Advice on Heap usage

[royal_man]

Node: 12cpu + 45GB RAM
I have 1 shard on 1 node.
size of 1 shard: 12GB
Heap assigned: 20GB
Based on the graph below. I think I should reduce the heap size but it is recommended to keep heap 50% of the RAM. Can someone suggest.

Also, elasticsearch_transport_rx_packets_total keeps on increasing and search speed becomes bad even if the CPU is 60% utilized. What changes should I perform ?

[DavidTurner]

@royal_man

it is recommended to keep heap 50% of the RAM

This is not the case. The docs say (emphasis mine):

Set Xmx and Xms to no more than 50% of your physical RAM.

You can set it to less, for sure, and this can sometimes improve performance.

[royal_man]

@royal_man

Also, elasticsearch_transport_rx_packets_total keeps on increasing and search speed becomes bad even if the CPU is 60% utilized. What changes should I perform ?

@DavidTurner Could you also explain this

Also, elasticsearch_transport_rx_packets_total keeps on increasing and search speed becomes bad even if the CPU is 60% utilized. What could be the cause for this. ?

[royal_man]

I found this discussion. Thanks.

JVM Heap Advice from documentation

Note that the documentation gives 50% as a recommended upper limit, not a target: Set Xmx to no more than 50% of your physical RAM You can of course set it lower. I think that reducing the heap size also reduces the space available for off-heap data (they share a limit) but you are right that it increases the space available for filesystem cache. Would that improve performance? It depends™ It means a full GC would be faster, but maybe more frequent, and means it can cache …

[DavidTurner]

I've no idea what elasticsearch_transport_rx_packets_total is, nor how it relates to your original question. Maybe open a new thread in case someone else knows.