![]() Unfortunately, callbacks sometimes need to perform a lengthy computation or update (for example, updating an Excel file). Users may lose patience with long callback execution. The quicker the callback, the more responsive the GUI. Matlab timers are certainly under-appreciated for their performance usefulness.Īs a related usage, GUI callbacks should be designed to be as short as possible. This relates to the interesting topics of perceived performance and lazy/delayed evaluation. During this time the user can peruse the GUI, getting a feeling of improved responsiveness compared to a situation of having to wait all those long seconds for the GUI to initially load. I often employ Matlab timers in GUIs: the initial GUI is presented to the user immediately, and then a timer is used to load data from I/O, something which could take long seconds. our earlier examples is that the timer code is not run in parallel to the fft post-processing, but rather 2 seconds later, when MT is hopefully idle. Start (Timer ( 'StartDelay', 2, 'TimerFcn',timerFcn ) ) % start after 2secĭata = fft (data ) % post-processing (timer I/O will run later!) First we define the timer’s callback function, using pure M-code (this is the Matlab equivalent of the run() method in the previous examples):ĭata = rand (5e6, 1 ) % pre-processing (5M elements, ~40MB) Here is an implementation of our asynchronous I/O example, this time using Matlab timers. The purpose of multi-threading would be to offload the I/O onto a separate thread, so that the Matlab computation can continue in parallel without needing to wait for the slow I/O. I continue using last weeks’ example, where we compute some data, save it to file on a relatively slow USB/network disk, and then proceed with another calculation. But in fact, the ability to schedule a Matlab processing task for later (non-serial) invocation, could be very handy, if we can time it so that the timer callback is triggered when the application is idle, for example, waiting for user input, following complex GUI update, or during late hours of the night. This may seem on the face of it to be unhelpful. So, while a timer callback executes, no other M-code can run. ![]() The reason for this is that all M-code, including timer callback code, is executed by Matlab’s interpreter on a single processing thread (MT). Matlab timers, on the other hand, only enable the second option, of running code asynchronously. Net threads can improve performance by both of these manners. By allowing code to run asynchronously, rather than in serial mannerĬ++, Java and.By allowing code to run in parallel, on different CPUs or cores.Multithreading helps application performance in two related but distinct ways: As we shall see below, these are not “real” multi-threading alternatives, but they can indeed be important in certain use-cases. Today I conclude the mini-series by examining two other alternatives, timer objects and process-spawning. In the past weeks, I explained how we can start asynchronous threads to run in parallel to the main Matlab processing using Java, Dot-Net and C++ POSIX threads.
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