Changelog updated to document PR #10641

changelog/10641.bugfix.rst

@@ -0,0 +1 @@
+Fix a race condition when creating or updating the stepwise plugin's cache, which could occur when multiple xdist worker nodes try to simultaneously update the stepwise plugin's cache.

src/_pytest/stepwise.py

@@ -49,6 +49,8 @@ def pytest_sessionfinish(session: Session) -> None:
     if not session.config.getoption("stepwise"):
         assert session.config.cache is not None
         if hasattr(session.config, "workerinput"):
+            # Do not update cache if this process is a xdist worker to prevent
+            # race conditions (#10641).
             return
         # Clear the list of failing tests if the plugin is not active.
         session.config.cache.set(STEPWISE_CACHE_DIR, [])
@@ -122,5 +124,7 @@ class StepwisePlugin:
 
     def pytest_sessionfinish(self) -> None:
         if hasattr(self.config, "workerinput"):
+            # Do not update cache if this process is a xdist worker to prevent
+            # race conditions (#10641).
             return
         self.cache.set(STEPWISE_CACHE_DIR, self.lastfailed)