Slick 5ms overhead when querying "SELECT 1" from MySQL

Trying to understand if I’m doing something wrong here, but I’m getting 5ms of overhead for each slick stream I’m creating. The query itself takes 1ms to run SELECT 1 which does nothing server side, the connection is to local host, and the configuration uses a connection pool.

Here is the full example:

import akka.actor.ActorSystem
import akka.stream.alpakka.slick.scaladsl.{Slick, SlickSession}
import akka.stream.scaladsl.Sink
import com.typesafe.config.ConfigFactory
import org.scalatest.funsuite.AnyFunSuite
import slick.jdbc.MySQLProfile.api._
import slick.jdbc.{MySQLProfile, SQLActionBuilder, SetParameter}

import scala.concurrent.Await
import scala.concurrent.duration.DurationInt
import scala.jdk.CollectionConverters._

class SlickTest extends AnyFunSuite
{
    implicit lazy val system: ActorSystem = ActorSystem()

    test("Doing nothing for 5ms")
    {
        implicit lazy val session: SlickSession = {
            val settings = Map(
                "slick.connectionPool" -> "HikariCP",
                "slick.driver" -> "com.mysql.cj.jdbc.Driver",
                "slick.url" -> *,
                "slick.user" -> *,
                "slick.password" -> *,
                "slick.numThreads" -> 10
            )
            val config = ConfigFactory.parseMap(settings.asJava)
            val db = Database.forConfig("slick", config)
            val session: SlickSession = SlickSession.forDbAndProfile(db, MySQLProfile)
            system.registerOnTermination(() => session.close())
            session
        }

        (0 to 30).foreach { _ =>
            System.out.println(s"BEGIN: " + System.currentTimeMillis())
            val sql = SQLActionBuilder("SELECT 1", SetParameter.SetUnit)
            val superExpensiveQuery = Slick.source(sql.as[Int])
            Await.result(superExpensiveQuery.runWith(Sink.ignore), 10.seconds)
            System.out.println(s"END: " + System.currentTimeMillis())
        }
    }
}

From the tail end of that test here is what is logged:

BEGIN: 1666075622643
[18/10/2022 06:47:02.644] [DEBUG] [slick.basic.BasicBackend.stream] Signaling onSubscribe(slick.jdbc.JdbcBackend$JdbcStreamingActionContext@603305da)
[18/10/2022 06:47:02.644] [DEBUG] [slick.basic.BasicBackend.action] #1: StreamingResultAction [SELECT 1]
[18/10/2022 06:47:02.644] [DEBUG] [slick.basic.BasicBackend.stream] Starting initial streaming action, realDemand = 16
[18/10/2022 06:47:02.644] [DEBUG] [slick.jdbc.JdbcBackend.statement] Preparing statement: SELECT 1
[18/10/2022 06:47:02.645] [DEBUG] [slick.jdbc.JdbcBackend.statement] Executing prepared statement: HikariProxyPreparedStatement@1983378226 wrapping com.mysql.cj.jdbc.ClientPreparedStatement: SELECT 1
[18/10/2022 06:47:02.645] [DEBUG] [s.j.J.statementAndParameter] Executing prepared statement: HikariProxyPreparedStatement@1983378226 wrapping com.mysql.cj.jdbc.ClientPreparedStatement: SELECT 1
[18/10/2022 06:47:02.647] [DEBUG] [slick.jdbc.JdbcBackend.benchmark] Execution of prepared statement took 2ms
[18/10/2022 06:47:02.648] [DEBUG] [slick.jdbc.StatementInvoker.result] /---\
[18/10/2022 06:47:02.648] [DEBUG] [slick.jdbc.StatementInvoker.result] | 1 |
[18/10/2022 06:47:02.648] [DEBUG] [slick.jdbc.StatementInvoker.result] | 1 |
[18/10/2022 06:47:02.648] [DEBUG] [slick.jdbc.StatementInvoker.result] |---|
[18/10/2022 06:47:02.648] [DEBUG] [slick.jdbc.StatementInvoker.result] | 1 |
[18/10/2022 06:47:02.648] [DEBUG] [slick.jdbc.StatementInvoker.result] \---/
[18/10/2022 06:47:02.648] [DEBUG] [slick.basic.BasicBackend.stream] Signaling onComplete()
[18/10/2022 06:47:02.648] [DEBUG] [slick.basic.BasicBackend.stream] Sent up to 16 elements - Stream completely delivered
[18/10/2022 06:47:02.648] [DEBUG] [slick.basic.BasicBackend.stream] Finished streaming action
END: 1666075622648
BEGIN: 1666075622648
[18/10/2022 06:47:02.649] [DEBUG] [slick.basic.BasicBackend.stream] Signaling onSubscribe(slick.jdbc.JdbcBackend$JdbcStreamingActionContext@3163f88a)
[18/10/2022 06:47:02.650] [DEBUG] [slick.basic.BasicBackend.action] #1: StreamingResultAction [SELECT 1]
[18/10/2022 06:47:02.650] [DEBUG] [slick.basic.BasicBackend.stream] Starting initial streaming action, realDemand = 16
[18/10/2022 06:47:02.650] [DEBUG] [slick.jdbc.JdbcBackend.statement] Preparing statement: SELECT 1
[18/10/2022 06:47:02.651] [DEBUG] [slick.jdbc.JdbcBackend.statement] Executing prepared statement: HikariProxyPreparedStatement@905949325 wrapping com.mysql.cj.jdbc.ClientPreparedStatement: SELECT 1
[18/10/2022 06:47:02.651] [DEBUG] [s.j.J.statementAndParameter] Executing prepared statement: HikariProxyPreparedStatement@905949325 wrapping com.mysql.cj.jdbc.ClientPreparedStatement: SELECT 1
[18/10/2022 06:47:02.653] [DEBUG] [slick.jdbc.JdbcBackend.benchmark] Execution of prepared statement took 1ms
[18/10/2022 06:47:02.654] [DEBUG] [slick.jdbc.StatementInvoker.result] /---\
[18/10/2022 06:47:02.654] [DEBUG] [slick.jdbc.StatementInvoker.result] | 1 |
[18/10/2022 06:47:02.654] [DEBUG] [slick.jdbc.StatementInvoker.result] | 1 |
[18/10/2022 06:47:02.654] [DEBUG] [slick.jdbc.StatementInvoker.result] |---|
[18/10/2022 06:47:02.654] [DEBUG] [slick.jdbc.StatementInvoker.result] | 1 |
[18/10/2022 06:47:02.654] [DEBUG] [slick.jdbc.StatementInvoker.result] \---/
[18/10/2022 06:47:02.654] [DEBUG] [slick.basic.BasicBackend.stream] Signaling onComplete()
[18/10/2022 06:47:02.654] [DEBUG] [slick.basic.BasicBackend.stream] Sent up to 16 elements - Stream completely delivered
[18/10/2022 06:47:02.654] [DEBUG] [slick.basic.BasicBackend.stream] Finished streaming action
END: 1666075622654

I’ve got PHP drivers that run that in well under 1ms. Any thoughts?

Thanks,
Terence