Concurrent piped I/O hanging indefinitely

[tdb-alcorn]

In this Stack Overflow question, we found that the problem experienced occurs in the Scastie playground but not locally.

i.e. this code hangs indefinitely:

import java.io._
import scala.io.Source
import scala.concurrent._
import scala.concurrent.ExecutionContext.Implicits.global

def copy(inputStream: InputStream, outputStream: OutputStream): Unit = {
  val buffer = new Array[Byte](1024)
  var bytesRead = inputStream.read(buffer)
  while (bytesRead != -1) {
    outputStream.write(buffer, 0, bytesRead)
    bytesRead = inputStream.read(buffer)
  }
  outputStream.flush()
}

val os0 = new PipedOutputStream
val is0 = new PipedInputStream(os0)

val os1 = new PipedOutputStream
val is1 = new PipedInputStream(os1)

// write to os0
Future {
  os0.write(("foobarbaz"*1000).getBytes("utf-8"))
  os0.close()
}

// copy is0 to os1
Future {
  copy(is0, os1)
  os1.close()
}

// read is1 to output
val result = Source.fromInputStream(is1).mkString
println(result)

Does scastie handle Futures / multiple threads in some unusual way?