alt Hacker NewsIn the Before Times, the vast majority of software was written in garbage collected language where a working knowledge of the relative merits of C memory allocators is not useful or particularly relevant.
Why would the scads of people writing JavaScript, Java, python, go, rails, etc need to be aware of jemalloc?
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>...the vast majority of software was written in garbage collected language
and even then recently it costed (us) quite a few months to blame JVM and later the default glibc memory allocator for running out native (not java heap memory) - had to exclude all possible native libs (zlib, zstd via jna), direct buffers, sockets, thread stacks and so on. Changing the malloc to jemalloc solved the issue, even though initially it was done for its debugging capabilities.
It's just a great memory allocator.
TL;DR: Because the runtime of most GC:d languages uses malloc for its internal data structures.
I work for the runtime team of JPG @ Oracle. We use malloc in Hotspot, quite a lot actually! Providing your JVM with a good malloc can improve the performance of the runtime, both in terms of CPU and memory, by quite a bit.
I don't think you need the details, but it's good to be aware that some mallocs are better than others, and there are multiple of them. Being aware of jemalloc is a good way of being aware of the facts I just mentioned :-).
Memory 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.