Connection leak detected by HikariPool LeakDetectionThreshold

I have Hikari Connection Pool, And configured as below

 HikariConfig hikariConfig = new HikariConfig(); hikariConfig.setJdbcUrl(dbProps.getUrl()); hikariConfig.setUsername(dbProps.getUser()); hikariConfig.setPassword(dbProps.getPass()); hikariConfig.addDataSourceProperty("cachePrepStmts", "true"); hikariConfig.addDataSourceProperty("prepStmtCacheSize", "250"); hikariConfig.addDataSourceProperty("prepStmtCacheSqlLimit", "2048"); hikariConfig.setMaximumPoolSize(Runtime.getRuntime().availableProcessors() * 5 + 2); hikariConfig.setIdleTimeout(36000); hikariConfig.setConnectionTestQuery("SELECT 1;"); hikariConfig.setConnectionTimeout(20000); hikariConfig.setMaxLifetime(1440000); hikariConfig.setLeakDetectionThreshold(3000); // LEAK DETECTION THRESHOLD dataSource = new HikariDataSource(hikariConfig);

And Some DB details is fetched as below :

public class SomeDBFetcher {
private DataSource dataSource;
public SomeDBFetcher(final DataSource dataSource) { this.dataSource = dataSource;
}
public void someMethod() { try (final var conn = dataSource.getConnection(); // CONNECTION LEAKS ? final var stmt = conn.prepareStatement("SOME QUERY")) { // SOME DB }
}

}

In the logs , I am seeing connection leaks. Why connection leaks is happening?

1 Answer

LeakDetectionThreshold informs about potential leaks when you don't close your connection in defined limit of time - in your case it's 3s.

Here probably you have query (or something inside try clause) that takes longer than 3 seconds, and Hikari warns you about potential connection leak.

So if you see such a warning, it doesn't necessarily mean you actually have a leak.

From documentation:

leakDetectionThreshold
This property controls the amount of time that a connection can be out of the pool before a message is logged indicating a possible connection leak. A value of 0 means leak detection is disabled. Lowest acceptable value for enabling leak detection is 2000 (2 seconds). Default: 0