update release connection

models/GpsTracksModels.js

@@ -440,6 +440,7 @@ class GpsTracksModels {
 						if (trackLock) {
 							await rltmMutex.unlock(trackLock)
 						}
+						conn.release();
 					}
 				}
 
@@ -528,6 +529,7 @@ class GpsTracksModels {
 						console.log("ERROR unlock mutex : " + rltm.device_id, unlockErr)
 					}
 				}
+				conn.release(); // release connection
 			}
 		})
 	}