bpo-31370: Remove support for threads-less builds (#3385)

* Remove Setup.config
* Always define WITH_THREAD for compatibility.

1 files changed, 6 insertions, 32 deletions

diff --git a/Lib/threading.py b/Lib/threading.py
index 06dbc68283..e4bf974495 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -990,38 +990,12 @@ class Thread:
 
     def _delete(self):
         "Remove current thread from the dict of currently running threads."
-
-        # Notes about running with _dummy_thread:
-        #
-        # Must take care to not raise an exception if _dummy_thread is being
-        # used (and thus this module is being used as an instance of
-        # dummy_threading).  _dummy_thread.get_ident() always returns 1 since
-        # there is only one thread if _dummy_thread is being used.  Thus
-        # len(_active) is always <= 1 here, and any Thread instance created
-        # overwrites the (if any) thread currently registered in _active.
-        #
-        # An instance of _MainThread is always created by 'threading'.  This
-        # gets overwritten the instant an instance of Thread is created; both
-        # threads return 1 from _dummy_thread.get_ident() and thus have the
-        # same key in the dict.  So when the _MainThread instance created by
-        # 'threading' tries to clean itself up when atexit calls this method
-        # it gets a KeyError if another Thread instance was created.
-        #
-        # This all means that KeyError from trying to delete something from
-        # _active if dummy_threading is being used is a red herring.  But
-        # since it isn't if dummy_threading is *not* being used then don't
-        # hide the exception.
-
-        try:
-            with _active_limbo_lock:
-                del _active[get_ident()]
-                # There must not be any python code between the previous line
-                # and after the lock is released.  Otherwise a tracing function
-                # could try to acquire the lock again in the same thread, (in
-                # current_thread()), and would block.
-        except KeyError:
-            if 'dummy_threading' not in _sys.modules:
-                raise
+        with _active_limbo_lock:
+            del _active[get_ident()]
+            # There must not be any python code between the previous line
+            # and after the lock is released.  Otherwise a tracing function
+            # could try to acquire the lock again in the same thread, (in
+            # current_thread()), and would block.
 
     def join(self, timeout=None):
         """Wait until the thread terminates.