Hi,

If it is indeed a bug, you should be able to reproduce it if you enable 
memory debugging by defining the various macros in pov_mem.cpp (in 
particular MEM_GUARD) when compiling POV-Ray.

The other, and more likely, option - if this only occurs during long 
renders - may very well be memory corruption due to overheating 
problems. Nowadays this also tends to be a problem for memory due to 
overall heat being generated.

Thorsten

On 06.04.2025 09:09, William F Pokorny wrote:
> Posting as a hook so others who might see this failure can find it and 
> provide information.
> 
> If you have seen this issues or have just hit it, please post here - 
> along with environment, running conditions, frequency, etc.
> 
> ---
> 
> In the last six months or so I've been using the animation facilities in 
> POV-Ray (yuqk) more than ever. Sometimes to create actual animations, 
> but more often as a way to explore feature options. Or, as with the 
> text{} object recently, to run down some crash already, infrequently, 
> seen in non-animation (single frame/image) renders.
> 
> Today, for the second time in the last month, I had a long running 
> animation core dump with a "malloc(): unsorted double linked list 
> corrupted" error(*). Both times the animation frames, rendering was 
> working in the background while I was doing other interactive work. Both 
> times the animation completed without issue once resumed.
> 
> I'm kicking off some intentionally long running (many frame) dummy 
> animations trying to trip this error while running my debug compile. I'm 
> hoping to capture an annotated core dump file. Maybe I'll get lucky, but 
> I doubt it. I guess something like valgrind an option - if I find myself 
> really motivated.
> 
> ---
> 
> Linux. x86-64. My yuqk, v3.8 based fork releases R19 and working state, 
> R20 code. Both times the scenes were small - with memory requirements 
> <100MB.
> 
> lsb_release -a :
>      No LSB modules are available.
>      Distributor ID: Ubuntu
>      Description:    Ubuntu 24.04.2 LTS
>      Release:        24.04
>      Codename:       noble
> g++ --version : g++ (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
> ldd --version : ldd (Ubuntu GLIBC 2.39-0ubuntu8.4) 2.39
> uname -r      : 6.8.0-57-generic
> 
> Bill P.
> 
> (*) - The error message comes from glibc prior to things crashing.

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