VCO unable to display graphs like Links, Applications, QOE under Monitor Edge screen
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VCO unable to display graphs like Links, Applications, QOE under Monitor Edge screen

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Article ID: 367166

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Updated On:

Products

VMware VeloCloud SD-WAN

Issue/Introduction

All the graphs under Monitor Edge screen were unable to display the data. Graphs like Links, Applications, QOE and other graphs were impacted.

Environment

VMware SDWAN Orchestrator

Cause

There was very high CPU usage around 100% and due to this, the stats were not getting processed and hence they were getting queued up. Since all the stats data are stored in clickhouse database, so the graphs under Monitor Edge screen were impacted.

There were over 100k files in /var/lib/velocloud/file_store
 
mysql> select type,state,count(*) from VELOCLOUD_FILE_PROCESSING_QUEUE group by type, state;
+-----------------------+----------+----------+
| type                  | state    | count(*) |
+-----------------------+----------+----------+
| FLOWSTATS             | ENQUEUED |   109252 |
| GATEWAYINTERFACESTATS | ENQUEUED |        6 |
| HEALTHSTATS           | ENQUEUED |       80 |
| LINKQOE               | ENQUEUED |      164 |
| LINKSTATS             | ENQUEUED |       71 |
| PATHSTATS             | ENQUEUED |        2 |
| ROUTING_EVENTS        | ENQUEUED |        5 |
| CLICKHOUSE_INSERTS    | STARTED  |       24 |
| FLOWSTATS             | STARTED  |      886 |
| GATEWAYINTERFACESTATS | STARTED  |       19 |
| HEALTHSTATS           | STARTED  |     1975 |
| LINKQOE               | STARTED  |     1536 |
| LINKSTATS             | STARTED  |     2381 |
| PATHSTATS             | STARTED  |      444 |
| ROUTING_EVENTS        | STARTED  |       21 |
+-----------------------+----------+----------+
15 rows in set (0.44 sec)


mysql> select count(*),type from VELOCLOUD_FILE_PROCESSING_QUEUE;
+----------+--------------------+
| count(*) | type               |
+----------+--------------------+
|   116890 | CLICKHOUSE_INSERTS |
+----------+--------------------+
1 row in set (0.04 sec)


mysql>


root@lkt-vlo-vco1:/var/lib/velocloud/file_store# ls -l | wc -l
117162
root@lkt-vlo-vco1:/var/lib/velocloud/file_store#

 

The clickhouse process was stuck since clickhouse simultaneous query limit was reached.

2024.04.26 02:54:31.036033 [ 27705 ] {*************} <Error> DynamicQueryHandler: Code: 202. DB::Exception: Too many simultaneous queries. Maximum: 100. (TOO_MANY_SIMULTANEOUS_QUERIES), Stack trace (when copying this message, always include the lines below):2024.04.26 02:54:31.049187 [ 27703 ] {***********} <Error> DynamicQueryHandler: Code: 202. DB::Exception: Too many simultaneous queries. Maximum: 100. (TOO_MANY_SIMULTANEOUS_QUERIES)

Resolution

Below is the workaround to manually change the amount of connections allowed, we need to log in as root and modify a line from the file: /etc/clickhouse-server/config.xml 


Change:    <max_concurrent_queries>100</max_concurrent_queries>
To:            <max_concurrent_queries>300</max_concurrent_queries>


After making that change we can restart the click-house service like this:

 

root@vco:~# systemctl restart clickhouse-server.service


To view the status of the service:

 

root@vco:~# systemctl restart clickhouse-server.service

 

Above changes need to done in VCO CLI using a root user