stream: defer readable and flow when sync

Author: mafintosh

lib/_stream_readable.js

@@ -486,11 +486,18 @@ function onEofChunk(stream, state) {
   }
   state.ended = true;
 
-  // emit 'readable' now to make sure it gets picked up.
-  state.needReadable = false;
-  if (!state.emittedReadable) {
-    state.emittedReadable = true;
-    emitReadable_(stream);
+  if (state.sync && state.length) {
+    // if we are sync and have data in the buffer, wait until next tick
+    // to emit the data. otherwise we risk emitting data in the flow()
+    // the readable code triggers during a read() call
+    emitReadable(stream);
+  } else {
+    // emit 'readable' now to make sure it gets picked up.
+    state.needReadable = false;
+    if (!state.emittedReadable) {
+      state.emittedReadable = true;
+      emitReadable_(stream);
+    }
   }
 }