Ask about Heap


(Nguyễn Hữu Khôi) #1

I read ES document and it recommend that we should set under 50% of memory. However, what happen if ES use more than this amount? And how can we know if ES need more memory? Thank you!


#2

In general you should expect search performance degradation or if give ES to much heap OS may kill ES process (OOM killer).
IMHO the main reason to keep RAM 50/50 is the OS file cache, where hot file blocks accessed by search keeps and can be reused from RAM. If you give ES more memory you'll get much more read I/O from disks. Another pitfall is that you can move system into swap and that kills indexing and search performance.


(system) #3

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