[DRMAA-WG] Meeting Minutes from August 4th

[Peter Tröger]

- July 28th meeting minutes: accepted

- Peter: Proposal to solve synchronization issue raised in the last  
meeting
    - wait() / waitAny() is only for getting notified about some  
transition event
    - new dedicated function to fetch the history of state changes
    - Roger: If waitAny() then returns for one job, what about the  
transitions of other jobs ?
    - Roger: Proposal: Return job(s) that changed state since a given  
point in time

- Dan: In general, three approaches for synchronization capability
    - 1) State change notification without history keeping in-between  
the wait() / waitAny() calls -> sounds useless
    - Waiting for a state to happen (similar to old wait() if we  
include reaping)
    - State change event callback functionality in the API

- Roger/Dan: There is no real use case for long-ago historical state  
changes, let's just care about last transition and current state

- Agreement that event notification (as precondition for callbacks) is  
not supported by majority of DRM systems -> wait() solution must rely  
on some kind of pull model

- To be useful, wait() functions have to wait on transitions, since  
current state querying is covered in another part of the API
    - Wait() functions should save from fetching job states in a loop

- Dan: Difference between waiting for any job state change  
(information dropping ok) vs. waiting for state change of one  
particular job
    - Roger:  Concern about waitAny() not returning the current state  
of a job which transitioned between waitAny() invocations.

- Need to go back to original use cases:
    - Waiting for job start
    - Writing qstat with DRMAA
    - Writing qmon with DRMAA
    - Waiting for job end (DRMAA1)
    - -> Discussion on mailing list

- Roger: Current waitAny() specification allows caller to indicate the  
jobStates of interest
    - Need to discuss if/how this effects a subsequent call requesting  
different jobStates
    - Is waitAny concerned with the most recent transition for a job  
after the previous waitAny(), or the previous waitAny in which the  
jobState was returned.