Interesting. A couple of things:

First, thanks for the response.

Second, it took me some effort to find your response as I had posted the original to "seekers of perl wisdom" but never actually saw it show up anywhere except when I login and look at my "Nodes You Wrote." I finally did a "super search" of everything for "threads XP" in the title and finally discovered your reply-- I still don't know where this discussion thread is actually showing up, as the "super search" didn't seem to tell me *where* it found what it found...

And finally, I'm using AS 813, and your example works for me too. However, what it doesn't do is run multiple threads in parallel-- it just runs a single thread. So, I tweaked it a bit and came up with the attached version of your program. I was running into errors due to sort not being able to access the test.dat file in each thread due to collisions, so I created 4 copies of the test.dat file (test1-4.dat) and also use the scheme for the sorted.dat output file so that the threads won't be using each others files. I then run async 4 times to spawn off 4 threads. I also added a sleep in the thread (probably not necessary) to make sure all 4 threads are running before any of them start doing their thing. After that, the first thread's system() call works, and then the whole thing hangs. If I only run one thread in "spawnem" then it works OK...

#! perl -slw
use strict;
use threads;

sub test {
        my $t = shift;

        my $cmd = "c:/windows/system32/sort.exe test$t.dat";
        
        print "Thread $t\n";  # show things are in motion...

        sleep 1;  # kludge to insure all threads are up...

        system "$cmd >sorted$t.dat";

        open F, "<sorted$t.dat" or die $!;
        print "Via system:\n", do{ local $/; <F> };
        close F;
        
        print "Via backticks\n", `$cmd`;

        open F, "$cmd|" or die $!;
        print "Via pipe\n", <F>;
        close F;
}

sub spawnem
{
    my $t1 = async{ \&test(1); };
    my $t2 = async{ \&test(2); };
    my $t3 = async{ \&test(3); };
    my $t4 = async{ \&test(4); };

    $t1->join;
    $t2->join;
    $t3->join;
    $t4->join;
}

&spawnem;

[download]

In reply to Re^2: Behavior of threads on XP-- system() works, backtic & popen don't... by Sync
in thread Behavior of threads on XP-- system() works, backtic & popen don't... by Sync

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