gh-91555: disable logger while handling log record (GH-131812)

Prevent the possibility of re-entrancy leading to deadlock or infinite recursion (caused by logging triggered by logging), by disabling logging while the logger is handling log messages.

Lib/logging/__init__.py

@@ -1474,6 +1474,8 @@ class Logger(Filterer):
     level, and "input.csv", "input.xls" and "input.gnu" for the sub-levels.
     There is no arbitrary limit to the depth of nesting.
     """
+    _tls = threading.local()
+
     def __init__(self, name, level=NOTSET):
         """
         Initialize the logger with a name and an optional level.
@@ -1670,14 +1672,19 @@ class Logger(Filterer):
         This method is used for unpickled records received from a socket, as
         well as those created locally. Logger-level filtering is applied.
         """
-        if self.disabled:
+        if self._is_disabled():
             return
-        maybe_record = self.filter(record)
-        if not maybe_record:
-            return
-        if isinstance(maybe_record, LogRecord):
-            record = maybe_record
-        self.callHandlers(record)
+
+        self._tls.in_progress = True
+        try:
+            maybe_record = self.filter(record)
+            if not maybe_record:
+                return
+            if isinstance(maybe_record, LogRecord):
+                record = maybe_record
+            self.callHandlers(record)
+        finally:
+            self._tls.in_progress = False
 
     def addHandler(self, hdlr):
         """
@@ -1765,7 +1772,7 @@ class Logger(Filterer):
         """
         Is this logger enabled for level 'level'?
         """
-        if self.disabled:
+        if self._is_disabled():
             return False
 
         try:
@@ -1815,6 +1822,11 @@ class Logger(Filterer):
                        if isinstance(item, Logger) and item.parent is self and
                        _hierlevel(item) == 1 + _hierlevel(item.parent))
 
+    def _is_disabled(self):
+        # We need to use getattr as it will only be set the first time a log
+        # message is recorded on any given thread
+        return self.disabled or getattr(self._tls, 'in_progress', False)
+
     def __repr__(self):
         level = getLevelName(self.getEffectiveLevel())
         return '<%s %s (%s)>' % (self.__class__.__name__, self.name, level)