I have chosen to use backticks while the thread has to wait on the completion of the external command.

I also find backticks simplest for many purposes.

The primary advantage of using the piped-open is that it allows you to inject code -- time out; remote abort etc. -- into the read loop:

my $pid = open CMD, '-|', $command or die $!;
my $timeout = time() + 10; ## 10 seconds should be enough
my $output = '';
while( <CMD> ) {
    $output .= $_;
    last if $sharedFlag == ABORT;
    kill 9, $Pid, last if time() > $timeout;
}
close CMD;
return $output;
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It's not perfect. If the child process stops producing output, it will hang at the read, but it is good for most things.

The next level is to use Win32::SocketPair::open2_5() to obtain a handle that can be set non-blocking and use select or sysread to avoid the hang.

A similar thing can be done directly on *nix.

My conclusion, do not use IPC::Run3 or Capture::Tiny in multi threaded scripts.

I concur. Though I would also go further and remove the qualification; both modules (and all the others attempting to do the same thing) are just so overcomplicated that they create more problems than they attempt (and fail) to solve.