change mp spawn method

mp.Queue is not pickle-able, which prevents spawn method from working,
but is necessary for CUDA to work properly

src/__main__.py

@@ -13,15 +13,16 @@ logging.basicConfig(
     format="%(asctime)s %(name)-40s %(levelname)-8s %(message)s",
 )
 
+mp.set_start_method("spawn")
+
 
 class Receiver(NamedTuple):
     ip: ingest.Host
     receiver: ingest.FeitReceiver
-    queue: "mp.Queue[ingest.CSI]"
 
 
 receivers = [
-    Receiver(ip, ingest.FeitReceiver(ip), mp.Queue(config.SAMPLE_RATE))
+    Receiver(ip, ingest.FeitReceiver(ip, mp.Queue(config.SAMPLE_RATE)))
     for ip in config.RECEIVE_HOSTS
 ]
 
@@ -30,15 +31,15 @@ transmitter = ingest.FeitTransmitter()
 
 webapp_queue: "mp.Queue[aoa.AoA]" = mp.Queue(config.SAMPLE_RATE)
 
-processor = ingest.CSIProcessor({r.ip: r.queue for r in receivers}, webapp_queue)
+processor = ingest.CSIProcessor(
+    {r.ip: r.receiver.processing_queue for r in receivers}, webapp_queue
+)
 
 # Start webapp in background process
 webapp = mp.Process(target=visualise.start, args=(webapp_queue,))
 webapp.start()
 
-receiver_processes = [
-    mp.Process(target=r.receiver.listen, args=(r.queue,)) for r in receivers
-]
+receiver_processes = [mp.Process(target=r.receiver.listen) for r in receivers]
 
 for proc in receiver_processes:
     proc.start()

src/ingest.py

@@ -33,7 +33,7 @@ class FeitTransmitter:
 
 
 class FeitReceiver:
-    def __init__(self, host: Host):
+    def __init__(self, host: Host, processing_queue: "mp.Queue[CSI]"):
         self.host = host
         self.server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
         self.server.connect(host)
@@ -48,8 +48,9 @@ class FeitReceiver:
         self.logger = logging.getLogger(
             f"{__name__}.{self.__class__.__name__}-{self.host}"
         )
+        self.processing_queue = processing_queue
 
-    def listen(self, queue: "mp.Queue[CSI]"):
+    def listen(self):
         prev_time = datetime.now()
         while True:
             # This is the max size of a UDP packet. The size of the actual CSI
@@ -62,7 +63,7 @@ class FeitReceiver:
                     f"Received CSI data after {datetime.now() - prev_time}"
                 )
                 prev_time = datetime.now()
-                queue.put(csidata)
+                self.processing_queue.put(csidata)
             except struct.error:
                 self.logger.error("Failed to parse CSI data")