POV-Ray : Newsgroups : povray.binaries.images : Likely subsurface thread safety issue. Known? Server Time: 20 Jun 2019 20:11:25 GMT
  Likely subsurface thread safety issue. Known? (Message 1 to 3 of 3)  
From: William F Pokorny
Subject: Likely subsurface thread safety issue. Known?
Date: 26 Feb 2018 14:15:35
Message: <5a941687$1@news.povray.org>
See the attached image. Three columns left to right with images in the 
first two rows rendered with 1, 2 and 4 threads. The bottom row is an 8x 
multiple of the image pixel differences.

Using the subsurface.pov scene shipped with POV-Ray and the command:

povray -j -d -c -p +wt4 subsurface.pov

changing only the number of threads each time. Ubuntu 16.04. Master 
branch as of commit 9c67174 Sat Jan 6 11:58:42 2018 +0100 "Merge branch 
'release/v3.8.0'"

I've not seen any differences between single thread renders in a half 
dozen runs. Always some difference in multi-thread runs, but the 
signature is interesting in that POV-Ray seems to match on some of the 
sub blocks. More often ones at the top match, but I've seen render-image 
pairs with matching blocks better than half way down into the image.

I know the SSLT code is not in it's final form. Is this a known issue or 
should we open up a github issue for it?

Bill P.


Post a reply to this message


Attachments:
Download 'sslt_thread_safety.jpg' (235 KB)

Preview of image 'sslt_thread_safety.jpg'
sslt_thread_safety.jpg


 

From: clipka
Subject: Re: Likely subsurface thread safety issue. Known?
Date: 26 Feb 2018 15:49:27
Message: <5a942c87@news.povray.org>
Am 26.02.2018 um 15:15 schrieb William F Pokorny:

> I know the SSLT code is not in it's final form. Is this a known issue or
> should we open up a github issue for it?

I'd say, open an issue so that it isn't forgotten next time SSLT is
modified.


Post a reply to this message

From: William F Pokorny
Subject: Re: Likely subsurface thread safety issue. Known?
Date: 27 Feb 2018 11:45:10
Message: <5a9544c6$1@news.povray.org>
On 02/26/2018 10:49 AM, clipka wrote:
> Am 26.02.2018 um 15:15 schrieb William F Pokorny:
> 
>> I know the SSLT code is not in it's final form. Is this a known issue or
>> should we open up a github issue for it?
> 
> I'd say, open an issue so that it isn't forgotten next time SSLT is
> modified.
> 

See:

https://github.com/POV-Ray/povray/issues/350

Bill P.


Post a reply to this message

Copyright 2003-2008 Persistence of Vision Raytracer Pty. Ltd.