use an lru_cache to speed up recursive ast parsing

Author: ngoldbaum

src/pytest_run_parallel/plugin.py

@@ -172,7 +172,8 @@ def pytest_itemcollected(item):
     skipped_functions = [
         x.split(".") for x in item.config.getini("thread_unsafe_functions")
     ]
-    skipped_functions = {(".".join(x[:-1]), x[-1]) for x in skipped_functions}
+    skipped_functions = frozenset((".".join(x[:-1]), x[-1]) for x in
+                                  skipped_functions)
 
     if n_workers > 1:
         thread_unsafe, thread_unsafe_reason = identify_thread_unsafe_nodes(

src/pytest_run_parallel/utils.py

@@ -1,4 +1,5 @@
 import ast
+import functools
 import inspect
 import threading
 import types
@@ -116,6 +117,7 @@ def visit_Assign(self, node):
                 self.generic_visit(node)
 
 
+@functools.lru_cache
 def identify_thread_unsafe_nodes(fn, skip_set, level=0):
     if is_hypothesis_test(fn):
         return True, "uses hypothesis"