Interactive are all tasks that require user dialogue and can not work in batch mode. All graphical applications (Mathematica, Maple, etc.) are classified as such, as well as some of the command line applications whose input and output can not be redirected.

Launching interactive tasks

Interactive tasks are started with the command qsh -l h_rt = hh: mm: ss, where hh: mm: ss is the time we expect as the maximum session duration. Other resources may be requested with the suggested resource specifiers. After submitting this command, the resource allocation system attempts to satisfy within a few seconds the desire for resources and, when successful, runs the xterm graphics terminal on one of the free processors. In case of failure, an error message is received and the interactive session is denied. This happens if there are no free processors for interactive work at present or if the requested resources exceed the available ones. For proper startup of the graphical terminal, you should have a working X server and propperly set $ DISPLAY environment variable. The latter happens automatically if you use tunneling X11 through the SSH session to the cluster. For more details, see the graphic apps page.

Parallel interactive tasks

It is possible to run multithreaded and / or multiprocessing interactive tasks. For the purpose of the qsh command. The parallel enviroment should be specified to use ithreads with the appropriate number of slots, for example:

qsh -l h_rt=1:0:0 -pe ithreads 4

This command declares four processors for a multi-threaded application (Java, OpenMP, or other mechanism). After starting the interactive session, you should indicate to the applications you are working with that they should use 4 threads. The very mechanisms by which this is done are specific to the various applications. One should find the mechanism to determine the level of competition of the applications you work with.