Slowness opening ENVI interface while connected remotely using SSH

 

Problem:

Customer can encounter a slowness while opening the ENVI interface while working on a remote connection.

Discussion:

After discussing with developers, it seems that performance delays in remotely displaying a GUI via X/ssh is not unexpected, as there are a number of factors that reside on both the remote and local machines that can contribute to this delay. Also, because the ENVI 5 GUI is particularly complex (far more complex than the ENVI Classic menu bar), realization of this GUI seems to be particularly susceptible to this issue.

Other complex GUI and heavy graphical applications from other vendors can also be susceptible to similar performance issues when used over a remote connection.

Proposed solutions and workarounds:

However, there may be ways to improve the startup time for ENVI in this situation. Here are some possibilities:

1.) For ssh X11 forwarding, if permitted, using Trusted X11Forwarding  (using "ssh -Y" rather than "ssh -X") might reduce communication times since it avoids the extra restrictions imposed by the X11 SECURITY extension.

2.) Additionally for ssh, if the network bandwidth between the remote and local machine is particularly narrow or taxed, perhaps compressing the ssh communications (using -C switch) could help. For example:

   ssh -YC ...

3.) Another idea might be to avoid the overhead of X11forwarding (which causes X communication to be redirected to a proxy X forwarding server on the Linux machine, which then communicates with the X server running on the XP machine) altogether, by using direct TCP/IP port communication, such that the DISPLAY environment variable on the Linux machine must be explicitly defined to point to the display system’s X server Display window setting, for example (from a Bash shell):

   export DISPLAY=mywinxp-machinename-or-ip:0.0

and then starting ssh without X11 forwarding:

   ssh -x ...

4.) Another idea might be to use remote desktop utility connection (like RealVNC) instead of a remote X11 display.  In this case, a virtual X server is running on Linux and only images of the Linux desktop are displayed to the XP system(rather than local X server display rendering of widgets, and high volumes of event communications between the local X server system and the remote ENVI/IDL host system).

5.) Lack of OpenGL rendering capability may also affect remote ENVI rendering performance for aspects that may otherwise take advantage of IDL object graphics OpenGL rendering acceleration. Here is a link to another help article that discusses this related topic:

http://harrisgeospatial.com/Support/SelfHelpTools/HelpArticles/HelpArticles-Detail/TabId/2718/ArtMID/10220/ArticleID/18142/5312.aspx

Finally, if it can be helpful, here is a web page on the Lawrence Berkeley National Lab web site that discusses various approaches to accelerating Remote X Performance of GUI applications:

  http://vis.lbl.gov/Events/SC08/RemoteX/index.html

Reviewed on 04/02/2014 by JU