vulkan - Concurrent use of VkSamplers?

Question

So a VkSampler is created with a VkSamplerCreateInfo that just has a bunch of configuration settings, that as far as I can see would just define a pure function of some input image.

They are described as:

VkSampler objects represent the state of an image sampler which is used by the implementation to read image data and apply filtering and other transformations for the shader.

One use (possibly only use) of VkSampler is to write them to descriptors (such as VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER) for use in descriptor sets that are bound to pipelines/shaders.

My question is: can you write the same VkSampler to multiple different descriptors? from the same or multiple different descriptor pools? even if one of the current descriptors is in use in some currently executing render pass?

Can you use the same VkSampler concurrently from multiple different render passes / subpasses / pipelines?

Put another way, are VkSamplers stateless? or do they represent some stateful memory on the device and so you shouldn't use the same one concurrently?

question from:https://stackoverflow.com/questions/65895414/concurrent-use-of-vksamplers

Answer 1

VkSampler objects definitely have data associated with them, so it would be wrong to call them "stateless". What they are is immutable. Like VkRenderPass, VkPipeline, and similar objects, once they are created, their contents cannot be changed.

Synchronization between accesses is (generally) needed only for cases when one of the accesses is a modification operation. Since VkSamplers are immutable, there are no modification operations. So synchronization is not needed for cases where you're accessing a VkSampler from different threads, commands, or whathaveyou.

The only exception is the obvious one: vkDestroySampler, which requires that submitted commands that use the sampler have completed before calling the function.