HikariCP Shutdown Issue in Spring Boot

Spring Boot HikariCP Shutdown: Preventing Early Shutdown Errors

Spring Boot's HikariCP connection pool can throw java.lang.IllegalStateException: Connection pool shut down if connections are still in use during shutdown. This occurs because HikariCP gracefully closes, but active connections prevent immediate termination.

Solution: Increase the shutdown timeout. HikariCP provides spring.datasource.hikari.shutdown-timeout (in milliseconds) to extend the graceful shutdown period. This allows outstanding connections to complete before pool closure.

Example application.yml:

spring:
  datasource:
    hikari:
      shutdown-timeout: 30000 # 30 seconds

Code Example (Java config):

@Configuration
public class DataSourceConfig {
    @Bean
    public DataSource dataSource(DataSourceProperties properties) {
        HikariConfig config = properties.getHikariConfig();
        config.setShutdownTimeout(30000); // 30 seconds
        return new HikariDataSource(config);
    }
}

Troubleshooting:

If the error persists, investigate:

• Long-running transactions: Ensure transactions are properly managed and don't hold connections unnecessarily.
• Connection leaks: Identify and fix any code that fails to close connections. Use try-with-resources for automatic closure.
• Insufficient timeout: Increase shutdown-timeout further if necessary. Observe application shutdown logs for connection details.

By adjusting the shutdown timeout and addressing potential connection leaks, you can prevent HikariCP's premature shutdown errors in your Spring Boot application.