August 2007


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Sean Luke <[log in to unmask]>
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MASON Multiagent Simulation Toolkit <[log in to unmask]>
Thu, 9 Aug 2007 18:42:38 -0400
text/plain (39 lines)
The reason for this is fairly simple: the parallel sequence's step  
call (in which you're trying to make these calls) is made from an
outer call to Schedule.step(). This outer call is synchronized on
the schedule. However, also state.schedule.time() and state.getSteps
() are also synchronized on the schedule, and your inner parallel
sequence threads thus don't have access to it until the main thread
exits from Schedule.step().

This is clearly a stupid error in MASON's schedule: let me Ponder
Deeply upon it.


On Aug 9, 2007, at 6:27 PM, Maciej M. Latek wrote:

> Dear MASON team,
> I have a number of agents being stepped by ParallelSeqence facility.
> For most of the time it runs smoothly. Nevertheless, I got into a
> minor problem when trying to query the schedule for time: any
> reference to state.schedule.time() or getSteps() causes a deadlock. I
> have tried putting it as a synchronized call with locking on schedule
> and simulation, I tried adding a synchronized function to SimState
> that would return me that information, always with the same result.
> Is it possible to access schedule when agent is stepped of the
> ParallelSequence at all without causing deadlocks? Or is
> ParallelSequence locking the schedule?
> Above mentioned issue is more of theoretical significance for me: as I
> need just coarse approximation of the number of steps from schedule, I
> update agents with this information just before the ParallelSequence
> is stepped.and avoid querying the schedule. I would love to know the
> answer for potential future developments though.
> Regards
> Maciek