GPU not being release after closing material editor

In cycles, after closing the material editor, the GPU seems still remains to be
used. (attached image is GPU usage after closing material window)

  1. Open materials
  2. Import material from library.
  3. Close material editor window.
    ->GPU still being used.
    (this seems to happen if the auto-update is ON for the material)

Expected result:

  1. to release GPU and material auto-update should pause.
  2. When re-opening material editor, have the up-to-that-point render shown
    in thumbnail and continue to update the material
  3. Once the render update is done, should cache and no need to update again for that file
    (if material saved then the thumbnail should be kept to used for other files,
    i.e., auto update should no longer needed after import [perhaps unless user wishes to run update of material], also a manual pause of material update is good to have. )

@Toshiaki_Takano, there is still one thumbnail visible in your screenshot: the environment.

The next public WIP will have a new advanced option PreviewSamples that you can tweak. I added this yesterday.

@andy, do you know if the preview job system just continues if thumbnails are no longer visible?

That’s great news! Thank you.

I tried again with different side bar panel, but seems to still do the render preview after closing.

Other thing was though the GPU processing stopped(so I’m guessing the preview is finished) When I reopen the material window the preview pane is blank.(below top screenshot)
When I select another material then go back to the material previously highlighted, the preview rendering starts from scratch again…
I tried turning off the Auto-update of the preview (second screenshot below)
I get the triangle for the update notice, but preview is blank.

wondering if anyone else is seeing the same?
running on GTX1050

The larger preview is different from the small thumbnail. Clicking it open even after the thumbnail has been done will currently start a render of it at the requested size. Resizing the preview will also cause a rerender. The initial preview is white precisely because it hasn’t rendered yet. Once rendered it should be cached for that size, though.

Got it. Thank you for the clarification.