an alternative aproach is to pipe STDERR through another command/process that timestamps every line. You will loose some precission, but it would work for any output, even if it's genetated from some XS module.

You can also do further processing of the output easily. For example, the code below copies STDERR to some file while adding a timestamp and removing ANSI color escape sequences from the data.

$0=~m|([^/]*)$|;
my $name=$1;
our $filename="/tmp/debug-$name.out";

my $pid=open STDERR, "|-";
if (defined $pid and $pid==0) {
  print "writing output to $filename\n";
  open (TEE,">$filename");
  select TEE; $|=1;
  print TEE "$0 started at ".`date`."\n";
  select STDERR;
  my $ESC=quotemeta "\033[";
  while(<STDIN>) {
    my $line=$_;
    my ($sec, $min, $hour)=gmtime;
    print STDERR $line;
    $line=~s|$ESC.*?m||go;
    printf TEE "%02d:%02d:%02d| %s",$hour,$min,$sec,$line;
  }
  exit(0);
}
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