IZ2711: Jobs should be able to relinquish requested resources before completion

[dioktos]

[Imported from gridengine issuezilla ​http://gridengine.sunsource.net/issues/show_bug.cgi?id=2711]

        Issue #:      2711             Platform:     All           Reporter: dioktos (dioktos)
       Component:     gridengine          OS:        All
     Subcomponent:    clients          Version:      6.1u4            CC:    None defined
        Status:       NEW              Priority:     P3
      Resolution:                     Issue type:    ENHANCEMENT
                                   Target milestone: ---
      Assigned to:    roland (roland)
      QA Contact:     roland
          URL:
       * Summary:     Jobs should be able to relinquish requested resources before completion
   Status whiteboard:
      Attachments:

     Issue 2711 blocks:
   Votes for issue 2711:


   Opened: Sat Aug 30 05:54:00 -0700 2008 
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Consumable resources may no longer be needed by a job before it completes,
allowing another job to start. There should be a way for a task to relinquish a
resource it has requested.

   ------- Additional comments from dioktos Sat Aug 30 06:48:49 -0700 2008 -------
Perhaps a use case will help:

We have jobs (type 1) that spawn a number of other jobs (type 2) to do discrete
units of work. Type 2 jobs require draw full load from one CPU for some time,
then store some data in the database, which may take a significant amount of
time during which their CPU use is minimal. At that point, a CPU will be
effectively free to start another type 2. In other words, we need to have more
slots on a host than CPUs, but also need the initial allocation of type 2 jobs
not to exceed the number of CPUs on the host, until one of them goes into its
second phase. Thre doesn't seem to be a good way to do this with built in loads
or custom load sensors (since the initial allocation will simply fill all
slots), or the existing consumable resources (which can't be released).