I've been playing around with wimlib lately (on Windows 11 x64 if that matters), and depending on whatever else I have running in the background at the time, when using solid LZMS compression, my PC may not always have enough RAM available to use all the threads that the CPU could otherwise get to working on the task compression task.
When that happens, wimlib outputs the following message:
While falling back to single-threaded lowers memory usage quite significantly and almost always ensures success, I've been thinking, the program probably could just lower the number of threads by 1 and try again, either until that lowered the required amount of memory enough for it to be able to allocate said amount, or until the number of threads gets down to 1.[WARNING] Couldn't create parallel chunk compressor: Ran out of memory.
Falling back to single-threaded compression.