your code so that it assumes |
|
|
852 | there are two file handles for communications, which might not be unix |
|
|
853 | domain sockets. The C<run> function should start like this: |
|
|
854 | |
|
|
855 | sub run { |
|
|
856 | my ($rfh, @args) = @_; # @args is your normal arguments |
|
|
857 | my $wfh = fileno $rfh ? $rfh : *STDOUT; |
|
|
858 | |
|
|
859 | # now use $rfh for reading and $wfh for writing |
|
|
860 | } |
|
|
861 | |
|
|
862 | This checks whether the passed file handle is, in fact, the process |
|
|
863 | C<STDIN> handle. If it is, then the function was invoked visa |
|
|
864 | L<AnyEvent::Fork::Remote>, so STDIN should be used for reading and |
|
|
865 | C<STDOUT> should be used for writing. |
|
|
866 | |
|
|
867 | In all other cases, the function was called via this module, and there is |
|
|
868 | only one file handle that should be sued for reading and writing. |
|
|
869 | |
|
|
870 | =back |
660 | |
871 | |
661 | Example: create a template for a process pool, pass a few strings, some |
872 | Example: create a template for a process pool, pass a few strings, some |
662 | file handles, then fork, pass one more string, and run some code. |
873 | file handles, then fork, pass one more string, and run some code. |
663 | |
874 | |
664 | my $pool = AnyEvent::Fork |
875 | my $pool = AnyEvent::Fork |
… | |
… | |
692 | =cut |
903 | =cut |
693 | |
904 | |
694 | sub run { |
905 | sub run { |
695 | my ($self, $func, $cb) = @_; |
906 | my ($self, $func, $cb) = @_; |
696 | |
907 | |
697 | $self->[4] = $cb; |
908 | $self->[CB] = $cb; |
698 | $self->_cmd (r => $func); |
909 | $self->_cmd (r => $func); |
|
|
910 | } |
|
|
911 | |
|
|
912 | =back |
|
|
913 | |
|
|
914 | |
|
|
915 | =head2 CHILD PROCESS INTERFACE |
|
|
916 | |
|
|
917 | This module has a limited API for use in child processes. |
|
|
918 | |
|
|
919 | =over 4 |
|
|
920 | |
|
|
921 | =item @args = AnyEvent::Fork::Serve::run_args |
|
|
922 | |
|
|
923 | This function, which only exists before the C<run> method is called, |
|
|
924 | returns the arguments that would be passed to the run function, and clears |
|
|
925 | them. |
|
|
926 | |
|
|
927 | This is mainly useful to get any file handles passed via C<send_fh>, but |
|
|
928 | works for any arguments passed via C<< send_I<xxx> >> methods. |
|
|
929 | |
|
|
930 | =back |
|
|
931 | |
|
|
932 | |
|
|
933 | =head2 EXPERIMENTAL METHODS |
|
|
934 | |
|
|
935 | These methods might go away completely or change behaviour, at any time. |
|
|
936 | |
|
|
937 | =over 4 |
|
|
938 | |
|
|
939 | =item $proc->to_fh ($cb->($fh)) # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
940 | |
|
|
941 | Flushes all commands out to the process and then calls the callback with |
|
|
942 | the communications socket. |
|
|
943 | |
|
|
944 | The process object becomes unusable on return from this function - any |
|
|
945 | further method calls result in undefined behaviour. |
|
|
946 | |
|
|
947 | The point of this method is to give you a file handle that you can pass |
|
|
948 | to another process. In that other process, you can call C<new_from_fh |
|
|
949 | AnyEvent::Fork $fh> to create a new C<AnyEvent::Fork> object from it, |
|
|
950 | thereby effectively passing a fork object to another process. |
|
|
951 | |
|
|
952 | =cut |
|
|
953 | |
|
|
954 | sub to_fh { |
|
|
955 | my ($self, $cb) = @_; |
|
|
956 | |
|
|
957 | $self->[CB] = $cb; |
|
|
958 | |
|
|
959 | unless ($self->[WW]) { |
|
|
960 | $self->[CB]->($self->[FH]); |
|
|
961 | @$self = (); |
|
|
962 | } |
|
|
963 | } |
|
|
964 | |
|
|
965 | =item new_from_fh AnyEvent::Fork $fh # EXPERIMENTAL, MIGHT BE REMOVED |
|
|
966 | |
|
|
967 | Takes a file handle originally rceeived by the C<to_fh> method and creates |
|
|
968 | a new C<AnyEvent:Fork> object. The child process itself will not change in |
|
|
969 | any way, i.e. it will keep all the modifications done to it before calling |
|
|
970 | C<to_fh>. |
|
|
971 | |
|
|
972 | The new object is very much like the original object, except that the |
|
|
973 | C<pid> method will return C<undef> even if the process is a direct child. |
|
|
974 | |
|
|
975 | =cut |
|
|
976 | |
|
|
977 | sub new_from_fh { |
|
|
978 | my ($class, $fh) = @_; |
|
|
979 | |
|
|
980 | $class->_new ($fh) |
699 | } |
981 | } |
700 | |
982 | |
701 | =back |
983 | =back |
702 | |
984 | |
703 | =head1 PERFORMANCE |
985 | =head1 PERFORMANCE |
… | |
… | |
713 | |
995 | |
714 | 2079 new processes per second, using manual socketpair + fork |
996 | 2079 new processes per second, using manual socketpair + fork |
715 | |
997 | |
716 | Then I did the same thing, but instead of calling fork, I called |
998 | Then I did the same thing, but instead of calling fork, I called |
717 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
