If you encounter this message and experience slow performance, use the following strategies to free up VRAM:
The lead systems engineer’s voice crackled, tight with panic. “The manifold is collapsing. Every thread you spawn, it tries to resolve the entire timeline. We had to cap samples per thread at thirty-two thousand. Anything higher, and the cores start bleeding heat into the real world.”
For Blender Cycles (as of 4.0+), this parameter is not user-accessible in the UI. However, you can set it via Python script: If you encounter this message and experience slow
“Override the cap,” he said.
: In some versions, this is considered a "developer-only" debug message that essentially means the engine "would have liked a bit more memory" but can still function. Common Causes We had to cap samples per thread at thirty-two thousand
When you increase num_samples_per_thread , you are effectively asking the renderer to allocate a larger per thread. The total memory required is roughly:
The warning message indicates that the rendering engine has automatically reduced the number of samples per thread to 32768. This reduction is a safeguard to prevent potential performance issues or crashes. The "num samples per thread" refers to the number of samples taken by each thread during the rendering process. Samples are essentially data points used to generate the final image. When the number of samples per thread exceeds 32768, the rendering engine may encounter difficulties in processing the data efficiently, leading to performance degradation or instability. : In some versions, this is considered a
In short: The renderer hit a hardware or software limit and had to scale back its workload per thread, which can hurt efficiency.