Getting ORA-02391: SESSIONS_PER_USER limit - database

Question

Is there a query which I can use to grab the amount of sessions I can use concurrently? I am threading some database connections and getting the error:
ORA-02391: exceeded simultaneous SESSIONS_PER_USER limit
How can I get the value for this limit?

Answer 1

start with this query to find out how many sessions you are using
select count(*) from v$session where username='YourUser';
then find out how many you are allowed in the profile for your user
select profile from dba_users where username ='YourUser';
finally
select PROFILE, LIMIT
from dba_profiles
WHERE RESOURCE_NAME = 'SESSIONS_PER_USER'
AND PROFILE = 'YourUserProfile';
and the fix
Alter profile YourUserProfile limit SESSIONS_PER_USER 100;
Limits are in place for a reason as each session consumes resources. If you increase the limit some careful planning is in order for production systems so you don't run out of memory.

Answer 2

It's profile setting
SELECT * FROM DBA_PROFILES WHERE RESOURCE_NAME = 'SESSIONS_PER_USER';
You can change it using
ALTER PROFILE <profile name> LIMIT SESSIONS_PER_USER <number>;
or
ALTER PROFILE <profile name> LIMIT SESSIONS_PER_USER UNLIMITED;

Answer 3

Get the PROFILE for that user
select profile from dba_users where username = :who;
Then get the resource limit for that profile
SELECT P1.LIMIT AS "Concurrent Sessions (Per User)"
FROM DBA_PROFILES P1
WHERE P1.PROFILE = :PROFILE
AND P1.RESOURCE_NAME = 'SESSIONS_PER_USER';
Or
In SQL Developer, open the DBA panel and browse the users & profiles under 'security'

Answer 4

While the other solutions provide statements on altering the user session limit, the diagnostic queries did not work for me, although I am a complete beginner and maybe performed it incorrectly. The following queries from Atlassian helped me.
For checking number of sessions per user, so you can see which users are nearing their limit:
SELECT count(*) as connections,
username
FROM v$session
GROUP BY username
ORDER BY username;
and to check what that limit is set to be:
SELECT DISTINCT username,
profile,
resource_name,
limit
FROM dba_profiles
NATURAL JOIN dba_users
WHERE resource_name = 'SESSIONS_PER_USER';
From there, the rest of the linked site or other solutions here can presumably help with altering the limit to your needs.