| Subject: | sometimes loops doing select/read on stdin |
| Date: | Sat, 13 Jan 2007 01:59:42 -0500 (EST) |
| To: | bug-net-sftp [...] rt.cpan.org |
| From: | Chaskiel M Grundman <cg2v [...] andrew.cmu.edu> |
I use Net::SFTP in a batch job. Sometimes (I have not identified the
trigger), I will find that the script is hung. truss shows a poll/read
loop, reading from a fd opened to /dev/null.
I eventually figured out that this fd was dup()'d from stdin by
Net::SSH::Perl:SSH2::_session_channel. Thinking it was silly for the
non-interactive sftp session to have a stdin/stdout/stderr, I replaced the
_session_channel call in Net::SFTP::_open_channel
with
my $cmgr = $ssh->channel_mgr;
my $channel = $cmgr->new_channel(
ctype => 'session', local_window => 32*1024,
local_maxpacket => 16*1024, remote_name => 'client-session');
But that didn't work; Net::SFTP->new hung selecting the tcp socket. After
some trial and error, I determined that Net::SSH::Perl will not call the
_output_buffer handler unless there's a wfd socket that selects as
writable. I provided a /dev/null socket as wfd, did not provide rfd or
efd, and things started working again. I won't know for weeks or months
wether this actually fixes the read-from-/dev/null issue (which is
probably the same problem as bug#7481 in Net::SSH::Perl)
Here's the patch I'm using:
--- lib/Net/SFTP.pm Sat Jan 13 00:41:38 2007
+++ lib/Net/SFTP.pm Sat Jan 13 01:41:32 2007
@@ -9,6 +9,7 @@
use Net::SFTP::Buffer;
use Net::SSH::Perl::Constants qw( :msg2 );
use Net::SSH::Perl 1.24;
+use IO::File;
use Carp qw( carp croak );
@@ -74,8 +75,14 @@
sub _open_channel {
my $sftp = shift;
my $ssh = $sftp->{ssh};
+ my $cmgr = $ssh->channel_mgr;
- my $channel = $ssh->_session_channel;
+ my $channel = $cmgr->new_channel(
+ ctype => 'session', local_window => 32*1024,
+ local_maxpacket => 16*1024, remote_name => 'client-session',
+ wfd => new IO::File '> /dev/null');
+
+# my $channel = $ssh->_session_channel;
$channel->open;
$channel->register_handler(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, sub {