Getting ORA-04021 - "timeout occurred while waiting to lock object" in EAP7

Issue

When it tried to connect production database using read only user at our end we were not able to connect it.
At the same time we were unable to login into online application.
After 10 min we got database connection through SQL developer and able to login in online application.
 
I have checked production logs for login issue, found below error:
 
Caused by: java.sql.SQLException: ORA-04021: timeout occurred while waiting to lock object
[ERROR] javax.resource.ResourceException: IJ000453: Unable to get managed connection for java:jboss/datasources/myDS
[WARN] SQL Error: 0, SQLState: null
[ERROR] javax.resource.ResourceException: IJ000453: Unable to get managed connection for java:jboss/datasources/myDS
 
Which means jboss application server getting a timeout while connecting to the DB server, hence we were getting issue in login.