From: Ruiyang Ke <me@ry.ke>
Date: Mon, 2 Feb 2026 10:04:18 +0000 (-0800)
Subject: gh-144380: Fix incorrect type check in `buffered_iternext()` (#144381)
X-Git-Tag: v3.15.0a6~104
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=40d07cad38bf3ce60f4ca03f1836e8650fe40df5;p=thirdparty%2FPython%2Fcpython.git

gh-144380: Fix incorrect type check in `buffered_iternext()` (#144381)
---

diff --git a/Misc/NEWS.d/next/Library/2026-02-01-15-25-00.gh-issue-144380.U7py_s.rst b/Misc/NEWS.d/next/Library/2026-02-01-15-25-00.gh-issue-144380.U7py_s.rst
new file mode 100644
index 000000000000..4b5b1b3776d7
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-02-01-15-25-00.gh-issue-144380.U7py_s.rst
@@ -0,0 +1 @@
+Improve performance of :class:`io.BufferedReader` line iteration by ~49%.
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 6d779abd89ca..0fdae7b2d210 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -1505,8 +1505,8 @@ buffered_iternext(PyObject *op)
 
     _PyIO_State *state = find_io_state_by_def(Py_TYPE(self));
     tp = Py_TYPE(self);
-    if (Py_IS_TYPE(tp, state->PyBufferedReader_Type) ||
-        Py_IS_TYPE(tp, state->PyBufferedRandom_Type))
+    if (tp == state->PyBufferedReader_Type ||
+        tp == state->PyBufferedRandom_Type)
     {
         /* Skip method call overhead for speed */
         line = _buffered_readline(self, -1);