streams and memory usage

[morturo]

I have this code:
    
    
    proc pipeTo(input: Stream, output: Stream, chunkSize = 512) =
      var buff = repeat("\0", chunkSize)
      while true:
        let len = input.readDataStr(buff, 0..<chunkSize)
        if len == 0:
          break
        output.write(buff[0..<len])
        output.flush()
      
      echo buff.len
      output.close()
    
    
    proc downloadFile(client: HttpClient, fileItem: FileItem) =
      let outputDirPath = joinPath([paramStr(2), fileItem.album])
      let outputPath = joinPath([outputDirPath, fileItem.name])
      ensureDirExists(outputDirPath)
      
      let response = client.get(fileItem.url)
      let file = newFileStream(outputPath, fmWrite)
      
      response.bodyStream.pipeTo(file)
    
    
    Run

In theory, it should stream chunks of data between the network stream and the 
file stream, this way the memory usage should stay low. But something is wrong 
and it seems the entire file is inside the ram instead of being flushed to the 
disk.