https://github.com/python/cpython/commit/5466f57eaddeec7f07a681993b22167e42c9807a
commit: 5466f57eaddeec7f07a681993b22167e42c9807a
branch: main
author: Kumar Aditya <[email protected]>
committer: kumaraditya303 <[email protected]>
date: 2026-03-27T18:40:26+05:30
summary:
gh-142518: add thread safety annotations for bytearray C-API (#146514)
files:
M Doc/c-api/bytearray.rst
M Doc/data/threadsafety.dat
diff --git a/Doc/c-api/bytearray.rst b/Doc/c-api/bytearray.rst
index e2b22ec3c794ae..2b36da997d4295 100644
--- a/Doc/c-api/bytearray.rst
+++ b/Doc/c-api/bytearray.rst
@@ -44,6 +44,10 @@ Direct API functions
On failure, return ``NULL`` with an exception set.
+ .. note::
+ If the object implements the buffer protocol, then the buffer
+ must not be mutated while the bytearray object is being created.
+
.. c:function:: PyObject* PyByteArray_FromStringAndSize(const char *string,
Py_ssize_t len)
@@ -58,6 +62,10 @@ Direct API functions
On failure, return ``NULL`` with an exception set.
+ .. note::
+ If the object implements the buffer protocol, then the buffer
+ must not be mutated while the bytearray object is being created.
+
.. c:function:: Py_ssize_t PyByteArray_Size(PyObject *bytearray)
@@ -70,6 +78,9 @@ Direct API functions
``NULL`` pointer. The returned array always has an extra
null byte appended.
+ .. note::
+ It is not thread-safe to mutate the bytearray object while using the
returned char array.
+
.. c:function:: int PyByteArray_Resize(PyObject *bytearray, Py_ssize_t len)
@@ -89,6 +100,9 @@ These macros trade safety for speed and they don't check
pointers.
Similar to :c:func:`PyByteArray_AsString`, but without error checking.
+ .. note::
+ It is not thread-safe to mutate the bytearray object while using the
returned char array.
+
.. c:function:: Py_ssize_t PyByteArray_GET_SIZE(PyObject *bytearray)
diff --git a/Doc/data/threadsafety.dat b/Doc/data/threadsafety.dat
index 1210ab17aaa35b..afb053adf5c62b 100644
--- a/Doc/data/threadsafety.dat
+++ b/Doc/data/threadsafety.dat
@@ -107,3 +107,20 @@ _PyBytes_Resize:distinct:
# Repr - atomic as bytes are immutable
PyBytes_Repr:atomic:
+
+# Creation from object - may call arbitrary code
+PyByteArray_FromObject:shared:
+
+# Creation - pure allocation, no shared state
+PyByteArray_FromStringAndSize:atomic:
+
+# Concatenation - uses buffer protocol; safe as long as buffer is not mutated
by another thread during the operation
+PyByteArray_Concat:shared:
+
+# Size - uses atomic load on free-threaded builds
+PyByteArray_Size:atomic:
+PyByteArray_GET_SIZE:atomic:
+
+# Raw data - no locking; mutating it is unsafe if the bytearray object is
shared between threads
+PyByteArray_AsString:compatible:
+PyByteArray_AS_STRING:compatible:
\ No newline at end of file
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