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I very recently used jemalloc to resolve a memory fragmentation issue that caused a service to OOM every few days. While jemalloc as it is will continue to work, same as it does today, I wonder what allocator I should reach for in the future. Does anyone have any experiences to share regarding tcmalloc or other allocators that aim to perform better than stock glibc?
I’ve wondered about this before but never when around people who might know. From my outsider view, jemalloc looked like a strict improvement over glibc’s malloc, according to all the benchmarks I’d seen when the subject came up. So, why isn’t it the default allocator?
Good times.
Earlier quoted context omitted.
Why would they have to change? Sometimes software development is largely "done" and there isn't much more you need to do to a library.
Memory allocators are something I expect to rapidly degrade in the absence of continuous updates as the world changes underneath you. Changing page sizes, new ucode latencies, new security features etc. all introduce either outright breakage or at least changing the optimum allocation strategy and making your old profiling obsolete. Not to mention the article already pointed out one instance where a software stack (K…
I’ve wondered about this before but never when around people who might know. From my outsider view, jemalloc looked like a strict improvement over glibc’s malloc, according to all the benchmarks I’d seen when the subject came up. So, why isn’t it the default allocator?
Kind of nuts that he worked on Jemalloc for over a decade while having personal preference for garbage collection. I'm surprised he doesn't have more regret.
I believe there’s no other allocator besides jemalloc that can seamlessly override macOS malloc/free like people do with LD_PRELOAD on Linux (at least as of ~2020). jemalloc has a very nice zone-based way of making itself the default, and manages to accommodate Apple’s odd requirements for an allocator that have tripped other third-party allocators up when trying to override malloc/free.
I’ve wondered about this before but never when around people who might know. From my outsider view, jemalloc looked like a strict improvement over glibc’s malloc, according to all the benchmarks I’d seen when the subject came up. So, why isn’t it the default allocator?
A while back, I had a conversation with an engineer who maintained an OS allocator, and their claim was that custom allocators tend to make one process's memory allocation faster at the expense of the rest of the system. System allocators are less able to make allocation fair holistically, because one process isn't following the same patterns as the rest.
Which is why you see it recommended so frequently with services, where there is generally one process that you want to get preferential treatment over everything else.