https://github.com/python/cpython/commit/d3015873693eaa30f904deada5e46374a1d31f6e
commit: d3015873693eaa30f904deada5e46374a1d31f6e
branch: main
author: Maurycy Pawłowski-Wieroński <[email protected]>
committer: vstinner <[email protected]>
date: 2025-10-15T14:04:17Z
summary:
gh-140135: Use `PyBytesWriter` in `io.RawIOBase.readall()`; 4x faster (#140139)
files:
A Misc/NEWS.d/next/Library/2025-10-15-02-26-50.gh-issue-140135.54JYfM.rst
M Modules/_io/iobase.c
diff --git
a/Misc/NEWS.d/next/Library/2025-10-15-02-26-50.gh-issue-140135.54JYfM.rst
b/Misc/NEWS.d/next/Library/2025-10-15-02-26-50.gh-issue-140135.54JYfM.rst
new file mode 100644
index 00000000000000..8d5a76af90906a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-10-15-02-26-50.gh-issue-140135.54JYfM.rst
@@ -0,0 +1,2 @@
+Speed up :meth:`io.RawIOBase.readall` by using PyBytesWriter API (about 4x
+faster)
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index aa373f6fdcb9d9..acadbcc4d59c38 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -962,12 +962,10 @@ static PyObject *
_io__RawIOBase_readall_impl(PyObject *self)
/*[clinic end generated code: output=1987b9ce929425a0 input=688874141213622a]*/
{
- int r;
- PyObject *chunks = PyList_New(0);
- PyObject *result;
-
- if (chunks == NULL)
+ PyBytesWriter *writer = PyBytesWriter_Create(0);
+ if (writer == NULL) {
return NULL;
+ }
while (1) {
PyObject *data = _PyObject_CallMethod(self, &_Py_ID(read),
@@ -978,21 +976,21 @@ _io__RawIOBase_readall_impl(PyObject *self)
if (_PyIO_trap_eintr()) {
continue;
}
- Py_DECREF(chunks);
+ PyBytesWriter_Discard(writer);
return NULL;
}
if (data == Py_None) {
- if (PyList_GET_SIZE(chunks) == 0) {
- Py_DECREF(chunks);
+ if (PyBytesWriter_GetSize(writer) == 0) {
+ PyBytesWriter_Discard(writer);
return data;
}
Py_DECREF(data);
break;
}
if (!PyBytes_Check(data)) {
- Py_DECREF(chunks);
Py_DECREF(data);
PyErr_SetString(PyExc_TypeError, "read() should return bytes");
+ PyBytesWriter_Discard(writer);
return NULL;
}
if (PyBytes_GET_SIZE(data) == 0) {
@@ -1000,16 +998,16 @@ _io__RawIOBase_readall_impl(PyObject *self)
Py_DECREF(data);
break;
}
- r = PyList_Append(chunks, data);
- Py_DECREF(data);
- if (r < 0) {
- Py_DECREF(chunks);
+ if (PyBytesWriter_WriteBytes(writer,
+ PyBytes_AS_STRING(data),
+ PyBytes_GET_SIZE(data)) < 0) {
+ Py_DECREF(data);
+ PyBytesWriter_Discard(writer);
return NULL;
}
+ Py_DECREF(data);
}
- result = PyBytes_Join((PyObject *)&_Py_SINGLETON(bytes_empty), chunks);
- Py_DECREF(chunks);
- return result;
+ return PyBytesWriter_Finish(writer);
}
static PyObject *
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