[daip] "parallel" AIPS issue

[Joseph Lazio]

Hi, 

I'm trying to use AIPS in a simple (stupid?) parallelization mode,
which is leading to paralyzation.

AIPS 31DEC08

Background:

I have a bunch of FITS u-v data files.  I'd like to read them into
AIPS (FITLD), image them (IMAGR), and do some simple statistics
(IMSTAT).  I've written a little script to do so, and in a variety of
tests, it has proven robust.


Parallelization:

I have a driver script that sets up some variables, then spawns
multiple instances of AIPS.  Each instance of AIPS uses a different
user number.  For example, 
day 1 -> AIPS id 10001
day 2 -> AIPS id 10002
day 3 -> AIPS id 10003
...

If I do this by hand, using command-line editing, everything works,
e.g., 

% run-aips.sh  10001 & <CR>
<up-arrow>
% run-aips.sh  10002 & <CR>
<up-arrow>
% run-aips.sh  10003 & <CR>
<up-arrow>
...


However, if I use the OS to spawn the runs "simultaneously," all kinds
of apparently random errors start appearing.  AIPS will declare 'TASK
ACTIVE' for FITLD, even though for the AIPS id in question, it isn't.
Occasionally in the output log, I see errors in FTLIN, which are
reported from GTPARM.



My conclusion is that, somehow, when I use the OS to spawn the runs
simultaneously, the various instances of AIPS are attempting to access 
the TD* accounting file simultaneously and having access issues.  If
I'm correct, this appears to be a fundamental design issue of AIPS,
and not something that could be changed simply.

Agree?  Comments?

-- Joe

-- 
Joseph Lazio, Ph.D.           	    voice:  +1-202-404-6329  
Naval Research Laboratory     	    fax:    +1-202-404-8894 
4555 Overlook Ave. SW         	    Joseph.Lazio at nrl.navy.mil
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