[System Test] Found memory_used_storage stat to be having negative value ('memory_used_storage': -56401)

Build: 6.5.0-4959
Test: -test tests/integration/test_allFeatures_madhatter_durability.yml -scope tests/integration/scope_Xattrs_Madhatter.yml
Scale: 3
Day: 4

Found memory_used_storage having negative value in 2 of the index nodes:

172.23.96.95 : index
stats : [(u'memory_used_storage', -88213)]

172.23.99.21 : index
stats : [(u'memory_used_storage', -56401)]

Cluster config ##################
index : 6 ===== > [172.23.104.155:8091 172.23.104.70:8091 172.23.96.253:8091 172.23.96.95:8091 172.23.99.20:8091 172.23.99.21:8091] ###########
fts : 2 ===== > [172.23.104.156:8091 172.23.104.157:8091] ###########
kv : 12 ===== > [172.23.104.164:8091 172.23.104.61:8091 172.23.104.67:8091 172.23.104.88:8091 172.23.106.188:8091 172.23.108.103:8091 172.23.97.119:8091 172.23.97.121:8091 172.23.97.122:8091 172.23.97.242:8091 172.23.99.11:8091 172.23.99.25:8091] ###########
cbas : 3 ===== > [172.23.104.5:8091 172.23.105.107:8091 172.23.97.239:8091] ###########
eventing : 3 ===== > [172.23.104.87:8091 172.23.96.148:8091 172.23.98.135:8091] ###########
n1ql : 2 ===== > [172.23.96.251:8091 172.23.96.252:8091] ###########

cbcollect logs:

url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.104.155.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.104.156.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.104.157.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.104.164.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.104.5.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.104.61.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.104.67.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.104.70.zip
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url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.105.107.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.106.188.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.108.103.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.96.148.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.96.251.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.96.252.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.96.253.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.96.95.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.97.119.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.97.121.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.97.122.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.97.239.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.97.242.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.98.135.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.99.11.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.99.20.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.99.21.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1577376708/collectinfo-2019-12-26T161150-ns_1%40172.23.99.25.zip