[Casa-framework] Table lock under python

[Raymond Rusk]

On Tue, 26 Sep 2006, Lindsey Davis wrote:

> Hi,
> 
> I have forgotten all the issues associated with table locking, but I do
> remember that there were inconsistencies across the various tools. Some
> tools exposed lock / unlock methods to the user and others handled this
> internally. To the extent this matters now, it would be nice to harmonize
> interfaces across tools.
> 
> I also remember that there were problems with table cacheing / statics
> under the old protopipeline which probably no longer matter ?

Yes, I remember caching had something to do with it though that may have 
been specific to the ACS environment.  One could issue a table unlock, 
stop the process, physically delete tables from the filesystem and yet 
when tools were restarted in new processes they would still think that 
there was a locked table and refuse to generate another copy of the table, 
for instance.

> At any rate these kinds of problems do not seem to be troubling the
> heuristics group anymore.
> 
>                                                        Lindsey
> 
> 
> On Wed, 27 Sep 2006, Ger.VanDiepen at csiro.au wrote:
> 
> > Yes, that'll be the case. In Python everything is in one process, so
> > they share all locks. Of course, you do not need to quit python. You can
> > unlock a table.
> >
> > Ger
> >
> > -----Original Message-----
> > From: casa-framework-bounces at donar.cv.nrao.edu
> > [mailto:casa-framework-bounces at donar.cv.nrao.edu] On Behalf Of Kumar
> > Golap
> > Sent: Wednesday, 27 September 2006 8:13 AM
> > To: casa-framework at nrao.edu; Ger van Diepen
> > Subject: [Casa-framework] Table lock under python
> >
> > I've noticed an interesting locking issue... Maybe because now that
> > the python and the table or ms tool or any other too have the same
> > process id ...the lock on tables seems to hold even after quit the
> > tool.  So if i access the same table via the glish table tool say it
> > waits on the lock till I quit python.
> >
> > Kumar
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-- 
Dr. Raymond Rusk                                        Dr. Raymond Rusk
ALMA Software Engineer                           Ingenieur Logiciel ALMA
National Research Council Canada   Conseil national de recherches Canada
Herzberg Institute of Astrophysics   L'Institut Herzberg d'Astrophysique
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Raymond.Rusk at nrc-cnrc.gc.ca                  Raymond.Rusk at nrc-cnrc.gc.ca