Monitor runs in 2 threads - _Thread 1_ is main thread, which initializes all components (logger, ...), starts the other thread and runs the ZeroMQ part of the application - receives and parses incomming messages from broker and forwards them to _thread 2_ sending logic. _Thread 2_ is responsible for managing all of WebSocket connections asynchronously. Whole thread is one big _asyncio_ event loop through which are processed all actions. None of custom data types is thread-safe, so all events from other threads (actually only `send_message` method) must be called within the event loop (via `asyncio.loop.call_soon_threadsafe` function). Please note, that most of the Python interpreter use GIL ([Global Interpreter Lock](https://wiki.python.org/moin/GlobalInterpreterLock)), so there is actualy no parallelism in the performance point of view, but proper synchronization is still required!
Martin Polanka
8 years ago