Experimental support for free-threaded Python.

Author: droe

NEWS.md

@@ -1,5 +1,6 @@
 ### acefile 0.6.14-dev
 
+-   Experimental support for free-threaded Python.
 -   Fix memory leak in acebitstream module.
 -   Add pytest smoke tests and configure GitHub Actions CI for testing.
 -   Remove deprecated setup.py features.

apidoc/index.rst

@@ -22,6 +22,9 @@ Typical use of :mod:`acefile` has the following structure:
 See :class:`acefile.AceArchive` and :class:`acefile.AceMember` for the
 complete descriptions of the methods supported by these two classes.
 
+On free-threaded Python, :mod:`acefile` is only thread-safe as long as only a
+single thread operates on any given :class:`acefile.AceArchive` at a time.
+
 Functions
 ~~~~~~~~~
 

c/acebitstream_mod.c

@@ -290,6 +290,17 @@ PyInit_acebitstream(void)
 		return NULL;
 	}
 
+#ifdef Py_GIL_DISABLED
+	/*
+	 * There are no critical sections, because the premise is that
+	 * decompression from the same file-like object is inherently not
+	 * thread-safe.  Decompressing archive members from the same non-solid
+	 * archive in parallel would need to be made thread-safe at a higher
+	 * layer than reading bits from a file-like object.
+	 */
+	PyUnstable_Module_SetGIL(module, Py_MOD_GIL_NOT_USED);
+#endif
+
 	Py_INCREF(&BitStreamType);
 	PyModule_AddObject(module, "BitStream", (PyObject*)&BitStreamType);
 	return module;