'Golang - many in use connections
#golang #oracle
Im trying to understand how the Max connection works. Basically I have this db configuration:
params.MinSessions = 5
params.MaxSessions = 6
params.SessionTimeout = 0
params.WaitTimeout = 5 * time.Second
params.SessionIncrement = 0
params.ConnClass = "GOLANGPOOL"
// Connect!
result, err := sql.Open("godror", params.StringWithPassword())
result.SetMaxIdleConns(0)
However I can see 242 connections using sql.DB.Stats:
DB Established Open Conn (use + idle): 242
DB Idle Conn: 0
DB In Use Conn: 242
DB Max Idle Closed: 766
DB Max Idle Time Closed: 0
DB Max Lifetime Closed: 0
DB Max Open Conn: 0
DB Wait Count: 0
DB Wait Duration (sec): 0
How is it possible? The limit shouldn't be 6?
Thanks
Solution 1:[1]
In Oracle connections and sessions are different concepts.
A connection is a network connection to the DB, while a session is an encapsulation of a user's interaction with the DB...
refering to this book, and Relation between Oracle session and connection pool.
Solution 2:[2]
Assuming you are using latest version of driver, https://github.com/godror/godror
sql.Open("godror", params.StringWithPassword())
implies standaloneConnection=0 setting.
The stats you are seeing is from go sql connection pool. The go sql calls the driver connect method which inturn tries to get connection from another pool (OCI maintains it due to setting standaloneConnection=0 ).
The max outbound connections hasn't exceeded the params.MaxSessions but its just the go sql connection counter
numOpen, ....
It is ideal you tune the go sql pool settings closer to another pool values so that the go routines just don't block.
You can check the OCI pool stats by using GetPoolStats() method from godror.Conn and confirm the real number of maximum outbound connections. example here
https://github.com/godror/godror/blob/main/z_test.go
Solution 3:[3]
DB In Use Conn: 242 DB Max Idle Closed: 766
The sum is almost 1000, like the value of this default
poolMaxSessions=1000
I think you don’t have 242 simultaneous connections in use. You have a pull of connections and the database will limit the number of simultaneous sessions.
You should check how the sql package handles it (it is open source!) and how the specific driver handles it (also open source!) and if necessary open an issue on the driver project
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | rustyhu |
| Solution 2 | |
| Solution 3 | Tiago Peczenyj |