RE: [Ssh-sftp-perl-users] are net::ssh::perl and net::sftp considered thread safe?

[Yishay W. <yis...@ho...>]

These are the problems I encounter on win2k ActivePerl 5.8.7 using 
Net-SSH-Perl [1.23_01]

when using fork():

For this code:

===============================

use Net::SSH::W32Perl;
use strict;

my $user = 'user';
my $password = 'password';
my $fileName = "~$user/dummy_file2";

my $ssh = createSsh();

my $i = 1;
while (1)
{
	print "starting...\n";
	runInLoop();
	print "sleeping 10\n";
	sleep 10;
	print "finished iteration ".$i++."\n";
}

sub isRunning {
	my $ssh = shift;
	my ($out, $err, $exit) = $ssh->cmd("ls $fileName");
#	print "out: $out\nerr: $err\nexit: $exit\n";
	return !$err && $out;
}

sub createSsh
{
	my $time = time();
	my $ssh = Net::SSH::W32Perl->new('host');
	$ssh->login($user, $password);
	print "ssh created after ", time() - $time, "\n";
	return $ssh;
}

sub runInLoop
{
	my $time = time();
	my ($out, $err, $exit) = $ssh->cmd("rm $fileName");
	if (isRunning($ssh) )
	{
		print "error removing $fileName\n";
		return;
	}
	my $ssh2 = createSsh();
	unless (my $pid = fork() )
	{
		startAction($ssh2);
		while (1) {}
	} else {
		print "out of command after ", time - $time, "\n";
		my $isRunning = isRunning($ssh);
		sleep 5;
		kill (9, $pid);
		while (time() - $time < 60)
		{
			last if ($isRunning = isRunning($ssh) );
		}
		my $howlong = time() - $time;
		if ($isRunning) {
			print "start was successful after $howlong\n";
		} else {
			print "failed after $howlong\n";
		}
	}
}

sub startAction
{
	my $ssh2 = shift;
	my $cmd = "sleep 20; touch $fileName; sleep 60; ";
	print "executing cmd: $cmd\n";
	my ($out, $err, $exit) = $ssh2->cmd($cmd);
}

========================

I get:

========================

C:\yishay>perl test_fork.pl
ssh created after 2
starting...
ssh created after 0
out of command after 1
executing cmd: sleep 20; touch ~yishayw/dummy_file2; sleep 60;
Bad packet length 1927540882 at C:/Perl/site/lib/Net/SSH/Perl/Packet.pm line 
171

Bad packet length 1523729943 at C:/Perl/site/lib/Net/SSH/Perl/Packet.pm line 
171


C:\yishay>perl test_fork.pl
ssh created after 0
starting...
ssh created after 0
out of command after 1
executing cmd: sleep 20; touch ~yishayw/dummy_file2; sleep 60;
Corrupted MAC on input at C:/Perl/site/lib/Net/SSH/Perl/Packet.pm line 189
Corrupted MAC on input at C:/Perl/site/lib/Net/SSH/Perl/Packet.pm line 189

=====================================

similar problems happen when using threads instead of fork().

Note that the same code appears to work fine on WinXP for fork(), but not 
using threads.

I also tried using alarm signals on both platforms and did not get the 
desired results - alarm just didn't seem to go off.

So my conclusion is: for non-blocking operations on windows using 
Net::SSH::Perl you can use fork() on XP but there's no solution for win2K. 
If anyone cares to challenge that assumption she'd be most welcome.

Thanks,
Yishay

>From: "Yishay Weiss" <yis...@ho...>
>To: ssh...@li...
>Subject: [Ssh-sftp-perl-users] are net::ssh::perl and net::sftp considered 
>thread safe?
>Date: Sun, 19 Jun 2005 09:22:38 +0000
>
>Hi,
>
>In order to use net::ssh::perl and net::sftp in a non blocking fashion I'm 
>considering using them with threads. I first would like to know if it's 
>considered safe. I'm using perl 5.8 on windows.
>
>I already tried using fork() for the same purpose but encountered some 
>problems on win2k. I would sometimes get an error message. I can't 
>currently reconstruct the problem I had with fork(). I might give more 
>precise info in a separate post. I was only wondering if anyone's tried 
>using threads for this purpose or if a different non-fork() solution 
>exists. Using expect.pm seems like overkill for me, anyway it appears to 
>just be a variation of the fork() solution if I'm correct.
>
>Thanks,
>Yishay
>
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