Multi threading with Model View framework?

[CAD_coding]

Hi,
Please forgive me because this is my first application in GUI as such & after reading some suggestions on this forum & the articles I have now understood the concept of Model/View framework.
But I am unable to implement it in my multi threaded application because I am unable to decide which classes are good for multi threading. Let me tell something about my application:

Basically I am storing a 2D array of double variables for performing scientific calculations in my application. I was previously using QTableWidget for displaying this data to the user. It was fine till array size was 1000x1000 & single threaded. But when I multi threaded the initialisation of data from reading a file, it gave very bad performance. Hence moving to Model/View framework.
My usage is:

Opening the file in each thread, reading data from it & setting it to the GUI. Each thread has a pre-decided set of rows which it initialises. (EX: for 1000x1000, if there are say 4 threads then thread 1 will initialise 1-250, thread 2 will initialise 251 - 500, & so on). So far I am setting the data to a double array along with the table. If I comment out the QTableWidget code then I get a tremendous performance boost. This means that my existing multi threaded code is good & the problem is only when I set the data to QTableWidget & not the double array.

Any suggestions on how I should implement the Model/View framework?
Thank You.

[SGaist]

Hi,

You should look into making your own model (QStandardItemModel or QTableModel) and use a QTableView. You are currently loading what seems to be a lot of data then duplicate it in your QTableWidget which will impact on your performance.

Hope it helps

[CAD_coding]

Hi SGaist,
Can I add data to QStandardItemModel from multiple threads simultaneously?
If yes then is it fine if I keep a pointer to the model in each thread & then add data to it from each thread?

Also I think the QTableView should be in the GUI thread, but what about the QStandardItemModel? Is it ok to keep it in different thread without affecting performance?

[JKSH]

Hi,

All QObjects (including QStandardItemModel) are not thread-safe, so you cannot write to them simultaneously from multiple threads. Each object must only be accessed from one thread.

Keep your QStandardItemModel in the GUI thread, and implement a slot to update its data. When each thread has finished initializing the data, emit a signal to tell the slot to update the QStandardItemModel.