(Win32) Timing out a process while reading process' output?
From: rtm (mclay_at_cfdlab.ae.utexas.edu)
Date: 09/28/04
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Date: Tue, 28 Sep 2004 16:54:58 GMT
I am interested in running a process with a timeout. Also I'm
interested in analyzing the output of this process.
Under Unix, the solution is described clearly in the Perl Cookbook
"16.10: Communicating between related processes" and 16.24 "Timing
out an Operation". Enclosed below is an example showing what I want
to do under Unix.
I need to do this under Windows XP. As others have pointed out
"alarm" works under 5.8+ and fork sorta works under 5.8+ under
windows. But the unix example code below just hangs.
So the best thing I have found is Win32::Job.
------------------------------------------------------------------------
#!/usr/bin/env perl
# -*- cperl -*-
BEGIN { $^W = 1; }
use strict;
use Win32::Job;
my $job = Win32::Job->new();
my $r = $job->spawn("z:\t\junk.exe", "junk", {
stdin => 'NUL', # the NUL device
stdout => 'stdout.log',
stderr => 'stdout.log',
});
$job->run(20);
------------------------------------------------------------------------
The only problem is that I can't see how you read the output while the
process is running when using Win32::Job. Of course one can write the
output to a file then read it back in after the process is finished.
Is there another way? Is there another Win32:: something that does
what I want?
Thanks
------------------------------------------------------------------------
#!/usr/bin/env perl
# -*- cperl -*-
BEGIN { $^W = 1; }
use strict;
use IO::Handle;
pipe(READER, WRITER);
WRITER->autoflush(1);
$SIG{CHLD} = 'IGNORE';
my $pid;
eval
{
local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required
alarm 20;
die "Can't fork: $!" unless defined($pid = fork);
if ($pid)
{
# parent
close WRITER;
while(<READER>)
{
print "Got: $_";
}
}
else
{
close READER;
open(STDOUT, ">&WRITER");
exec("junk","","") or die("exec $!");
}
alarm 0;
waitpid($pid,0);
};
if ($@)
{
die unless $@ eq "alarm\n"; # propagate unexpected errors
print "Tripped Alarm\n";
kill 9, $pid;
}
------------------------------------------------------------------------
#include <stdio.h>
#include <math.h>
int main()
{
int i,j,n;
double x,y, dx;
FILE* fp = fopen("junk.log","w");
n = 1000000;
dx = 0.00001;
x = 0.0;
for (j = 0; j < 50; j++)
{
for (i = 0; i < n; i++)
{
y = sin(x);
x += dx;
}
fprintf(fp,"j: %d\n", j);
fflush(fp);
printf("j: %d\n", j);
}
}
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