https://github.com/python/cpython/commit/1a9cdaf63af7014dd7bd852b4d8a8c0ab98387ab
commit: 1a9cdaf63af7014dd7bd852b4d8a8c0ab98387ab
branch: main
author: Alper <[email protected]>
committer: colesbury <[email protected]>
date: 2025-12-15T12:47:04-05:00
summary:
gh-116738: Make _bz2 module thread-safe (gh-142756)
Make the attributes in _bz2 module thread-safe on the free-threading build.
Attributes (eof, needs_input, unused_data) are now stored atomically or
accessed via mutex-protected getters.
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-12-15-03-20-24.gh-issue-116738.NNHiTK.rst
M Lib/test/test_free_threading/test_bz2.py
M Modules/_bz2module.c
diff --git a/Lib/test/test_free_threading/test_bz2.py
b/Lib/test/test_free_threading/test_bz2.py
index 0e09c64d5610a3..3bb531ec04c6c9 100644
--- a/Lib/test/test_free_threading/test_bz2.py
+++ b/Lib/test/test_free_threading/test_bz2.py
@@ -42,11 +42,22 @@ def worker():
data = bz2d.decompress(compressed, chunk_size)
self.assertEqual(len(data), chunk_size)
output.append(data)
+ # Read attributes concurrently with other threads decompressing
+ self.assertIsInstance(bz2d.eof, bool)
+ self.assertIsInstance(bz2d.needs_input, bool)
+ self.assertIsInstance(bz2d.unused_data, bytes)
run_concurrently(worker_func=worker, nthreads=NTHREADS)
self.assertEqual(len(output), NTHREADS)
# Verify the expected chunks (order doesn't matter due to append race)
self.assertEqual(set(output), set(chunks))
+ self.assertTrue(bz2d.eof)
+ self.assertFalse(bz2d.needs_input)
+ # Each thread added full compressed data to the buffer, but only 1 copy
+ # is consumed to produce the output. The rest remains as unused_data.
+ self.assertEqual(
+ len(bz2d.unused_data), len(compressed) * (NTHREADS - 1)
+ )
if __name__ == "__main__":
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-12-15-03-20-24.gh-issue-116738.NNHiTK.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-15-03-20-24.gh-issue-116738.NNHiTK.rst
new file mode 100644
index 00000000000000..bf06dfee23291e
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-12-15-03-20-24.gh-issue-116738.NNHiTK.rst
@@ -0,0 +1,2 @@
+Make the attributes in :mod:`bz2` thread-safe on the :term:`free threaded
+<free threading>` build.
diff --git a/Modules/_bz2module.c b/Modules/_bz2module.c
index 452b88dfed29ce..f3457a13c96c1f 100644
--- a/Modules/_bz2module.c
+++ b/Modules/_bz2module.c
@@ -12,6 +12,7 @@
// Blocks output buffer wrappers
#include "pycore_blocks_output_buffer.h"
+#include "pycore_pyatomic_ft_wrappers.h" // FT_ATOMIC_STORE_CHAR_RELAXED
#if OUTPUT_BUFFER_MAX_BLOCK_SIZE > UINT32_MAX
#error "The maximum block size accepted by libbzip2 is UINT32_MAX."
@@ -437,7 +438,7 @@ decompress_buf(BZ2Decompressor *d, Py_ssize_t max_length)
if (catch_bz2_error(bzret))
goto error;
if (bzret == BZ_STREAM_END) {
- d->eof = 1;
+ FT_ATOMIC_STORE_CHAR_RELAXED(d->eof, 1);
break;
} else if (d->bzs_avail_in_real == 0) {
break;
@@ -521,7 +522,7 @@ decompress(BZ2Decompressor *d, char *data, size_t len,
Py_ssize_t max_length)
}
if (d->eof) {
- d->needs_input = 0;
+ FT_ATOMIC_STORE_CHAR_RELAXED(d->needs_input, 0);
if (d->bzs_avail_in_real > 0) {
Py_XSETREF(d->unused_data,
PyBytes_FromStringAndSize(bzs->next_in,
d->bzs_avail_in_real));
@@ -531,10 +532,10 @@ decompress(BZ2Decompressor *d, char *data, size_t len,
Py_ssize_t max_length)
}
else if (d->bzs_avail_in_real == 0) {
bzs->next_in = NULL;
- d->needs_input = 1;
+ FT_ATOMIC_STORE_CHAR_RELAXED(d->needs_input, 1);
}
else {
- d->needs_input = 0;
+ FT_ATOMIC_STORE_CHAR_RELAXED(d->needs_input, 0);
/* If we did not use the input buffer, we now have
to copy the tail from the caller's buffer into the
@@ -682,11 +683,28 @@ PyDoc_STRVAR(BZ2Decompressor_unused_data__doc__,
PyDoc_STRVAR(BZ2Decompressor_needs_input_doc,
"True if more input is needed before more decompressed data can be produced.");
+static PyObject *
+BZ2Decompressor_unused_data_get(PyObject *op, void *Py_UNUSED(ignored))
+{
+ BZ2Decompressor *self = _BZ2Decompressor_CAST(op);
+ PyMutex_Lock(&self->mutex);
+ PyObject *result = Py_XNewRef(self->unused_data);
+ PyMutex_Unlock(&self->mutex);
+ if (result == NULL) {
+ PyErr_SetString(PyExc_AttributeError, "unused_data");
+ }
+ return result;
+}
+
+static PyGetSetDef BZ2Decompressor_getset[] = {
+ {"unused_data", BZ2Decompressor_unused_data_get, NULL,
+ BZ2Decompressor_unused_data__doc__},
+ {NULL},
+};
+
static PyMemberDef BZ2Decompressor_members[] = {
{"eof", Py_T_BOOL, offsetof(BZ2Decompressor, eof),
Py_READONLY, BZ2Decompressor_eof__doc__},
- {"unused_data", Py_T_OBJECT_EX, offsetof(BZ2Decompressor, unused_data),
- Py_READONLY, BZ2Decompressor_unused_data__doc__},
{"needs_input", Py_T_BOOL, offsetof(BZ2Decompressor, needs_input),
Py_READONLY,
BZ2Decompressor_needs_input_doc},
{NULL}
@@ -697,6 +715,7 @@ static PyType_Slot bz2_decompressor_type_slots[] = {
{Py_tp_methods, BZ2Decompressor_methods},
{Py_tp_doc, (char *)_bz2_BZ2Decompressor__doc__},
{Py_tp_members, BZ2Decompressor_members},
+ {Py_tp_getset, BZ2Decompressor_getset},
{Py_tp_new, _bz2_BZ2Decompressor},
{0, 0}
};
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