Item queue present only for a host behind a proxy

[andrea.g.els]

I've got a strange issue with a single host behind a proxy

server:

Zabbix 3.4.8 + mariadb

2 cpu , 4 gb of ram

12 hosts , 1 proxy , 5 esxi servers no snmp/ipmi ,about 115 vps

Checking the queue I can see about 50 items , all belongs to a single host behind the proxy.

All the others agents behind the same proxy (3) does not show the problem, and all are in the same subnet of the proxy.

All the items on this one are standard templates except for three mysql query (application specific) which take up to 4 seconds , and are polled every 15 minutes.

I've searched a bit , and almost always it's a db problem , but the fact that the queue belongs only to a single host puzzles me .

Any idea about how to tackle this problem?

It's the proxy or client that need to be tuned ?

[andrea.g.els]

Update :
pruned thousands of items:
from

to:


The vps value almost dropped to half , but the queue still persists .
The queue appeared when we inserted the new host :

[LenR]

Queue for a single host is probably not a DB issue, it is a slow or not responding host. Are the items all one type, Agent or Agent (active)? Try zabbix_get for a few of those items from your zabbix_proxy. It could be firewall, wrong "allowed" IP in the agent config or a network firewall between the proxy and host.

[andrea.g.els]

all the items are Agent .
tried with zabbix-get (from proxy) and all the items are responding , so firewall is OK.

The slowest one is a sql query which takes about 4 seconds (timeout is 15 seconds)

UserParameter=myapp.count,HOME=/var/lib/zabbix mysql -N my_db_name < /opt/zabbix_scripts/count_items.sql

[andrea.g.els]

Somehow managed to solve the issue , but no root cause found .
steps:

• restarted zabbix-agent service on both the proxy and the slow responding client
• restarted zabbix-proxy service on the proxy
• disabled the four custom items on the client then re-enabled them one-by-one

the ites were queued for about 45/60 minutes (so queue = 1) , then queue gone to 0