use a try/except instead

Author: ngoldbaum

src/pytest_run_parallel/plugin.py

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

@@ -117,8 +117,7 @@ def visit_Assign(self, node):
                 self.generic_visit(node)
 
 
-@functools.lru_cache
-def identify_thread_unsafe_nodes(fn, skip_set, level=0):
+def _identify_thread_unsafe_nodes(fn, skip_set, level=0):
     if is_hypothesis_test(fn):
         return True, "uses hypothesis"
     try:
@@ -131,6 +130,17 @@ def identify_thread_unsafe_nodes(fn, skip_set, level=0):
     return visitor.thread_unsafe, visitor.thread_unsafe_reason
 
 
+cached_thread_unsafe_identify = functools.lru_cache(_identify_thread_unsafe_nodes)
+
+
+def identify_thread_unsafe_nodes(fn, skip_set, level=0):
+    try:
+        return cached_thread_unsafe_identify(fn, skip_set, level=level)
+    except TypeError:
+        # skip caching if we hit an error about fn not being hashable
+        return _identify_thread_unsafe_nodes(fn, skip_set, level=level)
+
+
 class ThreadComparator:
     def __init__(self, n_threads):
         self._barrier = threading.Barrier(n_threads)