Hi, Yes, your suggestion also works, just as my hack did, by forcing the allocation of a pty. Unfortunately, I am concerned of the performance and resource ramifications in my application, as there could be hundreds, or potentially thousands of these sessions.
Based on your suggestion, I added the following code: // HACK! This is to cause the SSHD not to buffer data for better performance com.jcraft.jsch.ChannelExec hackChannel = ( com.jcraft.jsch.ChannelExec ) dataSession.getSession( ).openChannel( "exec" ); hackChannel.setPty( true ); // Assign a Pseudo TTY to our Session to improve latency for small packets from SSHD hackChannel.connect( ); hackChannel.disconnect( ); After this code executes, any reverse forwards over this Session are high performance (no latency). I am also worried about a timing issue by disconnecting the ChannelExec immediately after connecting in a high-volume scenario. What do you think? Thanks, - Scott On 5/19/2011 10:15 PM, Atsuhiko Yamanaka wrote: > Hi, > > Thank you for your interesting feedback, > > +-From: "B. Scott Smith"<sc...@smithdomain.com> -- > |_Date: Thu, 19 May 2011 12:12:18 -0500 ___________ > | > |After investigating this issue, I discovered that the performance was > |good with the native SSH client because it was allocating a pseudo > |terminal (pty) to display the remote command shell. When I instructed > |the SSH client NOT to allocate a pty (ssh -N -R5900:localhost:5900 ...), > |I was able to duplicate the same poor performance I saw with JSch. > |Apparently, if there is no pty assigned to the remote session, the SSH > |server will buffer and "chunk" the data over all reverse forwards on > |that session. > > Is it needed to keep running pty during remote port forwarding session or > is it enough to establish and disconnect pty before requesting port > forwarding? > If the later is enough, how about > ChannelExec#setPty(true) > with simple remote command? > > > Sincerely, > -- > Atsuhiko Yamanaka > JCraft,Inc. > 1-14-20 HONCHO AOBA-KU, > SENDAI, MIYAGI 980-0014 Japan. > Tel +81-22-723-2150 > +1-415-578-3454 > Skype callto://jcraft/ > Twitter: http://twitter.com/ymnk > Facebook: http://facebook.com/aymnk ------------------------------------------------------------------------------ Simplify data backup and recovery for your virtual environment with vRanger. Installation's a snap, and flexible recovery options mean your data is safe, secure and there when you need it. Data protection magic? Nope - It's vRanger. Get your free trial download today. http://p.sf.net/sfu/quest-sfdev2dev _______________________________________________ JSch-users mailing list JSch-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jsch-users
