fix(imperative): fix persistent_cache

GitOrigin-RevId: 8f7bb5899f91c9350cb7dd9a3a4dffac29784d5d

imperative/python/megengine/__init__.py

@@ -93,7 +93,6 @@ _persistent_cache_impl_ins.reg()
 atexit.register(_full_sync)
 
 del _set_fork_exec_path_for_timed_func
-del _persistent_cache_impl_ins
 
 # subpackages
 import megengine.autodiff

imperative/python/src/helper.h

@@ -366,7 +366,7 @@ namespace detail {
             return true;
         }
         static handle cast(mgb::PersistentCache::Blob blob, return_value_policy /* policy */, handle /* parent */) {
-            return bytes((const char*)blob.ptr, blob.size);
+            return bytes((const char*)blob.ptr, blob.size).release();
         }
     };
 

imperative/python/src/tensor.cpp

@@ -421,8 +421,10 @@ PyObject* TensorWrapper::numpy() {
         }
         return np_val.release().ptr();
     }
-
-    auto&& hv = interpreter_for_py->get_value(m_tensor->m_handle.get());
+    auto&& hv = [&]() {
+        py::gil_scoped_release _;
+        return interpreter_for_py->get_value(m_tensor->m_handle.get());
+    }();
     auto arr = py::reinterpret_steal<py::array>(npy::ndarray_from_tensor(hv, npy::ShareType::TRY_SHARE));
     if (!arr) {
         PyErr_SetString(PyExc_ValueError, "tensor invalid");
@@ -492,7 +494,10 @@ PyObject* TensorWrapper::_dev_tensor(){
     if (m_tensor->m_trace_info.recording && !skip_tracing) {
         PyObject_SetAttrString(m_tensor->m_trace_info.trace_mixin_info, "data_read", py::cast(true).release().ptr());
     }
-    auto dev_tensor = interpreter_for_py->get_dev_tensor(m_tensor->m_handle.get());
+    auto dev_tensor = [&](){
+        py::gil_scoped_release _;
+        return interpreter_for_py->get_dev_tensor(m_tensor->m_handle.get());
+    }();
     return py::cast(dev_tensor).release().ptr();
 }