Re: [JSch-users] JSch: Too many open files

[<ym...@jc...>]

Hi,

   +-From: Maximilien Renard <iix...@gm...> --
   |_Date: Mon, 16 Apr 2012 18:20:33 +0200 __________
   |

   |Saddly, as I started stress-testing the application, I've noticed
   |that after a certain number of file SFTP transfer, the library
   |"crashes" with the following message:

   |1: Caught an exception, leaving main loop due to SSH_MSG_DISCONNECT: 2
   |Could not create socket pairs: Too many open files
   |1: Disconnecting from 195.244.167.187 port 10004

It seems "socket pairs" means the Unix domain sockets for the communication
between "sshd" and "/usr/libexec/openssh/sftp-server", and it has been failed
to create them due to "Too many open files", as the message says.

At least, I guess that you can work around that error if the channel is
re-used without invoking "closeAndDisconnectSftpChannel()".

As for the problem, I have confirmed that the following chunk of code
will cause the reported error for sftp-server of OpenSSH 4.3p2,

      for(int i = 0; i< 1024; i++){
        try{
          ChannelSftp c = (ChannelSftp)session.openChannel("sftp");
          c.connect();
          c.disconnect();
        }
        catch(Exception e){
          System.out.println("i: "+i+" "+e);
          break;
        }
      }

However, I could not reproduce it for sftp-server of OpenSSH 5.3p1.

Which OpenSSH version are you using?  Frankly to say, I have not found
the problem in JSch yet, and have suspected that the older OpenSSH versions
may have the resource leaks in managing Unix sockets.


Sincerely,
--
Atsuhiko Yamanaka
JCraft,Inc.
1-14-20 HONCHO AOBA-KU,
SENDAI, MIYAGI 980-0014 Japan.
Tel +81-22-723-2150
Skype callto://jcraft/
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