Jemalloc option in README.md

[alxarno]

Issue

I ran into a problem with constantly growing RSS usage, when processing thousands of images sequentially. I used the MALLOC_ARENA_MAX environment variable, which improved the situation, but after the end of the image processing phase (in my application), a large chunk of memory was left by the process ~1.5GB. I started to investigate why this was happening and came to the conclusion that MALLOC_ARENA_MAX does not completely eliminate memory fragmentation. So I decided to replace the standard allocator in libvips, with jemalloc, which is made for such use cases. As a result, this completely fixed the situation, and minimized RSS usage as much as possible (as if libvips had never been used).

Solution

I think it would be useful to add such a feature to the description so that people don't waste their time researching such problems.