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by jacobsenscott
1000 days ago
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I'm correct in practice. There are scenarios where ruby might free memory, but ruby is mostly used for rails, and you won't ever see that under a standard rails workload. It will plataue and stay there until a restart. When people see this they think it's a "bug" or a "leak" but it isn't. On the last fairly large rails app I tried to use jemalloc on there was no change in memory usage. I believe that advice is a bit outdated. Also note using jemalloc doesn't cause memory to be freed to the system. It reduces fragmentation, at the cost of cpu cycles. There's no free lunch. |
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Yes, because extra empty pages are released at the end of major GC, which is occasional, and most web application will cyclicaly use enough memory that they will stabilize / plateau at one point.
> I believe that advice is a bit outdated.
It absolutely isn't, your anecdote doesn't mean much compared to the countless reports you can find out there.
> Also note using jemalloc doesn't cause memory to be freed to the system.
Yes it does, it has a decay mecanism, most allocators do. https://jemalloc.net/jemalloc.3.html
> It reduces fragmentation
Yes, and that allows it to have more free pages that it can release.
> at the cost of cpu cycles
Compared to glibc, not so much.