999 | AnyEvent::Fork->new->run ("CORE::exit") and then again waited for the |
718 | socket form the child to close on exit. This does the same thing as manual |
1000 | socket from the child to close on exit. This does the same thing as manual |
719 | socket pair + fork, except that what is forked is the template process |
1001 | socket pair + fork, except that what is forked is the template process |
720 | (2440kB), and the socket needs to be passed to the server at the other end |
1002 | (2440kB), and the socket needs to be passed to the server at the other end |
721 | of the socket first. |
1003 | of the socket first. |
722 | |
1004 | |
723 | 2307 new processes per second, using AnyEvent::Fork->new |
1005 | 2307 new processes per second, using AnyEvent::Fork->new |
… | |
… | |
728 | 479 vfork+execs per second, using AnyEvent::Fork->new_exec |
1010 | 479 vfork+execs per second, using AnyEvent::Fork->new_exec |
729 | |
1011 | |
730 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
1012 | So how can C<< AnyEvent->new >> be faster than a standard fork, even |
731 | though it uses the same operations, but adds a lot of overhead? |
1013 | though it uses the same operations, but adds a lot of overhead? |
732 | |
1014 | |
733 | The difference is simply the process size: forking the 6MB process takes |
1015 | The difference is simply the process size: forking the 5MB process takes |
734 | so much longer than forking the 2.5MB template process that the overhead |
1016 | so much longer than forking the 2.5MB template process that the extra |
735 | introduced is canceled out. |
1017 | overhead is canceled out. |
736 | |
1018 | |
737 | If the benchmark process grows, the normal fork becomes even slower: |
1019 | If the benchmark process grows, the normal fork becomes even slower: |
738 | |
1020 | |
739 | 1340 new processes, manual fork in a 20MB process |
1021 | 1340 new processes, manual fork of a 20MB process |
740 | 731 new processes, manual fork in a 200MB process |
1022 | 731 new processes, manual fork of a 200MB process |
741 | 235 new processes, manual fork in a 2000MB process |
1023 | 235 new processes, manual fork of a 2000MB process |
742 | |
1024 | |
743 | What that means (to me) is that I can use this module without having a |
1025 | What that means (to me) is that I can use this module without having a bad |
744 | very bad conscience because of the extra overhead required to start new |
1026 | conscience because of the extra overhead required to start new processes. |
745 | processes. |
|
|
746 | |
1027 | |
747 | =head1 TYPICAL PROBLEMS |
1028 | =head1 TYPICAL PROBLEMS |
748 | |
1029 | |
749 | This section lists typical problems that remain. I hope by recognising |
1030 | This section lists typical problems that remain. I hope by recognising |
750 | them, most can be avoided. |
1031 | them, most can be avoided. |
751 | |
1032 | |
752 | =over 4 |
1033 | =over 4 |
753 | |
1034 | |
754 | =item "leaked" file descriptors for exec'ed processes |
1035 | =item leaked file descriptors for exec'ed processes |
755 | |
1036 | |
756 | POSIX systems inherit file descriptors by default when exec'ing a new |
1037 | POSIX systems inherit file descriptors by default when exec'ing a new |
757 | process. While perl itself laudably sets the close-on-exec flags on new |
1038 | process. While perl itself laudably sets the close-on-exec flags on new |
758 | file handles, most C libraries don't care, and even if all cared, it's |
1039 | file handles, most C libraries don't care, and even if all cared, it's |
759 | often not possible to set the flag in a race-free manner. |
1040 | often not possible to set the flag in a race-free manner. |
… | |
… | |
779 | libraries or the code that leaks those file descriptors. |
1060 | libraries or the code that leaks those file descriptors. |
780 | |
1061 | |
781 | Fortunately, most of these leaked descriptors do no harm, other than |
1062 | Fortunately, most of these leaked descriptors do no harm, other than |
782 | sitting on some resources. |
1063 | sitting on some resources. |
783 | |
1064 | |
784 | =item "leaked" file descriptors for fork'ed processes |
1065 | =item leaked file descriptors for fork'ed processes |
785 | |
1066 | |
786 | Normally, L<AnyEvent::Fork> does start new processes by exec'ing them, |
1067 | Normally, L<AnyEvent::Fork> does start new processes by exec'ing them, |
787 | which closes file descriptors not marked for being inherited. |
1068 | which closes file descriptors not marked for being inherited. |
788 | |
1069 | |
789 | However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer |
1070 | However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer |
… | |
… | |
798 | |
1079 | |
799 | The solution is to either not load these modules before use'ing |
