[Gluster-devel] Huge VSZ (VIRT) usage by glustershd on dummy node

[Oleksandr Natalenko]

Hello.

We use v3.7.11, replica 2 setup between 2 nodes + 1 dummy node for 
keeping volumes metadata.

Now we observe huge VSZ (VIRT) usage by glustershd on dummy node:

===
root     15109  0.0 13.7 76552820 535272 ?     Ssl  тра26   2:11 
/usr/sbin/glusterfs -s localhost --volfile-id gluster/glustershd -p 
/var/lib/glusterd/glustershd/run/glustershd.pid -l 
/var/log/glusterfs/glustershd.log -S 
/var/run/gluster/7848e17764dd4ba80f4623aecb91b07a.socket --xlator-option 
*replicate*.node-uuid=80bc95e1-2027-4a96-bb66-d9c8ade624d7
===

that is ~73G. RSS seems to be OK (~522M). Here is the statedump of 
glustershd process: [1]

Also, here is sum of sizes, presented in statedump:

===
# cat /var/run/gluster/glusterdump.15109.dump.1465200139 | awk -F '=' 
'BEGIN {sum=0} /^size=/ {sum+=$2} END {print sum}'
353276406
===

That is ~337 MiB.

Also, here are VIRT values from 2 replica nodes:

===
root     24659  0.0  0.3 5645836 451796 ?      Ssl  тра24   3:28 
/usr/sbin/glusterfs -s localhost --volfile-id gluster/glustershd -p 
/var/lib/glusterd/glustershd/run/glustershd.pid -l 
/var/log/glusterfs/glustershd.log -S 
/var/run/gluster/44ec3f29003eccedf894865107d5db90.socket --xlator-option 
*replicate*.node-uuid=a19afcc2-e26c-43ce-bca6-d27dc1713e87
root     18312  0.0  0.3 6137500 477472 ?      Ssl  тра19   6:37 
/usr/sbin/glusterfs -s localhost --volfile-id gluster/glustershd -p 
/var/lib/glusterd/glustershd/run/glustershd.pid -l 
/var/log/glusterfs/glustershd.log -S 
/var/run/gluster/1670a3abbd1eea968126eb6f5be20322.socket --xlator-option 
*replicate*.node-uuid=52dca21b-c81c-48b5-9de2-1ed37987fbc2
===

Those are 5 to 6G, which is much less than dummy node has, but still 
look too big for us.

Should we care about huge VIRT value on dummy node? Also, how one would 
debug that?

Regards,
   Oleksandr.

[1] https://gist.github.com/d2cfa25251136512580220fcdb8a6ce6