Demonstration for not closing c3p0 connections after junit tests
Up to c3p0 Version 0.9.0.4 close() worked as expected.
Since c3p0 Version 0.9.1 connections do not get closed.
This uses Java8, Springframework 2.5.6 and Hibernate 3.
Yes, this is out-dated, but its only to demonstrate the issue with the close().
The example expects a MariaDB at localhost:3306 with the following settings:
Database: exampledb
Username: exampleuser
Password: examplepassword
This can be modified in the file src/main/resources/applicationContext.xml
Database and user can be created with the following SQL statements:
CREATE DATABASE `exampledb`
CREATE USER IF NOT EXISTS 'exampleuser'@'localhost' IDENTIFIED BY 'examplepassword';
GRANT ALL ON `exampledb`.* TO 'exampleuser'@'localhost';
Run the JUnit Test ExampleTest via mvn test or in the IDE of your choice.
View the MariaDB Logfile, it shows something like:
Aborted connection 70 to db: 'exampledb' user: 'exampleuser' host: 'localhost' (Got an error reading communication packets)
Aborted connection 71 to db: 'exampledb' user: 'exampleuser' host: 'localhost' (Got an error reading communication packets)
Aborted connection 72 to db: 'exampledb' user: 'exampleuser' host: 'localhost' (Got an error reading communication packets)
BasicResourcePool spawns a Thread for cleanup:
new Thread("Resource Destroyer in BasicResourcePool.close()")
In private void destroyResource(final Object resc, boolean synchronous, final boolean checked_out) a class DestroyResourceTask implements Runnable shall be instantiated and executed, but this never happens. And so, the connections get not closed cleanly, leading to the MariaDB log.