Just to reinforce the point, could you give some general information of how much extra space is required to share a structure.

Eg. If a structure takes 10Kb as a non-shared entity, how much would it cost to share this with say 2 other threads (3 total)? Is it 30Kb, 40Kb, 50Kb extra?

Also, if you change a leaf (scalar) within that structure, how much slower is that than in a non-shared equivalent?

Finally, does the hit of updating the other copies of the modified value come

  • all at once in the context of the thread that makes the modification?
  • Or incrementally as the other sharing threads get a timeslice?
  • Or does the sharing thread have to defer until each of the other threads get a timeslice in order to update their copies?

    If the latter is the case, does the time the modifying thread waits for the others threads to update depend on the vagaries of the scheduler calling those threads (in competition with all other threads in the system), before the modifying thread can continue and unlock the modified scalar?

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    In reply to Re^2: "Auto" vivifying shared data structures by BrowserUk
    in thread "Auto" vivifying shared data structures by Dr. Mu

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