GFD.133 has a good statement in the description of the control() function: "This routine SHALL return once the action has been acknowledged by the DRM system, but does not necessarily wait until the action has been completed." This underlines Dan's argumentation, the point of synchronization resp. atomicity is the DRMS itself. It was no problem in DRMAAv1, since we carefully avoided to demand any kind of state saving in the library. This changed with the new persistency features. We discussed possible new race conditions in Hamburg, but couldn't find anything unsolvable. The new concept demands only the storage of identifiers so far - for sessions (if supported by the DRM) and jobs. The state still must be retrieved from the DRM on every usage.
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 you provide a link for this text ? I cannot find it. It also makes no real sense - job state NEVER EVER should be persisted in the DRMAA library itself.
*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?
It cannot, and it is no problem. A "test-and-set" semantic of the library is not expected here. The DRMS should tell the library that suspend() is not allowed with the current state. Or in other words - we expect the job control functions of the DRM system to act (more or less) like the DRMAA equivalents. So far, this worked out. Best, Peter.