What is memory RSS in server status?

Support
1

Hi,
Here is my server status --
Backup Storage Directory : .backup
CPU Load : 2.41 %
Connection Timeout : 1h
Export Storage Directory : .exports
Memory Heap : 3.6G (Max: 12G)
Memory Mode : DEFAULT
Memory Query Blocks : 0B (Max: 4.6G)
Memory RSS : 15G
Platform Arch : amd64
Platform OS : Linux 3.10.0-693.5.2.el7.x86_64, Java 1.8.0_151
Query All Graphs : false
Query Timeout : 1h
Security Disabled : false
Stardog Home : /scratch/shishir18106/stardog_home
Stardog Version : 7.0.2
Strict Parsing : true
Uptime : 32 minutes 48 seconds

What is memory RSS in server status?
my jvm settings are : export STARDOG_SERVER_JAVA_ARGS="-Xmx12g -Xms12g -XX:MaxDirectMemorySize=16g"

I have observed that memory RSS values go beyond what I have assigned in JVM settings?

Please explain to me ?

--Thank You

2

Resident Set Size? That's just a guess.

3

I want to know why it is increasing beyond assigned limit?
I am asking because, sometimes I am facing memory errors while querying.

4

RSS would include memory that has spilled to disk so it can go beyond what has been physically allocated. Again just a guess :slight_smile:

5

ok.
It would go in which portion of disk.
I mean where the stardog server is installed or disk space where stardog_home resides.
Actually in my case, stardog install disk and stardog_home are at different disk.

6

I don't know exactly but I'm fairly confident it doesn't go in the install disk. I think it would be either STARDOG_HOME or TMP or whatever you've setup temp to be if you didn't go with the system default.

7

I have checked, memory rss is occupied in RAM not in disk.
But why it is going beyond specified memory?

as you ca see.

[shishir18106@compute-0-2 ~]$ free -g
total used free shared buff/cache available
Mem: 94 46 11 0 35 46
Swap: 29 25 4
this is free memory in my system.

Backup Storage Directory : .backup
CPU Load : 0.00 %
Connection Timeout : 1h
Export Storage Directory : .exports
Memory Heap : 3.3G (Max: 12G)
Memory Mode : DEFAULT
Memory Query Blocks : 0B (Max: 4.6G)
Memory RSS : 19G
Platform Arch : amd64
Platform OS : Linux 3.10.0-693.5.2.el7.x86_64, Java 1.8.0_151
Query All Graphs : false
Query Timeout : 1h
Security Disabled : false
Stardog Home : /scratch/shishir18106/stardog_home
Stardog Version : 7.0.2
Strict Parsing : true
Uptime : 11 hours 47 minutes 12 seconds

this is stardog server status.
Memory RSS: 19G

Now observe change in free memory after when stop server .

[shishir18106@compute-0-2 ~]$ free -g
total used free shared buff/cache available
Mem: 94 27 30 0 36 65
Swap: 29 25 4

now it is 30G(11G + 19G).
It is going beyond I have assigned.
What can be the reason behind this?

8

RSS is all the memory used by the Stardog server process, it includes both Java heap and offheap memory. If you allowed 12G for heap and 16G for direct memory, then 19G RSS is within limits.

Under certain workloads Stardog can go a bit beyond limits (for example under writes) or when certain background processes run (e.g. data compaction).

Memory issues during querying are most likely related to having no statistics and thus suboptimal query plans.

Best,
Pavel

9

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.