How to stop a parsim (parallel Simulink simulation) run from a worker when a certain condition occurs in R2022b?

In the context of conducting multiple parallel simulations using MATLAB's parsim function in R2022b, I am looking for a method to dynamically interrupt and halt the entire batch of simulations based on specific runtime conditions. Specifically, I need to stop the parallel execution when one of the simulations meets a certain criterion, such as reaching a specific value or condition within its simulation data. How can I implement a mechanism in MATLAB R2022b that monitors the simulations' progress and appropriately terminates the parallel pool when this predefined condition occurs, ensuring an efficient and controlled simulation environment?

Answer 1

[MathWorks Support Team]

In MATLAB R2022b, you can halt a parallel Simulink simulation (parsim) from a worker based on specific conditions by leveraging the post-simulation function callback (setPostSimFcn) and a value store callback (ValueStore) associated with a parallel pool. This method allows for dynamic control over the simulation process, enabling the termination of the parallel pool when predefined conditions are met. Below is a step-by-step guide on how to implement this functionality:

Step 1: Prepare the Simulations

First, initialize your simulations with the necessary parameters and the post-simulation function. This function will check the condition to decide whether to stop the simulations.

mdl = 'simpleMdl';
numSims = 100;
simIn(1:numSims) = Simulink.SimulationInput(mdl);
for idxSim = 1:numSims
    simIn(idxSim) = simIn(idxSim).setVariable('A', idxSim);
    simIn(idxSim) = simIn(idxSim).setPostSimFcn(@myPostSimFcn);
    simIn(idxSim).UserString = string(idxSim);
end

Step 2: Initialize Parallel Pool and Value Store

Check if a parallel pool exists; if not, create one and initialize a ValueStore for it. The ValueStore is used to trigger the shutdown based on the simulation index.

if isempty(gcp("nocreate"))
    pool = parpool('Processes');
    store = pool.ValueStore;
    store.KeyUpdatedFcn = @shutdownParpool;
end

Step 3: Run the Simulations

Execute the parallel simulations with the parsim command, ensuring that the simulations continue even if errors occur.

out = parsim(simIn, "StopOnError", "off");

Step 4: Define the Post-Simulation Function

The post-simulation function evaluates after each simulation. If the condition (e.g., simulation index greater than 20) is met, the function updates the ValueStore, triggering its callback to stop the parallel pool.

function simOut = myPostSimFcn(simOut)
    idxSim = simOut.SimulationMetadata.UserString;
    shutdownParpool = double(idxSim) > 20;
    if shutdownParpool
        store = getCurrentValueStore();
        store(double(idxSim)) = idxSim;
    end
end

Step 5: Define the Value Store Callback Function

This function acts upon the ValueStore update. It shuts down the parallel pool when triggered by the post-simulation function.

function shutdownParpool(store, key)
    pool = gcp("nocreate");
    if ~isempty(pool)
        disp("Simulation number " + key + " is causing the shutdown of the parpool.")
        delete(pool);
    end
end