[Python-Dev] bytearray and array.array are not thread-safe (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Sun Jul 6 00:28:43 CEST 2008

Short story: bytearray and array.array by construction allow user code to reallocate their internal memory buffer. But a raw pointer to the said buffer can also be obtained by another thread, and used after releasing the GIL (for CPU-intensive operations like compression). As a consequence, the interpreter crashes.

Was it envisioned?

I guess this wasn't considered. For t#, there is a comment from Travis that it really shouldn't release the buffer yet, but it does, anyway.

I propose that new codes s*, t*, w* are added, and that s#,t#,w# refuses objects which implement a releasebuffer procedure (alternatively, s# etc might be removed altogether right away). Users of s* then need to pass in a Py_Buffer view pointer that gets filled, and need to explicitly release the buffer. For convenience, it might help if the Py_buffer structure includes a borrowed PyObject* to the underlying object, along with a PyBuffer_Release procedure/macro.

Regards, Martin

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