Re: Threaded or Forked FTP Backup with chdir

[BrowserUk]

The code below almost works except for the chdir(). ... Is there a way to convert this program to use fork().

1. How/why doesn't chdir work for you?
2. How will converting to fork fix the chdir problem?
3. Why is it necessary to chdir? Why not just supply the full path to put?

[Mimir]

1. chdir isn't unique to each thread. If you chdir in one thread they all change.
2. changing to fork would allow chdir per fork because the memory is copied when forked
3. This is an excellent point. You can't pass the full path to put but, you can pass a file handle.

Here is the updated code:

sub worker {
   my $tid = threads->tid;
   my( $Qwork, $Qresults ) = @_;

   my $ftp = Net::FTP->new($gFtpServer, Debug => 0);
   $ftp->login($gFtpUser, $gFtpPass) or print "unable to loging to $gF
+tpServer: $ftp->message\n";

   while(my $work = $Qwork->dequeue) {
      my ($result, $localFile);
      my (@workItem);

      @workItem = split (",", $work);

      chomp($workItem[0]);
      chomp($workItem[1]);
      chomp($workItem[2]);
      print "ftp dir: $workItem[0]\n";
      print "local dir: $workItem[1]\n";
      print "file: $workItem[2]\n";
      $localFile = sprintf("%s%s",$workItem[1],$workItem[2]);

      open (my $fh, "<", $localFile) or print "unable to open file";
      $ftp->cwd($workItem[0]) or print "unable to FTP change dir $work
+Item[0]: $ftp->message\n";
      $ftp->put($fh, $workItem[2]) or print "unable to FTP $workItem[2
+]: $ftp->message\n";
      ## Process $work to produce $result ##
      $result = "$tid : result for workitem ";
      $Qresults->enqueue( $result );
   }
   $Qresults->enqueue( undef ); ## Signal this thread is finished
   $ftp->quit;
}

[BrowserUk]

chdir isn't unique to each thread. If you chdir in one thread they all change.

Ah yes. I'd forgotten about that difference 'tween Windows and *nix.

You can't pass the full path to put ...

Really? Looking inside the module it does a sysopen which handles a fully qualified path just fine on my system.

... but, you can pass a file handle.

Anyway, glad you got a solution.