test1.txt

The error you're encountering is a "Communications link failure" in your MySQL JDBC connection. This suggests an issue with the communication link between your application and the MySQL server. Here are some steps to troubleshoot:

1. **Check MySQL Server Status:**
   Ensure that your MySQL server is running and reachable. Verify its status and network connectivity.

2. **Connection Settings:**
   Double-check the connection settings in your application's configuration files. Ensure that the hostname, port, username, password, and other connection parameters are correct.

3. **Firewall and Network Issues:**
   Ensure that there are no firewall issues blocking the communication between your application and the MySQL server. Verify that the network allows traffic on the specified port.

4. **MySQL Server Logs:**
   Examine the MySQL server logs for any error messages or additional details regarding the communication failure. This can provide insights into the root cause.

5. **Database Server Resources:**
   Check if the MySQL server has enough resources (CPU, memory) available. A server with insufficient resources might cause connection failures.

6. **Connection Pooling Configuration:**
   If you are using connection pooling (such as HikariCP in your stack trace), review its configuration. Adjust the pool settings based on your application's requirements.

7. **Test Connection Manually:**
   Try connecting to the MySQL server manually using a MySQL client or command-line tool with the same credentials your application uses. This can help identify if the issue is specific to your application.

8. **Driver Compatibility:**
   Ensure that the MySQL Connector/J version used in your application is compatible with both your application and the MySQL server version.

By systematically checking these aspects, you should be able to identify and resolve the communication link failure issue.