Ofer Nave wrote:
>> die( Parallel::errplus() );
> Incidentaly, the above should have read "die( Parallel::Simple::errplus );".
> I left out the 'Simple::'. Amazing where you find bugs nowadays. :)
Call me Mr Magoo. I mis-interpreted the 'Bareword "Parallel::errplus"
not allowed while "strict subs" in use' error message when I tried
running your example. In addition to helping people with poor eyesight,
always using () for user-defined function calls means you don't have
to change the code when you switch between "use Parallel::Simple"
and "require Parallel::Simple".
BTW, this slip-up is also a good advertisement for ensuring that your
test suite tests all examples given in your documentation to ensure
that they actually work.
> I'm familiar with the make-up of the 16-bit return value of the system call.
> What I want to learn more about is the possibility that a process could
> crash and yet return a 0 exit code. I had not thought that possible,
> and hence, had seen no need to test for $? & 127.
I did a simple test on Linux.
This is file crash.c:
-------------------------------------------
#include <stdlib.h>
int main(int argc, char* argv[])
{
return 5 / atoi(argv[1]);
}
-------------------------------------------
After compiling with:
cc crash.c
running this Perl program:
use strict;
sub div_by_zero { exec("./a.out $_[0]"); die "should not be here" }
defined(my $pid = fork()) or die "fork: $!";
if ($pid == 0) {
warn "child, my pid $$\n";
div_by_zero(0); # sig 8
# div_by_zero(); # sig 11
exit;
}
warn "parent, my pid $$\n";
waitpid($pid, 0);
my $rv = $? >> 8;
my $sig = $? & 127;
warn "$$: rv=$rv sig=$sig\n";
produces:
parent, my pid 12091
child, my pid 12092
12091: rv=0 sig=8
Replacing div_by_zero() above with:
sub div_by_zero { 5 / shift }
produced:
parent, my pid 12133
child, my pid 12134
Illegal division by zero at g2.pl line 2.
12133: rv=255 sig=0
Perl is catching this one it seems. However, using this one:
sub div_by_zero { warn "sleeping"; sleep(60) }
then manually killing the child process (with SIGTERM), produces:
parent, my pid 12356
child, my pid 12357
sleeping at g2.pl line 3.
12356: rv=0 sig=15
It's pretty rare and no biggie to me, but if I were implementing it
I would check the signal value in addition to the return value.
/-\
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