1MCE::Signal(3) User Contributed Perl Documentation MCE::Signal(3)
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6 MCE::Signal - Temporary directory creation/cleanup and signal handling
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9 This document describes MCE::Signal version 1.874
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12 ## Creates tmp_dir under $ENV{TEMP} if defined, otherwise /tmp.
13 use MCE::Signal;
15 ## Attempts to create tmp_dir under /dev/shm if writable.
17 use MCE::Signal qw( -use_dev_shm );
19 ## Keeps tmp_dir after the script terminates.
21 use MCE::Signal qw( -keep_tmp_dir );
23 use MCE::Signal qw( -use_dev_shm -keep_tmp_dir );
24 ## MCE loads MCE::Signal by default when not present.
26 ## Therefore, load MCE::Signal first for options to take effect.
27 use MCE::Signal qw( -keep_tmp_dir -use_dev_shm );
29 use MCE;
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32 This package configures $SIG{ HUP, INT, PIPE, QUIT, and TERM } to point
33 to stop_and_exit and creates a temporary directory. The main process
34 and workers receiving said signals call stop_and_exit, which signals
35 all workers to terminate, removes the temporary directory unless
36 -keep_tmp_dir is specified, and terminates itself.
37 The location of the temp directory resides under $ENV{TEMP} if defined,
39 otherwise /dev/shm if writeable and -use_dev_shm is specified, or /tmp.
40 On Windows, the temp directory is made under $ENV{TEMP}/Perl-MCE/.
41 As of MCE 1.405, MCE::Signal no longer calls setpgrp by default. Pass
43 the -setpgrp option to MCE::Signal to call setpgrp.
44 ## Running MCE through Daemon::Control requires setpgrp to be called
46 ## for MCE releases 1.511 and below.
47 use MCE::Signal qw(-setpgrp); ## Not necessary for MCE 1.512 and above
49 use MCE;
50 The following are available options and their meanings.
52 -keep_tmp_dir - The temporary directory is not removed during exiting
54 A message is displayed with the location afterwards
55 -use_dev_shm - Create the temporary directory under /dev/shm
57 -no_kill9 - Do not kill -9 after receiving a signal to terminate
58 -setpgrp - Calls setpgrp to set the process group for the process
60 This option ensures all workers terminate when reading
61 STDIN for MCE releases 1.511 and below.
62 cat big_input_file | ./mce_script.pl | head -10
64 This works fine without the -setpgrp option:
66 ./mce_script.pl < big_input_file | head -10
68 Nothing is exported by default. Exportable are 1 variable and 2
70 subroutines.
71 use MCE::Signal qw( $tmp_dir stop_and_exit sys_cmd );
73 use MCE::Signal qw( :all );
74 $tmp_dir - Path to the temporary directory.
76 stop_and_exit - Described below
77 sys_cmd - Described below
78 stop_and_exit ( [ $exit_status | $signal ] )
80 Stops execution, removes temp directory, and exits the entire
81 application. Pass 'INT' to terminate a spawned or running MCE session.
82 MCE::Signal::stop_and_exit(1);
84 MCE::Signal::stop_and_exit('INT');
85 sys_cmd ( $command )
87 The system function in Perl ignores SIGINT and SIGQUIT. These 2 signals
88 are sent to the command being executed via system() but not back to the
89 underlying Perl script. For this reason, sys_cmd was added to
90 MCE::Signal.
91 ## Execute command and return the actual exit status. The perl script
93 ## is also signaled if command caught SIGINT or SIGQUIT.
94 use MCE::Signal qw(sys_cmd); ## Include before MCE
96 use MCE;
97 my $exit_status = sys_cmd($command);
99
101 defer ( $signal )
102 Returns immediately inside a signal handler if signaled during IPC.
103 The signal is deferred momentarily and re-signaled automatically upon
104 completing IPC. Currently, all IPC related methods in "MCE::Shared" and
105 one method "send2" in "MCE::Channel" set the flag $MCE::Signal::IPC
106 before initiating IPC.
107 Current API available since 1.863.
109 sub sig_handler {
111 return MCE::Signal::defer($_[0]) if $MCE::Signal::IPC;
112 ...
113 }
114 In a nutshell, "defer" helps safeguard IPC from stalling between
116 workers and the shared manager-process. The following is a
117 demonstration for Unix platforms. Deferring the signal inside the
118 "WINCH" handler prevents the app from eventually failing while resizing
119 the window.
120 use strict;
122 use warnings;
123 use MCE::Hobo;
125 use MCE::Shared;
126 use Time::HiRes 'sleep';
127 my $count = MCE::Shared->scalar(0);
129 my $winch = MCE::Shared->scalar(0);
130 my $done = MCE::Shared->scalar(0);
131 $SIG{WINCH} = sub {
133 # defer signal if signaled during IPC
134 return MCE::Signal::defer($_[0]) if $MCE::Signal::IPC;
135 # mask signal handler
137 local $SIG{$_[0]} = 'IGNORE';
138 printf "inside winch handler %d\n", $winch->incr;
140 };
141 $SIG{INT} = sub {
143 # defer signal if signaled during IPC
144 return MCE::Signal::defer($_[0]) if $MCE::Signal::IPC;
145 # set flag for workers to leave loop
147 $done->set(1);
148 };
149 sub task {
151 while ( ! $done->get ) {
152 $count->incr;
153 sleep 0.03;
154 };
155 }
156 print "Resize the terminal window continuously.\n";
158 print "Press Ctrl-C to stop.\n";
159 MCE::Hobo->create('task') for 1..8;
161 sleep 0.015 until $done->get;
162 MCE::Hobo->wait_all;
163 printf "\ncount incremented %d times\n\n", $count->get;
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167 MCE, MCE::Core
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170 Mario E. Roy, <marioeroy AT gmail DOT com>
171perl v5.34.0 2021-07-22 MCE::Signal(3)