Formats such as ``y*`` and ``s*`` fill a :c:type:`Py_buffer` structure. This locks the underlying buffer so that the caller can subsequently use the buffer even inside a :c:type:`Py_BEGIN_ALLOW_THREADS` block without the risk of mutable data being resized or destroyed. As a result, **you have to call** :c:func:`PyBuffer_Release` after you have finished processing the data (or in any early abort case).