Very simple version of Isolates.

runtime/bin/io_service_patch.dart

Index: runtime/bin/io_service_patch.dart
diff --git a/runtime/bin/io_service_patch.dart b/runtime/bin/io_service_patch.dart
index c6a703529cf9fd67fe50451879e337ca6c48ae44..8f5a593055d923a75c26941b1f75f1a34000dbe4 100644
--- a/runtime/bin/io_service_patch.dart
+++ b/runtime/bin/io_service_patch.dart
@@ -30,13 +30,14 @@ patch class _IOService {
     }
     if (_receivePort == null) {
       _receivePort = new ReceivePort();
-      _replyToPort = _receivePort.toSendPort();
-      _receivePort.receive((data, _) {
+      _replyToPort = _receivePort.sendPort;
+      StreamSubscription subscription;
+      subscription = _receivePort.listen((data) {

[Ivan Posva, 2013/10/24 06:48:38]

This is one of those occasions where I would expect you to use the
RawReceivePort as you do not want to have to deal with streams, zones or
anything else when delivering the raw IO events from epoll to the IO subsystem.

[floitsch, 2013/10/24 16:15:58]

just wasn't changed back yet.
done.

         assert(data is List && data.length == 2);
         _messageMap.remove(data[0]).complete(data[1]);
         if (_messageMap.length == 0) {
           _id = 0;
-          _receivePort.close();
+          subscription.cancel();
           _receivePort = null;
         }
       });