close

Close pollable data queue

Since R2025a

Syntax

close(pollablequeue)

Description

close(pollablequeue) closes the parallel.pool.PollableDataQueue object specified by pollablequeue. You can no longer send data to the queue using the send function.

Examples

Stop Worker Sending Data From the Background

Define a function, sendMessages, that sends messages to a pollable data queue. It sends five messages, simulating work by pausing for one second between sending each message.

function sendMessages(queue)
    for idx = 1:5
        send(queue,sprintf("Message %d from worker",idx));
        pause(1);
    end
end

Create a PollableDataQueue object, and use parfeval to execute the sendMessages function in the background. Pause briefly to allow the worker to send some messages.

queue = parallel.pool.PollableDataQueue;
f = parfeval(backgroundPool,@sendMessages,0,queue);
pause(2);

To stop the background from sending any more data to the queue, close the PollableDataQueue object.

close(queue);

Wait for the parfeval computation to complete. Query the Error property of future object f to verify that an error occurred due to an attempt to send messages to the closed queue.

wait(f);
f.Error.message

ans = 
'Failed to send data because the DataQueue has been closed.'

Input Arguments

pollablequeue — Pollable data queue

PollableDataQueue object

Pollable data queue, specified as a PollableDataQueue object.

After you close a PollableDataQueue object, you can no longer send data to the queue. Any attempt to send data to the queue results in an error. You can continue to poll the queue for data. You cannot reopen a closed queue.

Example: p = parallel.pool.PollableDataQueue;

Extended Capabilities

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

Version History

Introduced in R2025a