1080 | The solution is to either not load these modules before use'ing |
800 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay |
1081 | L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay |
801 | initialising them, for example, by calling C<init Gtk2> manually. |
1082 | initialising them, for example, by calling C<init Gtk2> manually. |
802 | |
1083 | |
803 | =item exit runs destructors |
1084 | =item exiting calls object destructors |
804 | |
1085 | |
805 | This only applies to users of Lc<AnyEvent::Fork:Early> and |
1086 | This only applies to users of L<AnyEvent::Fork:Early> and |
806 | L<AnyEvent::Fork::Template>. |
1087 | L<AnyEvent::Fork::Template>, or when initialising code creates objects |
|
|
1088 | that reference external resources. |
807 | |
1089 | |
808 | When a process created by AnyEvent::Fork exits, it might do so by calling |
1090 | When a process created by AnyEvent::Fork exits, it might do so by calling |
809 | exit, or simply letting perl reach the end of the program. At which point |
1091 | exit, or simply letting perl reach the end of the program. At which point |
810 | Perl runs all destructors. |
1092 | Perl runs all destructors. |
811 | |
1093 | |
… | |
… | |
830 | to make it so, mostly due to the bloody broken perl that nobody seems to |
1112 | to make it so, mostly due to the bloody broken perl that nobody seems to |
831 | care about. The fork emulation is a bad joke - I have yet to see something |
1113 | care about. The fork emulation is a bad joke - I have yet to see something |
832 | useful that you can do with it without running into memory corruption |
1114 | useful that you can do with it without running into memory corruption |
833 | issues or other braindamage. Hrrrr. |
1115 | issues or other braindamage. Hrrrr. |
834 | |
1116 | |
835 | Cygwin perl is not supported at the moment, as it should implement fd |
1117 | Since fork is endlessly broken on win32 perls (it doesn't even remotely |
836 | passing, but doesn't, and rolling my own is hard, as cygwin doesn't |
1118 | work within it's documented limits) and quite obviously it's not getting |
837 | support enough functionality to do it. |
1119 | improved any time soon, the best way to proceed on windows would be to |
|
|
1120 | always use C<new_exec> and thus never rely on perl's fork "emulation". |
|
|
1121 | |
|
|
1122 | Cygwin perl is not supported at the moment due to some hilarious |
|
|
1123 | shortcomings of its API - see L<IO::FDPoll> for more details. If you never |
|
|
1124 | use C<send_fh> and always use C<new_exec> to create processes, it should |
|
|
1125 | work though. |
|
|
1126 | |
|
|
1127 | =head1 USING AnyEvent::Fork IN SUBPROCESSES |
|
|
1128 | |
|
|
1129 | AnyEvent::Fork itself cannot generally be used in subprocesses. As long as |
|
|
1130 | only one process ever forks new processes, sharing the template processes |
|
|
1131 | is possible (you could use a pipe as a lock by writing a byte into it to |
|
|
1132 | unlock, and reading the byte to lock for example) |
|
|
1133 | |
|
|
1134 | To make concurrent calls possible after fork, you should get rid of the |
|
|
1135 | template and early fork processes. AnyEvent::Fork will create a new |
|
|
1136 | template process as needed. |
|
|
1137 | |
|
|
1138 | undef $AnyEvent::Fork::EARLY; |
|
|
1139 | undef $AnyEvent::Fork::TEMPLATE; |
|
|
1140 | |
|
|
1141 | It doesn't matter whether you get rid of them in the parent or child after |
|
|
1142 | a fork. |
838 | |
1143 | |
839 | =head1 SEE ALSO |
1144 | =head1 SEE ALSO |
840 | |
1145 | |
841 | L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter), |
1146 | L<AnyEvent::Fork::Early>, to avoid executing a perl interpreter at all |
|
|
1147 | (part of this distribution). |
|
|
1148 | |
842 | L<AnyEvent::Fork::Template> (to create a process by forking the main |
1149 | L<AnyEvent::Fork::Template>, to create a process by forking the main |
843 | program at a convenient time). |
1150 | program at a convenient time (part of this distribution). |
844 | |
1151 | |
845 | =head1 AUTHOR |
1152 | L<AnyEvent::Fork::Remote>, for another way to create processes that is |
|
|
1153 | mostly compatible to this module and modules building on top of it, but |
|
|
1154 | works better with remote processes. |
|
|
1155 | |
|
|
1156 | L<AnyEvent::Fork::RPC>, for simple RPC to child processes (on CPAN). |
|
|
1157 | |
|
|
1158 | L<AnyEvent::Fork::Pool>, for simple worker process pool (on CPAN). |
|
|
1159 | |
|
|
1160 | =head1 AUTHOR AND CONTACT INFORMATION |
846 | |
1161 | |
847 | Marc Lehmann <schmorp@schmorp.de> |
1162 | Marc Lehmann <schmorp@schmorp.de> |
848 | http://home.schmorp.de/ |
1163 | http://software.schmorp.de/pkg/AnyEvent-Fork |
849 | |
1164 | |
850 | =cut |
1165 | =cut |
851 | |
1166 | |
852 | 1 |
1167 | 1 |
853 | |
1168 | |