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Try to repair at least one segfault on the Mac buildbot,

Browse source 
as diagnosed by Nick Coghlan.

test_capi.py:  A test module should never spawn a thread as
a side effect of being imported.  Because this one did, the
segfault one of its thread tests caused didn't occur until
a few tests after test_regrtest.py thought test_capi was
finished.  Repair that.  Also join() the thread spawned
at the end, so that test_capi is truly finished when
regrtest reports that it's done.

_testcapimodule.c test_thread_state():  this spawns a
couple of non-threading.py threads, passing them a PyObject*
argument, but did nothing to ensure that those threads
finished before returning.  As a result, the PyObject*
_could_ (although this was unlikely) get decref'ed out of
existence before the threads got around to using it.
Added explicit synchronization (via a Python mutex) so
that test_thread_state can reliably wait for its spawned
threads to finish.
This commit is contained in:
Tim Peters 2006-03-21 03:58:41 +00:00
parent 66760f87b5
commit 59b96c1029
2 changed files with 83 additions and 46 deletions
Download patch file Download diff file Expand all files Collapse all files

54
Modules/_testcapimodule.c
View file

@ -10,7 +10,6 @@
#ifdef WITH_THREAD
#include "pythread.h"
#endif /* WITH_THREAD */
static PyObject *TestError; /* set to exception object in init */
/* Raise TestError with test_name + ": " + msg, and return NULL. */
@ -482,7 +481,7 @@ static
PyObject *codec_incrementalencoder(PyObject *self, PyObject *args)
{
const char *encoding, *errors = NULL;
if (!PyArg_ParseTuple(args, "s|s:test_incrementalencoder",
if (!PyArg_ParseTuple(args, "s|s:test_incrementalencoder",
&encoding, &errors))
return NULL;
return PyCodec_IncrementalEncoder(encoding, errors);
@ -492,7 +491,7 @@ static
PyObject *codec_incrementaldecoder(PyObject *self, PyObject *args)
{
const char *encoding, *errors = NULL;
if (!PyArg_ParseTuple(args, "s|s:test_incrementaldecoder",
if (!PyArg_ParseTuple(args, "s|s:test_incrementaldecoder",
&encoding, &errors))
return NULL;
return PyCodec_IncrementalDecoder(encoding, errors);
@ -583,7 +582,17 @@ raise_exception(PyObject *self, PyObject *args)
#ifdef WITH_THREAD
void _make_call(void *callable)
/* test_thread_state spawns a thread of its own, and that thread releases
* `thread_done` when it's finished. The driver code has to know when the
* thread finishes, because the thread uses a PyObject (the callable) that
* may go away when the driver finishes. The former lack of this explicit
* synchronization caused rare segfaults, so rare that they were seen only
* on a Mac buildbot (although they were possible on any box).
*/
static PyThread_type_lock thread_done = NULL;
static void
_make_call(void *callable)
{
PyObject *rc;
PyGILState_STATE s = PyGILState_Ensure();
@ -592,32 +601,53 @@ void _make_call(void *callable)
PyGILState_Release(s);
}
/* Same thing, but releases `thread_done` when it returns. This variant
* should be called only from threads spawned by test_thread_state().
*/
static void
_make_call_from_thread(void *callable)
{
_make_call(callable);
PyThread_release_lock(thread_done);
}
static PyObject *
test_thread_state(PyObject *self, PyObject *args)
{
PyObject *fn;
if (!PyArg_ParseTuple(args, "O:test_thread_state", &fn))
return NULL;
/* Ensure Python is setup for threading */
/* Ensure Python is set up for threading */
PyEval_InitThreads();
/* Start a new thread for our callback. */
PyThread_start_new_thread( _make_call, fn);
thread_done = PyThread_allocate_lock();
if (thread_done == NULL)
return PyErr_NoMemory();
PyThread_acquire_lock(thread_done, 1);
/* Start a new thread with our callback. */
PyThread_start_new_thread(_make_call_from_thread, fn);
/* Make the callback with the thread lock held by this thread */
_make_call(fn);
/* Do it all again, but this time with the thread-lock released */
Py_BEGIN_ALLOW_THREADS
_make_call(fn);
PyThread_acquire_lock(thread_done, 1); /* wait for thread to finish */
Py_END_ALLOW_THREADS
/* And once more with and without a thread
XXX - should use a lock and work out exactly what we are trying
to test <wink>
XXX - should use a lock and work out exactly what we are trying
to test <wink>
*/
Py_BEGIN_ALLOW_THREADS
PyThread_start_new_thread( _make_call, fn);
PyThread_start_new_thread(_make_call_from_thread, fn);
_make_call(fn);
PyThread_acquire_lock(thread_done, 1); /* wait for thread to finish */
Py_END_ALLOW_THREADS
Py_INCREF(Py_None);
return Py_None;
PyThread_free_lock(thread_done);
Py_RETURN_NONE;
}
#endif