| Boyan Boyadjiev (JIRA) 2005-11-04, 7:45 am |
| [ http://issues.apache.org/jira/brows...action_12356757 ]
Boyan Boyadjiev commented on MODPYTHON-77:
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Sorry - I didn't saw the change done for MODPYTHON-83. PyThreadState_Swap must be added in the non thread case of release_interpreter.
With "smallest required change" I just wanted to say, that if the GIL stuff is not going to be used in mod_python, there is still somehing to do in order to handle the Python thread state in a proper way since Python 2.3.5.
I think, that the most proper fix will be mod_python.?.diff + PyThreadState_Swap.
Now a different point regarding internal_redirect. What will hapen if interpreter1 call internal_redirect into interpreter2? Could it be, that the block
Py_BEGIN_ALLOW_THREADS
ap_internal_redirect(new_uri, self->request_rec);
Py_END_ALLOW_THREADS
is not sofficient any more and should be changed in something like this
release_interpreter
ap_internal_redirect(new_uri, self->request_rec);
get_interpreter
> The multiple interpreter concept of mod_python is broken for Python extension modules since Python 2.3
> ------------------------------------------------------------------------------------------------------
>
> Key: MODPYTHON-77
> URL: http://issues.apache.org/jira/browse/MODPYTHON-77
> Project: mod_python
> Type: Bug
> Components: core
> Versions: 3.1.4
> Environment: Python >= 2.3
> Reporter: Boyan Boyadjiev
> Attachments: diff.txt, diff2.txt, diff3.txt, gil_test.c, gilstate.tar.gz, mod_python.c, mod_python.c.diff, mod_python.h.diff, src.zip
>
> The multiple interpreter concept of mod_python is broken for Python extension modules since Python 2.3 because of the PEP 311 (Simplified Global Interpreter Lock Acquisition for Extensions):
> ...
> Limitations and Exclusions
> This proposal identifies a solution for extension authors with
> complex multi-threaded requirements, but that only require a
> single "PyInterpreterState". There is no attempt to cater for
> extensions that require multiple interpreter states. At the time
> of writing, no extension has been identified that requires
> multiple PyInterpreterStates, and indeed it is not clear if that
> facility works correctly in Python itself.
> ...
> For mod_python this means, that complex Python extensions won't work any more with Python >= 2.3, because they are supposed to work only with the first interpreter state initialized for the current process (a problem we experienced). The first interpret
er state is not used by mod_python after the python_init is called.
> One solution, which works fine for me, is to save the first interpreter state into the "interpreters" dictionary in the function python_init (MAIN_INTERPRETER is used as a key):
> static int python_init(apr_pool_t *p, apr_pool_t *ptemp,
> apr_pool_t *plog, server_rec *s)
> {
> ...
> /* initialize global Python interpreter if necessary */
> if (! Py_IsInitialized())
> {
> /* initialze the interpreter */
> Py_Initialize();
> #ifdef WITH_THREAD
> /* create and acquire the interpreter lock */
> PyEval_InitThreads();
> #endif
> /* create the obCallBack dictionary */
> interpreters = PyDict_New();
> if (! interpreters) {
> ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, s,
> "python_init: PyDict_New() failed! No more memory?");
> exit(1);
> }
> {
> /*
> Workaround PEP 311 - Simplified Global Interpreter Lock Acquisition for Extensions
> BEGIN
> */
> PyObject *p = 0;
> interpreterdata * idata = (interpreterdata *)malloc(sizeof(interpreterdata));
> PyThreadState* currentThreadState = PyThreadState_Get();
> PyInterpreterState *istate = currentThreadState->interp;
> idata->istate = istate;
> /* obcallback will be created on first use */
> idata->obcallback = NULL;
> p = PyCObject_FromVoidPtr((void ) idata, NULL); /*p->refcout = 1*/
> PyDict_SetItemString(interpreters, MAIN_INTERPRETER, p); /*p->refcout = 2*/
> Py_DECREF(p); /*p->refcout = 1*/
> /*
> END
> Workaround PEP 311 - Simplified Global Interpreter Lock Acquisition for Extensions
> */
> }
> /* Release the thread state because we will never use
> * the main interpreter, only sub interpreters created later. */
> PyThreadState_Swap(NULL);
> #ifdef WITH_THREAD
> /* release the lock; now other threads can run */
> PyEval_ReleaseLock();
> #endif
> }
> return OK;
> }
> Another change I've made in the attached file is to Py_DECREF(p) in get_interpreter, which will remove leaky reference to the PyCObject with the interpreter data. This was not a real problem, but now I see fewer leaks in BoundsChecker :-).
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