[Halld-offline] zero field

[Matthew Shepherd]

With bits and pieces from 3 different people,  I think 
I've figured this out...  gggrrrrrr!

Mike Staib suggested my log seemed to indicate my field doesn't have
enough z points.

It seems like jana is using JANA_RESOURCE_DIR to cache fields.  (I got
this from Paul.. I've never set this, but grep and reading jana source 
tells me it is set by default to /tmp/username/resources.)

If I go to that directory and delete it and rerun bfiled2root, I get 
a full field.

What happened?  Here's my theory:

I ran a job and that job chose to download the field.  This
is the first time consuming thing that happens in a job.  If, 
during the field download you kill the job with ctrl-c then 
you are left with a partial field.
(I tested this out and was able to repeat it.)

I must have been unlucky and hit ctrl-c on the job that
tried to download the field.  Note this is normal for must users.
It is easy to execute a command accidentally or realize just
after you press return that you didn't specify all the arguments
that you wanted.

This is a really nasty behavior because every subsequent job
then just reads this partial field and never prints any message
or error.

Can we put some sort of check in the field?  Write the number
of points in the file first.  And then on read back when there
isn't than many points abort with an error.

nasty nasty nasty... that cost Paul and me a ton of time
this week

Matt

---------------------------------------------------------------------
Matthew Shepherd, Associate Professor
Department of Physics, Indiana University, Swain West 265
727 East Third Street, Bloomington, IN 47405

Office Phone:  +1 812 856 5808

On Jul 18, 2014, at 7:18 AM, David Lawrence <davidl at jlab.org> wrote:

> 
> Hi Matt,
> 
>   The output looks right. What happens if you run the bfield2root utility? This should
> be built as part of the default sim-recon build. (Source is in $HALLD_HOME/src/programs/Utilities/bfield2root)
> 
> Draw the field map in ROOT using:
> 
> >bfield2root
> >root bfield.root
> root [1] Bz_vs_r_vs_z->Draw("colz")
> 
> Also, how are you checking that the field map is returning zeros?
> 
> Regards,
> -David
> 
> On Jul 17, 2014, at 9:49 PM, Matthew Shepherd <mashephe at indiana.edu> wrote:
> 
>> 
>> Hi all,
>> 
>> Paul and I have been trying to understand why I cannot
>> get the example analysis software working and we seem
>> to have traced the problem down to the fact that the 
>> magnetic field map is returning a zero field.
>> 
>> Does anyone know how to debug this?  The startup
>> of the job suggests all is OK (I think):
>> 
>> JANA >>URL: sqlite:////home/s4/mashephe/gluex/ccdb.sqlite
>> JANA >>context: default
>> JANA >>Reading Magnetic field map from Magnets/Solenoid/solenoid_1350_poisson_20
>> 130925 ...
>> Nx=251 Ny=1 Nz=43 )  at 0x7f46720a0ce0
>> Fine-mesh evio file does not exist.
>> Constructing the fine-mesh B-field map...
>> rmin: 0 rmax: 88.5 dr: 0.1 zmin: 0 zmax: 600 dz: 0.1vg.: 0.0Hz)     
>> Number of points in z = 6000
>> Number of points in r = 885
>> JANA >>10599 entries found (Created Magnetic field map of type DMagneticFieldMap
>> 
>> I'm using:
>> 
>> sim-recon-2014-06-30
>> ccdb_1.02
>> hdds-2.1
>> jana_0.7.1p3
>> 
>> and a ccdb.sqlite file from July 14 (copied from Mark's web page link that day).  I've also
>> tried the ccdb.sqlite file from dc2 conditions.
>> 
>> Matt
>> 
>> 
>> ---------------------------------------------------------------------
>> Matthew Shepherd, Associate Professor
>> Department of Physics, Indiana University, Swain West 265
>> 727 East Third Street, Bloomington, IN 47405
>> 
>> Office Phone:  +1 812 856 5808
>> 
>> 
>> _______________________________________________
>> Halld-offline mailing list
>> Halld-offline at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/halld-offline
>