Do not import rlcompleter in complete* methods

Author: gaogaotiantian

Lib/pdb.py

@@ -363,6 +363,15 @@ def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None,
             readline.set_completer_delims(' \t\n`@#%^&*()=+[{]}\\|;:\'",<>?')
         except ImportError:
             pass
+
+        # GH-138860
+        # We need to lazy-import rlcompleter to avoid deadlock
+        # We cannot import it during self.complete* methods because importing
+        # rlcompleter for the first time will overwrite readline's completer
+        # So we import it here and save the Completer class
+        from rlcompleter import Completer
+        self.RlCompleter = Completer
+
         self.allow_kbdint = False
         self.nosigint = nosigint
         # Consider these characters as part of the command so when the users type
@@ -1185,13 +1194,9 @@ def completedefault(self, text, line, begidx, endidx):
             conv_vars = self.curframe.f_globals.get('__pdb_convenience_variables', {})
             return [f"${name}" for name in conv_vars if name.startswith(text[1:])]
 
-        # Use rlcompleter to do the completion
-        # GH-138860
-        # This needs to be lazy-imported to avoid deadlock
-        from rlcompleter import Completer
         state = 0
         matches = []
-        completer = Completer(self.curframe.f_globals | self.curframe.f_locals)
+        completer = self.RlCompleter(self.curframe.f_globals | self.curframe.f_locals)
         while (match := completer.complete(text, state)) is not None:
             matches.append(match)
             state += 1
@@ -1206,11 +1211,8 @@ def _enable_rlcompleter(self, ns):
             return
 
         try:
+            completer = self.RlCompleter(ns)
             old_completer = readline.get_completer()
-            # GH-138860
-            # This needs to be lazy-imported to avoid deadlock
-            from rlcompleter import Completer
-            completer = Completer(ns)
             readline.set_completer(completer.complete)
             yield
         finally:
@@ -3155,6 +3157,7 @@ def read_command(self, prompt):
     def readline_completion(self, completer):
         try:
             import readline
+            import rlcompleter
         except ImportError:
             yield
             return