+++ This bug was initially created as a clone of Bug #1393709 +++

Description of problem:
=======================
On my systemic setup seeing lot of iobuff leaks in statedump even without much load on the client

I have setup a systemic testbed, where I have a 4x2 volume spanning 4 nodes.
I hav enabled below features, look at vol info:
Volume Name: drvol
Type: Distributed-Replicate
Volume ID: 2f0e5510-fe47-4ce8-906e-6ddc7f9334ca
Status: Started
Snapshot Count: 0
Number of Bricks: 4 x 2 = 8
Transport-type: tcp
Bricks:
Brick1: 10.70.35.191:/rhs/brick1/drvol
Brick2: 10.70.37.108:/rhs/brick1/drvol
Brick3: 10.70.35.3:/rhs/brick1/drvol
Brick4: 10.70.37.66:/rhs/brick1/drvol
Brick5: 10.70.35.191:/rhs/brick2/drvol
Brick6: 10.70.37.108:/rhs/brick2/drvol
Brick7: 10.70.35.3:/rhs/brick2/drvol
Brick8: 10.70.37.66:/rhs/brick2/drvol
Options Reconfigured:
cluster.use-compound-fops: on
diagnostics.count-fop-hits: on
diagnostics.latency-measurement: on
features.uss: enable
features.quota-deem-statfs: on
features.inode-quota: on
features.quota: on
features.barrier: disable
cluster.shd-max-threads: 16
performance.md-cache-timeout: 600
performance.cache-invalidation: true
features.cache-invalidation-timeout: 300
features.cache-invalidation: on
transport.address-family: inet
performance.readdir-ahead: on
nfs.disable: on


I then mounted the volume on 10 different clients and did following IOs:
From all clients:===> started taking statedump of the fuse mount process every 5 minutes and moving them to a dedicated directory for each host on the mount point(so into gluster vol)
From all clients:====>collecting top and cpu usage every 2 mins and appending the contents into a file for each host on the mount point(so into gluster vol)

I see that even 16 GB clients have consumed almost complete memory
byjust doing the above two actions in just 1.5 days

Version-Release number of selected component (if applicable):
[root@rhs-client23 gluster]# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 7.2 (Maipo)
[root@rhs-client23 gluster]# rpm -qa|grep gluster
glusterfs-libs-3.8.4-3.el7rhgs.x86_64
glusterfs-client-xlators-3.8.4-3.el7rhgs.x86_64
glusterfs-api-3.8.4-3.el7rhgs.x86_64
glusterfs-debuginfo-3.8.4-3.el7rhgs.x86_64
glusterfs-3.8.4-3.el7rhgs.x86_64
glusterfs-fuse-3.8.4-3.el7rhgs.x86_64
glusterfs-cli-3.8.4-3.el7rhgs.x86_64
[root@rhs-client23 gluster]# 


Statedumps attached

--- Additional comment from nchilaka on 2016-11-10 05:22:17 EST ---

From further tests, it seems with all likeliness that it is due to appends

I just appended a file in the mount with TOP and FREE -h command output every 2 minutes.
With every loop the mem consumption seemed to increase by 5MB

I have taken statedumps in below intervals
[root@rhs-client45 gluster]# date;free -h;date ;kill -USR1 16078;date
Thu Nov 10 15:39:39 IST 2016
              total        used        free      shared  buff/cache   available
Mem:            15G        504M         11G         24M        3.2G         14G
Swap:          7.9G         51M        7.8G
Thu Nov 10 15:39:39 IST 2016
Thu Nov 10 15:39:39 IST 2016
[root@rhs-client45 gluster]# ls
glusterdump.16078.dump.1478772579
[root@rhs-client45 gluster]# date;free -h;date ;kill -USR1 16078;date
Thu Nov 10 15:41:05 IST 2016
              total        used        free      shared  buff/cache   available
Mem:            15G        509M         11G         24M        3.2G         14G
Swap:          7.9G         51M        7.8G
Thu Nov 10 15:41:05 IST 2016
Thu Nov 10 15:41:05 IST 2016
[root@rhs-client45 gluster]# ll
total 596
-rw-------. 1 root root 301703 Nov 10 15:39 glusterdump.16078.dump.1478772579
-rw-------. 1 root root 305566 Nov 10 15:41 glusterdump.16078.dump.1478772665
[root@rhs-client45 gluster]# ll
total 596
-rw-------. 1 root root 301703 Nov 10 15:39 glusterdump.16078.dump.1478772579
-rw-------. 1 root root 305566 Nov 10 15:41 glusterdump.16078.dump.1478772665
[root@rhs-client45 gluster]# 
[root@rhs-client45 gluster]# ll
total 596
-rw-------. 1 root root 301703 Nov 10 15:39 glusterdump.16078.dump.1478772579
-rw-------. 1 root root 305566 Nov 10 15:41 glusterdump.16078.dump.1478772665
[root@rhs-client45 gluster]# date;free -h;date ;kill -USR1 16078;date
Thu Nov 10 15:44:20 IST 2016
              total        used        free      shared  buff/cache   available
Mem:            15G        518M         11G         24M        3.2G         14G
Swap:          7.9G         51M        7.8G
Thu Nov 10 15:44:20 IST 2016
Thu Nov 10 15:44:20 IST 2016
[root@rhs-client45 gluster]# 


Attached are new statedumps

--- Additional comment from nchilaka on 2016-11-10 05:23 EST ---



--- Additional comment from nchilaka on 2016-11-10 05:33:56 EST ---

Just a Note: Compound FOPs is enabled :)

--- Additional comment from Krutika Dhananjay on 2016-11-11 05:14:31 EST ---

So there is indeed iobuf leak as per the statedump attached.

Just to confirm that it is compound fops indeed that is contributing to the leak (and not any of the several other options enabled on the volume), I did a dd on a plain replicate volume without compound-fops, captured statedump before and after the dd - there was no increase in active iobufs. Once I enabled compound fops and did a dd again, the number of active iobufs had increased from 1 to 6 and after another dd from 6 to 13.
Also checked afr changes for compound fops - I didn't find any mem leaks there. So the only possibility is leaks at the protocol/client layer which I am investigating through code reading at the moment.

--- Additional comment from Krutika Dhananjay on 2016-11-16 07:54:40 EST ---

Found the leaks. Nice catch, Nag! :)