The PreparedStatement allocated here:

and the ResultSet allocated here:

are leaked because close is never called. Calling close is a requirement of JDBC and some drivers (e.g. pgjdbc-ng) rely on this resource cleanup to keep memory usage optimized.

I was using the smallest of tests while debugging an issue logged against the pgjdbc-ng driver so I cannot say this is the extent of the leaks; looking through the codebase it appears there may be quite a few more leaks similar to these.

Here was my simple test:

    val db = Database.connect(
        "jdbc:pgsql://localhost/test",
        user = "test",
        password = "test",
        driver = "com.impossibl.postgres.jdbc.PGDriver"
    )

    transaction(db) {

        for (i in 0 until 100000) {
            TestTable
                .selectAll()
                .map { Test(it[id], it[name], [bin]) }
        }

    }

FYI, I ran with the pgjdbc-ng driver and -Xmx256m to help force GC which triggers the driver's internal leak housekeeper to report leaks.