We are using spring data cassandra, when connection to cassandra is lost, spring data logs that it is retrying connection, but when repository is called no exception is thrown ?, is there a way to check if the connection is disconnected.
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I have some client class to external data provider.
In this class, I'm using webclient reactive client and crud repository.
Webclient uses repo to save responses from client (business requirement). For instance in onError, onStatus etc methods uses this repository. We performed load tests and it's working well.
The problem is when external API is not working and we're retrying couple of times (exponential backoff). Then I get:
HikariPool-1 - Connection is not available, request timed out after 30005ms
org.springframework.dao.DataAccessResourceFailureException: Unable to acquire JDBC Connection; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection
So it seems like webclient is keeping connection while retrying for 30 seconds and we're running out of connections. Extending connection pool size is not the way I want to fix that.
Is there any way to release connection while webclient is jsut waiting for another retry and so on?
My application say,
Error querying database. Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections
But DB connection is not full.
I use spring and mybatis and mariaDB. what is the problem?
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I am using spring data jpa and hikari connection pooling. In repository file, I am using methods to connect to database. I would like to know how and where to close the database connections.
Repository
public interface abc extends JPARepository<abc, int>{
List<abc> findById(int id);}
Any help on how to close the connections and where(service layer or repository) would be really appreciated
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With Connection Pooling, using the framework, The task of creating a connection before each operation and closing the connection after the operation is now taken from the programmer and transferred to the Spring Context:-
The application requests a connection from the connection pool.
If an unused connection exists, it is returned by the pool; otherwise, the pool creates a new connection.
The application sends a query to the Hybrid Data Pipeline connectivity service.
The application obtains query results.
The application displays the result to the end-user.
The application closes the connection, which returns the connection to the pool.
Note: The application calls the close() method, which allows the connection to remain open. The pool receives the notification of the close request.
In my web application I am using hibernate & spring. The Hibernate SessionFactory object is being injected as a spring bean at the time of tomcat server start up. Normally it is working fine. But the problem arises when I shut down or even restart my database.
After restarting my database if I retrieve a session from Hibernate SessionFactory object and want to execute query i am getting org.hibernate.exception.JDBCConectionException: Could not execute query exception.
To overcome this problem I need to restart the tomcat server. After restart it creates the new SessionFactory object, so I don’t get the exception.
In a situation how can I get a new fresh connection with the database, so that I don’t need to restart the server again & again.
SessionFactory rebuild worked for me
Our app is using tomcat, hibernate(3.5.1) and Oracle db (there are actualy two instances - one is the main for the application and the second one - remote)
sometimes remote db restarts, after that exception occurs on each call
JDBCConnectionException:could not execute query
Caused by: SQLRecoverableException: No more data to read from socket
Fistly I added to configuration
hibernate.dbcp.validationQuery=select 1 from dual
hibernate.dbcp.testOnBorrow=true
hibernate.dbcp.testOnReturn=true
but without result.
Then I tried to close sessions and recreate it.
Finally what worked for me - after this exeption
sessionFactory recreate
sessionFactory.close();
sessionFactory = annotationConfiguration.buildSessionFactory();
This is not really Spring or Hibernate related. What you need to do is to setup your JDBC connection pool to test connections before returning them to whoever needs them (e.g. Hibernate). If the pool discovers that the connection in the pool is broken, it dicards it and tries another one from the pool. If all connections in the pool are broken, the pool will try to create new ones. Everything is transparent and your application won't even notice.
Which connection pool you use? In dbcp set validationQuery to"SELECT 1" nd consider setting: testOnBorrow=true, testOnReturn=true and testWhileIdle=true. For c3p0 check out the documentation.
I was wondering is there any way in Java to force a stale connection?
We have some logic that determines if a sqlexception received is actually a Stale Connection - if it is we try and reconnect to the database.
I could not find any objects that could be mocked (using EasyMock or Powermock) in order to similulate a stale connection so I was there any properties we can set on the connection cache to expire a connection?