gh-120144: Disable the CALL event when possible to achieve zero overhead pdb (#131390)

gaogaotiantian · web-flow · commit e3564689a598 · 2025-03-20T20:31:55.000-04:00
diff --git a/Lib/bdb.py b/Lib/bdb.py
@@ -342,7 +342,12 @@ def dispatch_call(self, frame, arg):
             self.botframe = frame.f_back # (CT) Note that this may also be None!
             return self.trace_dispatch
         if not (self.stop_here(frame) or self.break_anywhere(frame)):
-            # No need to trace this function
+            # We already know there's no breakpoint in this function
+            # If it's a next/until/return command, we don't need any CALL event
+            # and we don't need to set the f_trace on any new frame.
+            # If it's a step command, it must either hit stop_here, or skip the
+            # whole module. Either way, we don't need the CALL event here.
+            self.disable_current_event()
             return # None
         # Ignore call events in generator except when stepping.
         if self.stopframe and frame.f_code.co_flags & GENERATOR_AND_COROUTINE_FLAGS:
diff --git a/Misc/NEWS.d/next/Library/2025-03-18-02-11-33.gh-issue-120144.dBLFkI.rst b/Misc/NEWS.d/next/Library/2025-03-18-02-11-33.gh-issue-120144.dBLFkI.rst
@@ -0,0 +1 @@
+Disable ``CALL`` event in :mod:`bdb` in ``monitoring`` backend when we don't need any new events on the code object to get a better performance.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Disable ``CALL`` event in :mod:`bdb` in ``monitoring`` backend when we don't need any new events on the code object to get a better performance.