Hello,
I recently updated my CPU and got a Ryzen 9 3900X with 12 cores and 24 threads and that caused me to find what I think is a bug. To be clear, the program works fine, the image is rendered, so it's more of a nuisance than a real problem.
What happens, is that for images wider than 1931 pixels, certain thread counts will cause 50% of the image centered horizontally to be renderd first, before any of the other parts are touched. I tested this for multiple numbers of threads but my post, including a screenshot never made it through, so I'm trying my best reproducing it from memory here without a screenshot.
The behavior doesn't consistently appear for all thread counts beyond a threshold:
Working normally: up to 19, 21, 22, 25, 27, ... 32
Bugged: 20, 23, 24, 26, 28
Not tested: 29, 30, 31, 33 and higher. Beyond about 26 threads my system starts hanging badly so testing it for a few seconds takes up to several minutes because everything freezes, so I stopped there. Right now I'm using 16 threads for exploring as a workaround, it's not ideal but I'd rather see all of the image in low-res sooner than having only part of it visible for several minutes once I zoom a bit deeper.
The bug seems to appear to a lesser extent between 1921 and 1930, such that instead of 25% left and 25% right only a very narrow portion of the image is rendered later (roughly whatever is the difference to 1920, so about 10 pixels).
Best regards,
Phillip
//edit: Image added below 
Hello,
I recently updated my CPU and got a Ryzen 9 3900X with 12 cores and 24 threads and that caused me to find what I think is a bug. To be clear, the program works fine, the image is rendered, so it's more of a nuisance than a real problem.
What happens, is that for images wider than 1931 pixels, certain thread counts will cause 50% of the image centered horizontally to be renderd first, before any of the other parts are touched. I tested this for multiple numbers of threads but my post, including a screenshot never made it through, so I'm trying my best reproducing it from memory here without a screenshot.
The behavior doesn't consistently appear for all thread counts beyond a threshold:
Working normally: up to 19, 21, 22, 25, 27, ... 32
Bugged: 20, 23, 24, 26, 28
Not tested: 29, 30, 31, 33 and higher. Beyond about 26 threads my system starts hanging badly so testing it for a few seconds takes up to several minutes because everything freezes, so I stopped there. Right now I'm using 16 threads for exploring as a workaround, it's not ideal but I'd rather see all of the image in low-res sooner than having only part of it visible for several minutes once I zoom a bit deeper.
The bug seems to appear to a lesser extent between 1921 and 1930, such that instead of 25% left and 25% right only a very narrow portion of the image is rendered later (roughly whatever is the difference to 1920, so about 10 pixels).
Best regards,
Phillip
//edit: Image added below :)
edited Sep 19 '19 at 7:17 am
