make __copy__ methods in cache classes hold locks

Author: ndgrigorian

dpctl/_sycl_device_factory.pyx

@@ -445,7 +445,9 @@ cdef class _DefaultDeviceCache:
     def __copy__(self):
         cdef _DefaultDeviceCache _copy = _DefaultDeviceCache.__new__(
             _DefaultDeviceCache)
-        _copy._update_map(self.__device_map__)
+        # lock must be held to avoid race conditions on map state
+        with self._cache_lock:
+            _copy._update_map(self.__device_map__.copy())
         return _copy
 
 

dpctl/_sycl_queue_manager.pyx

@@ -73,7 +73,9 @@ cdef class _DeviceDefaultQueueCache:
         cdef _DeviceDefaultQueueCache _copy = _DeviceDefaultQueueCache.__new__(
             _DeviceDefaultQueueCache
         )
-        _copy._update_map(self.__device_queue_map__)
+        # lock must be held to avoid race conditions on map state
+        with self._cache_lock:
+            _copy._update_map(self.__device_queue_map__.copy())
         return _copy