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DPS921/Web Worker API

34 bytes added, 20:38, 4 December 2020
Dedicated Worker
Now running the Sobel filter on a separate thread allows us to continue interacting with the UI but, the execution time slightly increased. This is because we have to instantiate the worker, which takes time and resources. Luckily, we can drastically improve the Sobel filtering process by breaking the image down into horizontal chunks. We do this by getting the height and dividing by the number of processors allowed by the browser, which is obtained using the Windows API (''window.navigator.hardwareConcurrency''). Once we chunk the image, we can create ''n'' number of worker objects based on the hardware concurrency set by the browser and post the chunk of data to them with their ID (''index''). When a worker is finished running, it will send a response using the ''onmesasge'' event handler, so we can assign a function to be executed when the event is triggered. In the file, we passed into the web worker constructor, we refer to the global scope using self and call the ''onmessage'' event handler. This event handler receives the posted data we sent from dedicated.js and initiates the Sobel filtering. Once the filtering is done, the data is posted back by referring to self.
INSERT GRAPH OF THE DATA[[File:Sobel Filtering Execution Time Per Processor.PNG]] 
Here are the results we got from running the Sobel filter on 10 processors. As we utilize more web workers, the faster the filter is applied to the image.

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