dpctl.tensor.Device keeps and uses cache for mapping unpartitioned devices to queues

As a result of this `X = dpt.empty((10,), device="gpu")` and `Y=dpt.empty((10,), device="gpu")`
would have the same associated queue, i.e. `X.sycl_queue is Y.sycl_queue` would give True

Author: oleksandr-pavlyk

dpctl/tensor/_device.py

@@ -29,6 +29,8 @@ class Device:
     or ``sycl_device``.
     """
 
+    __device_queue_map__ = dict()
+
     def __new__(cls, *args, **kwargs):
         raise TypeError("No public constructor")
 
@@ -55,7 +57,9 @@ def create_device(cls, dev):
         elif isinstance(dev, dpctl.SyclDevice):
             par = dev.parent_device
             if par is None:
-                obj.sycl_queue_ = dpctl.SyclQueue(dev)
+                if dev not in cls.__device_queue_map__:
+                    cls.__device_queue_map__[dev] = dpctl.SyclQueue(dev)
+                obj.sycl_queue_ = cls.__device_queue_map__[dev]
             else:
                 raise ValueError(
                     "Using non-root device {} to specify offloading "
@@ -64,9 +68,12 @@ def create_device(cls, dev):
                 )
         else:
             if dev is None:
-                obj.sycl_queue_ = dpctl.SyclQueue()
+                _dev = dpctl.SyclDevice()
             else:
-                obj.sycl_queue_ = dpctl.SyclQueue(dev)
+                _dev = dpctl.SyclDevice(dev)
+            if _dev not in cls.__device_queue_map__:
+                cls.__device_queue_map__[_dev] = dpctl.SyclQueue(_dev)
+            obj.sycl_queue_ = cls.__device_queue_map__[_dev]
         return obj
 
     @property