gh-64862: Use iter() with stop_exception in the stdlib

Lib/_weakrefset.py

@@ -52,14 +52,11 @@ def copy(self):
         return self.__class__(self)
 
     def pop(self):
-        while True:
-            try:
-                itemref = self.data.pop()
-            except KeyError:
-                raise KeyError('pop from empty WeakSet') from None
+        for itemref in iter(self.data.pop, stop_exception=KeyError):
             item = itemref()
             if item is not None:
                 return item
+        raise KeyError('pop from empty WeakSet')
 
     def remove(self, item):
         self.data.remove(ref(item))

Lib/concurrent/futures/thread.py

@@ -243,11 +243,8 @@ def _initializer_failed(self):
             self._broken = ('A thread initializer failed, the thread pool '
                             'is not usable anymore')
             # Drain work queue and mark pending futures failed
-            while True:
-                try:
-                    work_item = self._work_queue.get_nowait()
-                except queue.Empty:
-                    break
+            for work_item in iter(self._work_queue.get_nowait,
+                                  stop_exception=queue.Empty):
                 if work_item is not None:
                     work_item.future.set_exception(self.BROKEN(self._broken))
 
@@ -257,11 +254,8 @@ def shutdown(self, wait=True, *, cancel_futures=False):
             if cancel_futures:
                 # Drain all work items from the queue, and then cancel their
                 # associated futures.
-                while True:
-                    try:
-                        work_item = self._work_queue.get_nowait()
-                    except queue.Empty:
-                        break
+                for work_item in iter(self._work_queue.get_nowait,
+                                      stop_exception=queue.Empty):
                     if work_item is not None:
                         work_item.future.cancel()
 

Lib/importlib/_bootstrap.py

@@ -93,13 +93,9 @@ def clear(self):
         self.data = {}
 
     def _commit_removals(self):
-        pop = self._pending_removals.pop
         d = self.data
-        while True:
-            try:
-                key = pop()
-            except IndexError:
-                return
+        for key in iter(self._pending_removals.pop,
+                        stop_exception=IndexError):
             _weakref._remove_dead_weakref(d, key)
 
     def get(self, key, default=None):

Lib/multiprocessing/heap.py

@@ -257,11 +257,8 @@ def _remove_allocated_block(self, block):
 
     def _free_pending_blocks(self):
         # Free all the blocks in the pending list - called with the lock held.
-        while True:
-            try:
-                block = self._pending_free_blocks.pop()
-            except IndexError:
-                break
+        for block in iter(self._pending_free_blocks.pop,
+                          stop_exception=IndexError):
             self._add_free_block(block)
             self._remove_allocated_block(block)
 

Lib/multiprocessing/resource_tracker.py

@@ -310,11 +310,8 @@ def _ensure_running_and_write(self, msg=None):
             else:
                 self._launch()
 
-        while True:
-            try:
-                reentrant_msg = self._reentrant_messages.popleft()
-            except IndexError:
-                break
+        for reentrant_msg in iter(self._reentrant_messages.popleft,
+                                  stop_exception=IndexError):
             self._write(reentrant_msg)
         if msg is not None:
             self._write(msg)

Lib/xml/etree/ElementTree.py

@@ -1336,9 +1336,8 @@ def read_events(self):
         Events are consumed from the internal event queue as they are
         retrieved from the iterator.
         """
-        events = self._events_queue
-        while events:
-            event = events.popleft()
+        for event in iter(self._events_queue.popleft,
+                          stop_exception=IndexError):
             if isinstance(event, Exception):
                 raise event
             else: