put sessions = AudioUtilities.GetAllSessions() on another thread

volume.py

@@ -23,9 +23,11 @@ SLIDER_VALS = [
     }
 ]
 
+import time
 import math
 import subprocess
 from serial import Serial
+from threading import Thread
 from comtypes import CLSCTX_ALL
 from pycaw.pycaw import AudioUtilities, IAudioEndpointVolume, ISimpleAudioVolume
 
@@ -33,13 +35,21 @@ devices = AudioUtilities.GetSpeakers()
 interface = devices.Activate(IAudioEndpointVolume._iid_, CLSCTX_ALL, None)
 masterVolume = interface.QueryInterface(IAudioEndpointVolume)
 
+sessions = None
+
+def device_update_thread():
+    global sessions
+    while True:
+        sessions = AudioUtilities.GetAllSessions()
+        time.sleep(1)
+
 def setMasterVolume(num: int):
     if num < 0 or num > 100: return
     masterVolume.SetMasterVolumeLevelScalar((num/100), None)
 
 def setProgramVolume(num: int, program: str):
-    if num < 0 or num > 100: return    
-    sessions = AudioUtilities.GetAllSessions()
+    if num < 0 or num > 100: return
+    if sessions is None: return
     for session in sessions:
         volume = session._ctl.QueryInterface(ISimpleAudioVolume)
         if session.Process and session.Process.name() == program:
@@ -91,6 +101,9 @@ serial_ports()
 
 ser = Serial(SERIAL_PORT, SERIAL_BUAD_RATE)
 
+sessions_thread = Thread(target = device_update_thread)
+sessions_thread.start()
+
 while ser.is_open:
     cc=str(ser.readline())
     val = cc[2:][:-5].split('|')
@@ -101,3 +114,5 @@ while ser.is_open:
         case 1: # Slider
             level = (int(val[2])/1024)*100
             handle_slider(int(val[1]), level)
+
+sessions_thread.join()