[vulkan] Synchronization issue: vkAcquireNextImage uses a semaphore which is in use. about bgfx HOT 4 CLOSED

I can confirm the error from Vulkan goes away when explicitly kick(true) instead of kick(false) which causes to immediately synchronize on the submitted command buffer.

from bgfx.

cc @pezcode

from bgfx.

I managed to make some changes that seems to fix the issue, without breaking anything. Needs more testing. Will open PR if I think it's ready for review.

from bgfx.

As you can see, the fence is not waited for before acquiring frame N + 2

The issue is that (as you mentioned) the image order is not guaranteed. So you can not know the next image, and hence can not know the associated fence before calling vkAcquireNextImageKHR(). Not sure what the correct fix is here, but I feel like the missing synchronization should happen at another point.

Calling kick(true) works because it is essentially vkQueueWaitIdle(), but destroys any kind of performance gains by having multiple frames in flight.

from bgfx.