[DRMAA-WG] misssing exceptions and thread safety
Andre Merzky
andre at merzky.net
Mon Mar 1 04:17:09 CST 2010
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.
> - "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
--
Nothing is ever easy.
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