Http4sCatsEffectServer.scala

package example

import cats.effect.{ExitCode, IO, IOApp}
import org.http4s.HttpRoutes
import org.http4s.dsl.Http4sDsl
import org.http4s.server.blaze.BlazeServerBuilder
import org.http4s.implicits._

import scala.concurrent.ExecutionContext

object Http4sCatsEffectServer extends IOApp {

  override def run(args: List[String]): IO[ExitCode] = {

    val httpApp = {
      object dsl extends Http4sDsl[IO]
      import dsl._

      HttpRoutes.of[IO] {
        case GET -> Root => Ok("Hello, World!")
      }
    }.orNotFound

    val server =
      BlazeServerBuilder[IO](ExecutionContext.global)
        .bindHttp(8080, "0.0.0.0")
        .withHttpApp(httpApp)
        .resource

    server.use(_ => IO.never).as(ExitCode.Success)
  }
}

Http4sZioServer.scala

package example

import org.http4s.HttpRoutes
import org.http4s.dsl.Http4sDsl
import org.http4s.implicits._
import org.http4s.server.blaze.BlazeServerBuilder
import zio.internal.Platform
import zio.interop.catz._
import zio.interop.catz.implicits._
import zio.{ExitCode, Task, URIO}

import scala.concurrent.ExecutionContext

object Http4sZioServer extends CatsApp {

  override val platform: Platform =
    Platform.benchmark

  override def run(args: List[String]): URIO[zio.ZEnv, ExitCode] = {

    val httpApp = {
      object dsl extends Http4sDsl[Task]
      import dsl._

      HttpRoutes.of[Task] {
        case GET -> Root => Ok("Hello, World!")
      }
    }.orNotFound

    val server =
      BlazeServerBuilder[Task](ExecutionContext.global)
        .bindHttp(8081, "0.0.0.0")
        .withHttpApp(httpApp)
        .resource

    server.toManaged.useForever
      .catchAll(err => zio.console.putStrLn(s"Error: $err").as(ExitCode.failure))
      .as(ExitCode.success)
  }
}

wrk.txt

For `Http4sCatsEffectServer`, after warming up with two earlier runs:

$ wrk -c16 -t2 -d1m http://localhost:8080/
Running 1m test @ http://localhost:8080/
  2 threads and 16 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency   390.85us    1.56ms  69.00ms   99.32%
    Req/Sec    23.87k     2.46k   31.47k    80.33%
  2850186 requests in 1.00m, 353.36MB read
Requests/sec:  47456.01
Transfer/sec:      5.88MB

For `Http4sZioServer`, after warming up with two earlier runs:

$ wrk -c16 -t2 -d1m http://localhost:8081/
Running 1m test @ http://localhost:8081/
  2 threads and 16 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     1.76ms  574.61us  12.74ms   78.34%
    Req/Sec     4.58k   424.11     5.28k    63.83%
  546776 requests in 1.00m, 67.79MB read
Requests/sec:   9112.45
Transfer/sec:      1.13MB

Hardware:

MBP (2018): i9 @ 2.9 GHz * 6 cores; 32 GB RAM