Add an example sending chunked responses

[mfelsche]

FYI @redvers

Let me know if this example addresses your problem.

[redvers]

The issue as I understand it is that finished() is called by actor _ServerConnection here:

  be _receive_finished(request_id: RequestID) =>
    """
    Indicates that the last *inbound* body chunk has been sent to
    `_chunk`. This is passed on to the back end.
    """
    _backend.finished(request_id)

In your example, (Line 211-212):

    while true do
      let file_chunk = file.read(chunk_size)

All the Array[U8 val] iso's that you create will be new allocations and will never have any opportunity to be available for Garbage Collection until:

a. The loop has completed (In other words, the entire size of the file has to have been fully allocated to memory).
b. The _receive_finished() behaviour has terminated.

I don't think it solves the problem, as it still results in at least 4.7G of memory allocation for a 4.7G .iso file.

[redvers]

After receiving the completed request, we need to send the chunks across multiple behaviours to allow for GC to happen.

[mfelsche]

I solved that issue by delegating the actual file reading and sending to another actor