Dave Malcolm <[email protected]> added the comment:
Attached is a new approach to doing this, based on "Out-Of-Memory Testing"
within http://sqlite.org/testing.html
This reads environment variables, and injects a fault at the given value of
"serialno", and (optionally) ongoing failures afterwards.
I used this to find a specific bug in Python/pythonrun.c (fix is the first hunk
of the patch): if moduleName is NULL, then Py_DECREF will read through NULL.
Potentially this gives the low-level machinery to support adding SQLite's
approach to be added to regrtest. Doing so would imply running each test many
tens of thousands of times, so perhaps we could run "-c pass" to establish at
what serialno the interpreter has fully started up, then use that as a starting
point when testing other scripts/modules.
I implemented a toy version of this as Lib/test/test_malloc_fault.py, which
sits in an infinite loop injecting individual allocation failures when starting
up sys.executable as a subprocess.
For low numbers, this throws up segfaults within _Py_ReadyTypes' call to
PyType_Ready(&PyType_Type), where PyExc_MemoryError is set but has not yet been
initialized (its ob_type is NULL):
/* this will probably fail since there's no memory and hee,
hee, we have to instantiate this class
*/
Running this interactively with a large value for PYTHONMALLOCINJECTFAULTSAT
leads to an interesting failure mode within PyRun_InteractiveLoopFlags(): every
call to PyRun_InteractiveOneFlags immediately returns (the
PyUnicode_FromString("stdin") in within PySys_GetObject() fails to allocate
memory); this leads to a tight loop sending the total refcount to stderr:
[52812 refs]
[52812 refs]
[52812 refs]
(etc)
----------
Added file: http://bugs.python.org/file19372/py3k-inject-malloc-failure-002.txt
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