[Dy2Stat]Polish @to_static temporary file directory to speed up transformation (#47102)

* [Dy2Stat]Polish @to_static temporary file directory

* [Dy2Stat]Polish @to_static temporary file directory

* refine temp.name

* fix typo

* fix typo

python/paddle/fluid/dygraph/dygraph_to_static/utils.py

@@ -19,7 +19,8 @@ import copy
 import collections
 from paddle.utils import gast
 import inspect
-import os
+import os, sys
+import shutil
 import six
 import tempfile
 import textwrap
@@ -82,6 +83,7 @@ dygraph_class_to_static_api = {
     "PolynomialDecay": "polynomial_decay",
 }
 
+DEL_TEMP_DIR = True  # A flag to avoid atexit.register more than once
 FOR_ITER_INDEX_PREFIX = '__for_loop_var_index'
 FOR_ITER_TUPLE_PREFIX = '__for_loop_iter_tuple'
 FOR_ITER_TARGET_PREFIX = '__for_loop_iter_target'
@@ -546,6 +548,22 @@ def create_assign_node(name, node):
     return targets, assign_node
 
 
+def get_temp_dir():
+    """
+    Return @to_static temp directory.
+    """
+    dir_name = "paddle/to_static_tmp"
+    temp_dir = os.path.join(os.path.expanduser('~/.cache'), dir_name)
+    is_windows = sys.platform.startswith('win')
+    if is_windows:
+        temp_dir = os.path.normpath(temp_dir)
+
+    if not os.path.exists(temp_dir):
+        os.makedirs(temp_dir)
+
+    return temp_dir
+
+
 def ast_to_func(ast_root, dyfunc, delete_on_exit=True):
     """
     Transform modified AST of decorated function into python callable object.
@@ -553,27 +571,40 @@ def ast_to_func(ast_root, dyfunc, delete_on_exit=True):
     function, the other inner functions are invisible for the decorated function.
     """
 
-    def remove_if_exit(filepath):
-        if os.path.exists(filepath):
-            os.remove(filepath)
+    def remove_if_exit(dir_path):
+        if os.path.exists(dir_path):
+            shutil.rmtree(dir_path)
+
+    def func_prefix(func):
+        pre_fix = func.__name__
+        if hasattr(func, '__self__'):
+            try:
+                pre_fix = func.__self__.__class__.__name__ + '_' + func.__name__
+            except:
+                pass
+        return pre_fix
 
     source = ast_to_source_code(ast_root)
     source = _inject_import_statements() + source
-
+    temp_dir = get_temp_dir()
     f = tempfile.NamedTemporaryFile(mode='w',
+                                    prefix=func_prefix(dyfunc),
                                     suffix='.py',
                                     delete=False,
+                                    dir=temp_dir,
                                     encoding='utf-8')
     with f:
         module_name = os.path.basename(f.name[:-3])
         f.write(source)
 
-    if delete_on_exit:
-        atexit.register(lambda: remove_if_exit(f.name))
-        atexit.register(lambda: remove_if_exit(f.name[:-3] + ".pyc"))
+    global DEL_TEMP_DIR
+    if delete_on_exit and DEL_TEMP_DIR:
+        # Clear temporary files in TEMP_DIR while exitting Python process
+        atexit.register(remove_if_exit, dir_path=temp_dir)
+        DEL_TEMP_DIR = False
 
-    module = SourceFileLoader(module_name, f.name).load_module()
     func_name = dyfunc.__name__
+    module = SourceFileLoader(module_name, f.name).load_module()
     # The 'forward' or 'another_forward' of 'TranslatedLayer' cannot be obtained
     # through 'func_name'. So set the special function name '__i_m_p_l__'.
     if hasattr(module, '__i_m_p_l__'):