On 03/01/10 11:17, Andre Merzky wrote:

Quoting [Daniel Gruber] (Mar 01 2010):

   Hi,
   while scanning the wiki I found following:
   The Job object methods should throw following exceptions:
   - "JobAlreadySuspendedException" from suspend method when
     job is already suspended. The DRMAA implementation have
     to make sure that suspend job is just called once. It is not enough
     for the DRMAA implementation to rely on own state, it should
     check the state automatically in order to avoid problems when
     the state is set outside of DRMAA. Should DRMAA deal with
     such cases?


*Can* DRMAA deal with such cases?  These are two operations which
are usually not atomic (1: check for state, 2: suspend) - so how can
a DRMAA client side library ensure that the remote state does not
change between these two calls, e.g. due to a 3rd part API call?

I guess it's ok to throw when the backend replies with that error
(job already suspended) - but requiring the DRMAA implementation to
ensure atomicity is most likely futile.

my $0.02, Andre.

You're right - atomicity seems not to be possible.

Another important thing to know would be if all DRMs are throwing such an exception
or are there any which are silently ignore second request and telling again that it
is suspended (suspend is idempotent). Do we have than a problem with the spec saying
that there is an Exception but on some implementations there will be never throw one?
We should make the exception optional if so.

Cheers

Daniel

   - "JobNotSuspendedException" from the resume method (like above).
   - "JobTerminatedException" when calling a method on a job
      when the job is already terminated.
      This is for "suspend" "resume" "hold" "release" "terminate"
   "waitStarted"
   Obvious synchronization problems:
   - accessing an already "deleted" JobTemplate: here that same as for a
   destroyed Session should apply (InvalidJobTemplateException)
   - accessing a job template while "deleting" (running a job or accessing
   otherwise): here that same as for a destroyed Session should apply
   (InvalidJobTemplateException)
   - write access for the job templates must be synchronized by the DRMAA
   implementation
   - Is there a need to make the invalid state of a JobTemplate (that is
   when a JobSession
     has been closed) as an accessible field or should every problem
   covered by the
    "InvalidJobTemplateException"?
   Regards
   Daniel