DJE-012 Warning Performance

Broadcast storm from push_to_view per keystroke

Error message

Application becomes unresponsive with multiple connected clients

Calling push_to_view() on every keystroke (e.g., in a collaborative editor) causes N full re-renders for N connected clients on every key press. This creates a broadcast storm that overwhelms both the server and connected browsers.

broadcast bug-fixed performance websocket

Affected versions: >=0.2.0

Solution

Before (problematic)

class NoteEditor(LiveView):
    def handle_event(self, event, params):
        if event == "update_content":
            self.content = params["content"]
            # BAD: Broadcasts full re-render to ALL clients
            self.push_to_view("note_channel")

After (fixed)

class NoteEditor(LiveView):
    _skip_broadcast = False

    def handle_event(self, event, params):
        if event == "update_content":
            self.content = params["content"]
            self._skip_broadcast = True
            self._broadcast("note_channel", {
                "content": self.content
            })

    def _on_broadcast(self, channel, data):
        self.content = data["content"]

Back to Error Reference