             return r
         }
         set {
-            taskAttributesIsolation.async { self._priority = newValue }
+            taskAttributesIsolation.async(flags: .barrier) { self._priority = newValue }
         }
     }
     fileprivate var _priority: Float = URLSessionTaskPriorityDefault

        originalRequest = nil
        body = .none
        workQueue = DispatchQueue(label: "URLSessionTask.notused.0")
        taskAttributesIsolation = DispatchQueue(label: "URLSessionTask.notused.1")
        let fileName = NSTemporaryDirectory() + NSUUID().uuidString + ".tmp"
        _ = FileManager.default.createFile(atPath: fileName, contents: nil)
        self.tempFileURL = URL(fileURLWithPath: fileName)

            taskAttributesIsolation.sync { r = self._state }
            return r
        }
        set { taskAttributesIsolation.async(flags: .barrier) { self._state = newValue } }
    }
    fileprivate var _state: URLSessionTask.State = .suspended
    
