XMM-Newton Science Analysis System: User Guide

3.6 Task control

It is possible to kill a running task from the "Task" menu. This is useful if a long task is accidentally started with the wrong parameters or if a task appears to "hang" for some reason. Killing a task may, of course, result in the output files being truncated or corrupted.

For interactive processing, it is normal to run one task at a time. However, once a task has started, a parameter dialog can be opened to configure the parameters in preparation for running the next task. By pressing the "Run" button before the previous task has finished, one gets the option of running the task immediately or queuing it for later execution:

• Immediate execution is appropriate if the tasks make use of separate files, so that they may be run in parallel.

• Queuing is appropriate to create a process chain, where each task makes use of the output from the previous task.

The next queued task is started automatically when all current running tasks have finished. Tasks are logged when they are started.

When a task is started, or queued for later execution, the parameter values are saved along with the task. Consequently, editing the parameters and queuing a second instance of a task will not affect the parameters of a task that is already running or queued.

The current implementation has the following limitations:

• Changing preferences which affect a task, such as the setting of ODF/CCF directories, will affect queued tasks which have not yet started.

• The "kill" command on the "Task" menu kills the last task started. It is only possible to kill an earlier task by killing all later tasks.

• The "kill" command cannot be used to remove a queued task which has not yet started.

• If a queued task fails, the remaining tasks in the queue will still be executed.