LIGHTWEIGHT GRID MANAGER TUTORIAL

Troubleshooting

The section gives some help with common problems that can occur when running the Lightweight Grid.

Cannot Connect to the Server

Suppose that you set up the Lightweight Grid on a server. Then, you launch your master copy of Mathematica on a different machine, and open Parallel Kernel Configuration from the Evaluation menu. You locate your server and set it up to launch two kernels as shown below.

1.gif

Then you try to connect to these two parallel kernels, but you see error messages. Here is an example.

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Out[1]=

This suggests that the published name of the machines, TWJDesktop1, is not visible across your network. You could confirm this by using a web browser on the machine that runs the master Mathematica. If the browser cannot connect to the URL shown in the error message, http://TWJDesktop1.example.com in this example, this indicates there is a network host naming issue.

The solution is either to fix your network so that you can find machines by name, or to change the ContactURL server configuration parameter, for example using the IP number of the server.

Cannot Connect to the Link

Suppose that you set up the Lightweight Grid on a server. Then, you launch your master Mathematica on a different machine, and open Parallel Kernel Configuration from the Evaluation menu. You locate your server and set it up to launch two kernels as shown below.

4.gif

Then you try to connect to these two parallel kernels, but after a long time you see error messages. Here is an example.

This suggests that the server was found, and responded with a link, but that the link could not be used. The clue here is that the name of the link, 192.168.70.1, is a private network name. This name has been picked by the link system called by the Lightweight Grid, but is a name not visible outside of this machine. You can inspect the link further by using manual launching from the web interface.

The solution is to change the configuration of your system, or to use the LinkHost kernel configuration parameter to set the IP number for the link.

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