flag whether or not a program has been called by createTask

I run certain jobs either as standalone jobs, or in parallel, for example called by createTask. Is there some way to distinguish between these cases? obviously I could use brute force, use dbstack and related tools and check if the calling line had the word createTask in it, but I'd much prefer to do something more general/elegant. Since one can interact with programs in the former case, but not the latter, there must be something matlab knows that I can tap into...

Thanks very much for any help!

Leo

Answer 1

[Edric Ellis]

One simple way is to check the return of getCurrentTask. This will always return empty in a desktop MATLAB session, and a parallel.Task object when running on a worker.

[Leo Simon]

Thanks, just what I needed

[Leo Simon]

I accepted this answer but at the time I must have been running version R14b, with 15a it returns a warning

>> isempty(getCurrentTask)
Warning: Unexpected error trying to obtain the current task. 
> In getCurrentTask (line 24) 

Warning from getCurrentTask (line 24)
    warning(message('parallel:cluster:GetCurrentTaskFailed'));

I can of course suppress the warning, but if this is the only/best way to check if I'm in parallel, then it's disappointing.

[Edric Ellis]

Hm, I don't see the warning in R2015a. What are your precise reproduction steps to get that? Here's what I did, after opening a (local) parallel pool:

>> getCurrentTask
ans =
     []
>> spmd, getCurrentTask, end
Lab 1: 
  ans = 
   Task with properties: 

                       ID: 1
                    State: running
                 Function: @distcomp.nop
                   Parent: Job 7
                StartTime: Mon Jan 11 12:43:28 GMT 2016
         Running Duration: 0 days 0h 0m 60s

          ErrorIdentifier: 
             ErrorMessage: 
>>