So, how can I kill Bill?!?
The script is as simple as the following:
#!/usr/bin/perl
use strict;
my $self;
# Maximum execution time (in sec) of the child process. When that timer expires, we send a kill command to the child process
my $MAX_EXEC_TIME = 10;
eval {
# When the alarm interrupt is triggered, send the timed out\n message to the die function
local $SIG{'ALRM'} = sub { die "timed out\n" };
# Set ALARM to interrupt after MAX_EXEC_TIME seconds
alarm($MAX_EXEC_TIME);
print "Starting process bill.pl\n";
# Start child process in asynch mode and get the child process id
$self->{PID} = system 1, "perl bill.pl";
print "Child Pid = $self->{PID}\n";
# Wait for the child to terminate. If it ends before the ALARM is triggered, the process continues from *SECTION1*
waitpid $self->{PID}, 0;
};
if ($@) {
if ($@ eq "timed out\n") {
# *SECTION2* The child process didn't return within the MAX_EXEC_TIME, let's kill it
print "I timed out and killed pid $self->{PID}\n";
if ($self->{PID})
{
# Send a SIGTERM message to let the process try to exit cleanly
kill(15,$self->{PID});
}
$self->{PID} = undef;
}
else {
print "something else happened: $@\n";
}
}
else {
# *SECTION1* The child process terminated before the ALARM interrupt was triggered
print "Child process terminated as expected. I can keep going...\n";
}
...and our Bill process is a simple infinite loop:
#!/usr/bin/perl
while(1) {
print "alive\n";
sleep(2);
}
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