Re: [GridSim-users] many simulations with only a Java process

[Marcos D. de A. <ma...@cs...>]

Hi,

technically speaking, it could be possible to run multiple simulation  
rounds in the same simulation process. SimJava's class Sim_system  
provides a feature that allows you to specify the termination  
condition, which I believe would allow you to specify the number of  
rounds:

/**
    * Specify a termination condition based on the confidence  
interval accuracy obtained for a default measure. This
    * condition is considered only once the transient period has  
elapsed. The accuracy is the ratio of the confidence
    * interval's halfwidth over the measure's total mean.
    * @param type                 The termination condition type.  
This must be set to <code>INTERVAL_ACCURACY</code>.
    * @param output_analysis_type The output analysis method to be  
used as a variance reduction technique
    * @param level                The confidence level for which the  
confidence interval will be calculated
    * @param accuracy             The accuracy that is required to  
satisfy the termination condition
    * @param entity               The name of the entity that  
contains the measure upon which the termination condition is based
    * @param measure              The <code>int</code> constant that  
represents the default measure upon which the termination
    *                             condition is based
    */
   public static void set_termination_condition(int type, int  
output_analysis_type, double level, double accuracy, String entity,  
int measure)

However, I have never tried this method before and I believe it will  
not work because for it to work, Sim_system makes a copy of the  
entities at the start of the simulation and puts them in a backup  
list. At each simulation round the entities are copied from the  
backup list back to the list of entities. The entities have to  
implement the Cloneable interface and I think that not all entities  
in GridSim implement Cloneable.

Alternatively, you can download the source code of SimJava2 and  
modify the Sim_system class to reset all static variables at the  
completion of the simulation. In this case, the code you have now  
would work. I believe that adding the following lines at the end of  
Sim_system.run() should suffice:

     incomplete = true;
     replications = null;
     total_time_elapsed = 0.0;
     total_transient_time = 0.0;
     min_batches = 10;
     max_batches = 20;
     run_data = null;
     trace_tags = null;
     default_trace = true;
     entity_trace = true;
     event_trace = true;

     entities = null;
     backup = null;
     future = null;
     deferred = null;
     clock = 0.0;
     running = false;
     onestopped = null;
     onecompleted = null;
     trcout = null;
     wait_predicates = null;

Regards,

Marcos



On 26/12/2008, at 11:58 AM, coa...@ti... wrote:

> Hello,
> I am an Italian student of the Faculty of "Ingegneria
> Informatica" of University of Catane, using Gridsim for my thesis.
> I'd
> like to know if there is a way to do many simulations with only one
> java process.
>
> For example: I want to check how my scheduling algorithm
> reacts to jobs of different length:short jobs and long jobs.
> To do this
> I want to make a simulation (SIMULATION_1) with a set of short  
> gridlets
> and another simulation (SIMULATION_2) with a set of long gridlets.
> I'd
> like to start these two simulations with only one Java process.
>
> I've
> tried a possible solution: I've set up two thread one for simulation_1
> and one for simulation_2. I've put GridSim.init(...) and GridSim.
> startGridSimulation() lines in the run() method of each of the two
> Threads.
> Thread_1 works -> OK
> Thread_2 doesn't work.
> In fact, when
> Thread_2 runs, all the Grid_sim entities doesn't execute their body()
> method.
>
> I am sure that Thread_2 starts only after that Thread_1 has
> Finished, because I've used the Thread.join() method and, in fact, on
> the screen appears:
>
> "
> ...
> Simulation completed.
> Initializing GridSim
> package
> ...
> "
>
> where "Simulation completed" refers to the simulation_1
> and "Initializing GridSim package" refers to simulation_2.
>
> What
> happens?
>
> What else can I do?
>
> Is there anybody who can help me,
> please?
> Thanks.
>
>
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Marcos Dias de Assuncao
Grid Computing and Distributed Systems (GRIDS) Laboratory
Department of Computer Science and Software Engineering
The University of Melbourne, Australia
Email: ma...@cs...

-------------
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