Maya gets closed with giving an error

[Anonymous]

I am creating a gui using maya python maya.cmds  . When i try to update progress bar from another thread then i get errors and maya application gets closed .

Error

QPixmap: It is not safe to use pixmaps outside the GUI thread

maya.bin: Fatal IO error: client killed

Segmentation fault (core dumped)

Can anyone  tell me why i am getting this error and how to solve this ?

[kollig]

To my knowledge and experience all GUI updates have to be done in the main Maya thread. Meaning it is not safe to use progressBar from another thread.

In C++ I am using MGlobal::executeCommandOnIdle to get the command executed from the main thread.

May be you can use evalDeferred?!

[Anonymous]

On click  submit button the command runs a function which updates progress bar but that function is too big and I can't do anything after click on submit button till the execution gets finished therefore I am running that function in the background using thread.
can you suggest me any other idea ?

[kollig]

On submit do all startup GUI stuff needed to be done. Then start the thread with your function. Whenever your function wants to update the progress bar, which should be a single (mel) command, use evalDeferred for this command.

This means that the progress bar is updated using Maya's main thread/event loop. At least I think that evalDeferred works like this, I haven't tested it. MGlobal::executeCommandOnIdle works like this.