start

Start collecting parallel pool activity monitoring data

Since R2025a

Syntax

start(monitor)

Description

start(monitor) starts collecting pool activity monitoring data using the ActivityMonitor object, monitor.

Use the start function to restart monitoring pool activity with an ActivityMonitor object that has previously stopped monitoring activity.

If monitor is already monitoring pool activity, the software discards any results collected.

Examples

Start Collecting Pool Activity Monitoring Data

Create a parallel pool using the cluster profile, myCluster.

pool = parpool("myCluster",4);

Starting parallel pool (parpool) using the 'myCluster' profile ...
Connected to parallel pool with 4 workers.

Create an ActivityMonitor object to collect monitoring data for the pool but do not start collecting data immediately.

monitor = parallel.pool.ActivityMonitor(pool,Start=false);

Create some large data on the client, then build a Constant object, C, transferring the data to the pool only once.

data = rand(1000);
C = parallel.pool.Constant(data);

Start collecting pool monitoring data using the ActivityMonitor object, monitor.

start(monitor)

Run multiple parfor-loops accessing the Constant object, C. For efficiency, preallocate the results array.

x = eye(5);
for ii = 1:5
    parfor jj = 1:5
        x(ii,jj) = C.Value(ii,jj);
    end
end

Stop the activity monitor and retrieve the monitoring results collected during the execution of the parfor-loops.

monitoringResults = stop(monitor);

Restart Monitoring Data Collection

Create an ActivityMonitor object to start collecting pool monitoring data. With default settings, parallel.pool.ActivityMonitor automatically starts an interactive parallel pool using the default profile if one does not exist.

monitor = parallel.pool.ActivityMonitor;

Starting parallel pool (parpool) using the 'Processes' profile ...
Connected to parallel pool with 6 workers.

Submit multiple parfeval computations to compute magic squares. Wait for all tasks to complete.

f(1:100) = parallel.Future;
for idx = 1:100
    f(idx) = parfeval(@magic,1,idx);
end
wait(f);

Use the stop function to stop collecting monitoring data and retrieve the monitoring results.

monitoringResults = stop(monitor);

To restart collecting monitoring data, use the start function.

start(monitor);

Input Arguments

monitor — Pool activity monitor

ActivityMonitor object

Pool activity monitor, specified as an ActivityMonitor object.

Example: monitor = parallel.pool.ActivityMonitor

Version History

Introduced in R2025a