To prevent a memory leak, the JDBC Driver has been forcibly unregistered
To prevent memory leaks with JDBC, it's crucial you deregister drivers as part of your shutdown routine:
This neat little routine loops through all your loaded JDBC drivers and deregisters every single one of them. This is your ticket out of resource-retentionville, especially in the land of servlet containers hot-redeploying applications.
The Nitty Gritty: Memory Leaks & JDBC Drivers
When you redeploy a web app, it's expected that the old version and its classes go gently into that good night. But if you have a JDBC driver, loaded up by your web application class loader, it registers itself with the DriverManager
and might not take the hint that it's time to leave. This stubbornness results in a memory leak, as previous deployment classes are left hanging with nowhere to go.
Best Practices for Dealing with JDBC Drivers
Dive into connection pooling
To manage your database connections in a more efficient and leak-proof manner, connection pools such as HikariCP or Tomcat JDBC Pool are highly recommended. Deploy these pools in the /lib
directory and be sure to put on your swimming trunks by setting them up correctly in the ServletContextListener
's contextInitialized()
.
Deploy the ServletContextListener cavalry
Implement a ServletContextListener
that wields the mighty power of manual deregistration in its contextDestroyed()
method. This relentless soldier ensures things get cleaned up properly whenever your web application is undeployed:
Put JDBC Drivers in their place: Tomcat's /lib directory
This makes DriverManager
believe the JDBC driver is associated with the system classloader rather than your specific webapp, reducing its chance of overstaying its welcome.
Keep your JDBC driver up-to-date
Like milk in your fridge, an outdated JDBC driver can result in something sour - so check for updates!
Handling Driver Deregistration
Manage shared drivers cautiously
Before you deregister a driver, remember others might be using it. Use the drivers.getClass().getClassLoader()
check to consider shared drivers.
Connection pools need closing too
Before attempting to deregister the drivers, all good pool parties must come to an end. Close your connection pools, folks!
Try-catch to handle potential troublemakers
Handle SQLExceptions
gracefully by employing try-catch blocks. Logs can tell great tales, perfect for helping with those debugging head-scratchers.
Nullify your data source references
Help out your garbage collector by setting data source references to null
.
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