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Diffstat (limited to 'Doc/howto/isolating-extensions.rst')
| -rw-r--r-- | Doc/howto/isolating-extensions.rst | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/Doc/howto/isolating-extensions.rst b/Doc/howto/isolating-extensions.rst index a636e06bda8..5513cd73675 100644 --- a/Doc/howto/isolating-extensions.rst +++ b/Doc/howto/isolating-extensions.rst @@ -215,21 +215,36 @@ multiple interpreters correctly. If this is not yet the case for your module, you can explicitly make your module loadable only once per process. For example:: + // A process-wide flag static int loaded = 0; + // Mutex to provide thread safety (only needed for free-threaded Python) + static PyMutex modinit_mutex = {0}; + static int exec_module(PyObject* module) { + PyMutex_Lock(&modinit_mutex); if (loaded) { + PyMutex_Unlock(&modinit_mutex); PyErr_SetString(PyExc_ImportError, "cannot load module more than once per process"); return -1; } loaded = 1; + PyMutex_Unlock(&modinit_mutex); // ... rest of initialization } +If your module's :c:member:`PyModuleDef.m_clear` function is able to prepare +for future re-initialization, it should clear the ``loaded`` flag. +In this case, your module won't support multiple instances existing +*concurrently*, but it will, for example, support being loaded after +Python runtime shutdown (:c:func:`Py_FinalizeEx`) and re-initialization +(:c:func:`Py_Initialize`). + + Module State Access from Functions ---------------------------------- |