CODEWITHSUNDEEP
vulkan
Siliace
Siliace

Reputation: 652

Wait for a VkFence in a thread before it has been submitted by another thread

I'm implementing asynchronous VkCommandBuffer recording to improve geometry and texture loading in my rendering engine.

I'm facing validation issue about VkFence being in use in two different threads:

UNASSIGNED-Threading-MultipleThreads(ERROR / SPEC): msgNum: 337425955 - Validation Error: [ UNASSIGNED-Threading-MultipleThreads ] Object 0: handle = 0x90a67000000088d3, type = VK_OBJECT_TYPE_FENCE; | MessageID = 0x141cb623 | THREADING ERROR : vkQueueSubmit(): object of type VkFence is simultaneously used in thread 0x3344 and thread 0x2d3c

I've written a minimal example to reproduce my issue here: https://gist.github.com/siliace/fc2633ee2406d3cbc53a60857bb14776

When on line 18, gSubmitBeforeWaitFence is false, the worker thread will not wait until the main thread submitted the fence to wait for it, causing my validations errors. When gSubmitBeforeWaitFence is true, everything is fine.

Is it a bug of the validation layer and I should not have to wait for a VkFence to be submitted before waiting for it? Or is it a mistake from me? I would expect vkWaitForFences to be read-only operation so I don't see the point of forbiding this use.

And if my usage is wrong, is it written somewhere in the spec? I could not find it neighter in the documentation of vkQueueSubmut nor vkWaitForFences.

Thanks for your help !

Upvotes: 0

Views: 567

Answers (1)

krOoze
krOoze

Reputation: 13276

It is not allowed to use a fence while it is being vkQueueSubmited:

Host Synchronization

  • Host access to queue must be externally synchronized
  • Host access to fence must be externally synchronized

Upvotes: 2

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