| … | |
… | |
| 340 | =head2 CHILD PROCESS WATCHERS |
340 | =head2 CHILD PROCESS WATCHERS |
| 341 | |
341 | |
| 342 | You can also watch on a child process exit and catch its exit status. |
342 | You can also watch on a child process exit and catch its exit status. |
| 343 | |
343 | |
| 344 | The child process is specified by the C<pid> argument (if set to C<0>, it |
344 | The child process is specified by the C<pid> argument (if set to C<0>, it |
| 345 | watches for any child process exit). The watcher will trigger as often |
345 | watches for any child process exit). The watcher will triggered only when |
| 346 | as status change for the child are received. This works by installing a |
346 | the child process has finished and an exit status is available, not on |
| 347 | signal handler for C<SIGCHLD>. The callback will be called with the pid |
347 | any trace events (stopped/continued). |
| 348 | and exit status (as returned by waitpid), so unlike other watcher types, |
348 | |
| 349 | you I<can> rely on child watcher callback arguments. |
349 | The callback will be called with the pid and exit status (as returned by |
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350 | waitpid), so unlike other watcher types, you I<can> rely on child watcher |
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351 | callback arguments. |
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352 | |
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353 | This watcher type works by installing a signal handler for C<SIGCHLD>, |
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354 | and since it cannot be shared, nothing else should use SIGCHLD or reap |
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355 | random child processes (waiting for specific child processes, e.g. inside |
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356 | C<system>, is just fine). |
| 350 | |
357 | |
| 351 | There is a slight catch to child watchers, however: you usually start them |
358 | There is a slight catch to child watchers, however: you usually start them |
| 352 | I<after> the child process was created, and this means the process could |
359 | I<after> the child process was created, and this means the process could |
| 353 | have exited already (and no SIGCHLD will be sent anymore). |
360 | have exited already (and no SIGCHLD will be sent anymore). |
| 354 | |
361 | |
| … | |
… | |
| 854 | no warnings; |
861 | no warnings; |
| 855 | use strict qw(vars subs); |
862 | use strict qw(vars subs); |
| 856 | |
863 | |
| 857 | use Carp; |
864 | use Carp; |
| 858 | |
865 | |
| 859 | our $VERSION = 4.233; |
866 | our $VERSION = 4.234; |
| 860 | our $MODEL; |
867 | our $MODEL; |
| 861 | |
868 | |
| 862 | our $AUTOLOAD; |
869 | our $AUTOLOAD; |
| 863 | our @ISA; |
870 | our @ISA; |
| 864 | |
871 | |
