[daip] AIPS 1: TASK ACTIVE problem

[Eric Greisen]

Philip Lah wrote:
> Hello Eric,
> 
>   unfortunately I do not have much I can add to give a more complete 
> description of the problem.  I am using perl scripts to interface with 
> AIPS for my data reduction.  For some reason on the new machine I now 
> occasionally get the TASK ACTIVE halting my task and stopping my script. 
> Years ago I did look at using DOWAIT but I discarded it as an option 
> because it did not give the result I wanted with my scripts.
> 
>   From your email I now have a suspiscion about what may be going wrong. 
> In the perl script that halted prematuraly last night I have multiple 
> FITTP commands that run one after another outputting the 25 facets of my 
> continuum image.  I am guessing the for one of the runs the 
> FITTP1.$nnnnn for the precious run in the /tmp dir had not been removed 
> before the next FTTP started, so AIPS decided to halt with the TASK 
> ACTIVE error.  This does not always happen as I ran the same script 
> today with no trouble.  I suspect that the machine was under higher 
> read/write pressure when the problem occured hence the delay in removing 
> the old FITTP1.$nnnnn.  I am not sure how to stop this problem from 
> happening again.  Perhaps I should have my scripts check for the 
> existance of the FITTP1.$nnnnn before deciding to continue.

Actually you should probably set DOWAIT true or before running a task 
give the command
      WAIT <task>
where <task> is the task name.  The WAIT will finish immediately if the 
task is not running and will wait for it to finish otherwise.  You are
running a script depending on race conditions and that is unwise.  The
DOWAIT true does allow the task to decide that it has failed and then 
notify AIPS while otherwise all the task knows is that it started up okay.

Eric Greisen