alt Hacker NewsMemory allocation behaviour has visible impact also for users of managed languages, and the behaviour of software for end users.
In our Python program, a bit of numpy processing of large pictures led to 100 GB not being returned to the OS by glibc's default allocator and the machine running out of memory shortly after. With jemalloc's reliable memory return settings, those problems disappear.
I'm in the same boat, I just switched to using it for Kavita, which only does some basic open Image -> Thumbnail to smaller size -> write to disk when importing new comics/books and on linux, memory could swell to 10GB and never get released. Switched to jemalloc and instantly memory stayed well below 1GB.