----- Original Message -----
From: "Craig DeForest" <[email protected]>
To: "Sisyphus" <[email protected]>
Cc: "Craig DeForest" <[email protected]>; "[email protected]
list" <[email protected]>
Sent: Thursday, December 08, 2011 4:53 PM
Subject: Re: [Perldl] Gnuplot beta test - dist file included in message
Thanks for doing this, Rob!
Hmmm, it appears that there is an IPC issue going on. I wonder whether
it is deadlocking somehow.
I'll try to dive into the Run::IPC module to look for likely trouble
spots.
Had a bit of a further poke at it today and there's a problem with
IO::Select's can_read() method in that it just doesn't work on Windows,
afaict.
It returns immediately (irrespective of what value, if any, is assigned to
the timeout). Turns out that error message about gnuplot having been
unresponsive for 5 seconds is emitted approx 0.5 seconds after the script
has loaded and starts to execute.
And any array that is designated to collect the return value(s) of
can_read() is always empty.
For a basic test script, I tried:
####################################
use warnings;
use IO::Select;
open(RD, '<', $0) or die "Can't open RD: $!";
$s = IO::Select->new();
$s->add(\*STDIN);
$s->add(\*STDOUT);
$s->add(\*STDERR);
$s->add(\*RD);
if($s->exists(\*STDIN)) {print "ok 1\n"}
if($s->exists(\*STDERR)) {print "ok 2\n"}
if($s->exists(\*STDOUT)) {print "ok 3\n"}
if($s->exists(\*RD)) {print "ok 4\n"}
@r1 = $s->can_read(5);
defined(@r1) ? print "defined\n" : print "not defined\n";
print "\@r1 contains ", scalar(@r1), " elements\n";
#################################
which outputs (for both perl-5.8.9 and 5.14.0) on Windows:
ok 1
ok 2
ok 3
ok 4
not defined
@r1 contains 0 elements
On both Cygwin and linux, the same script outputs:
ok 1
ok 2
ok 3
ok 4
defined
@r1 contains 1 elements
The can_write() method appears to be similarly affected, whereas the
'exists', 'handles', 'count' and 'bits' methods seemed fine (in another test
script that I ran).
I wonder how this can_read functionality can best be accommodated on
Windows.
Cheers,
Rob
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