jira get numActive connection pool

[Ivan Nepryakhin]

Environmnet:
Jira v7.13.12 ( Ubuntu 18.04.4 LTS )
Oracle Database

Hi community!

I have a task about:
"Monitoring numActive connections  with BD"

1. I view this  items from "the Database Monitoring page"
And i see:

2. from OS:

jirahost$ ss -tp | grep <DB IPaddress> | grep <DB TPCport> | wc -l
jirahosr$ 35

My questions:
1. How i can get  numActive connections for my monitoring system (zabix)
 (I know about JMX, but i not sure what its will definitely decide my task)

2. Why count of connections from OS -> DB almost always 35(sometime 32-34) , while 
numActive min = 9; max=14 for the same period time.
In general: Why connections - 35 and from which settings it is sum?

I will Very appreciate for any help!!

/// sorry for my english