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!


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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