diff options
| -rw-r--r-- | Include/cpython/pystate.h | 3 | ||||
| -rw-r--r-- | Include/internal/pycore_ceval.h | 16 | ||||
| -rw-r--r-- | Lib/test/test_exceptions.py | 52 | ||||
| -rw-r--r-- | Lib/test/test_sys.py | 46 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Core and Builtins/2020-11-30-14-27-29.bpo-42500.excVKU.rst | 2 | ||||
| -rw-r--r-- | Python/ceval.c | 20 | ||||
| -rw-r--r-- | Python/errors.c | 3 | ||||
| -rw-r--r-- | Python/pystate.c | 2 | ||||
| -rw-r--r-- | Python/sysmodule.c | 4 |
9 files changed, 76 insertions, 72 deletions
diff --git a/Include/cpython/pystate.h b/Include/cpython/pystate.h index 0e6cc29..cfaee89 100644 --- a/Include/cpython/pystate.h +++ b/Include/cpython/pystate.h @@ -54,8 +54,7 @@ struct _ts { /* Borrowed reference to the current frame (it can be NULL) */ PyFrameObject *frame; int recursion_depth; - char overflowed; /* The stack has overflowed. Allow 50 more calls - to handle the runtime error. */ + int recursion_headroom; /* Allow 50 more calls to handle any errors. */ int stackcheck_counter; /* 'tracing' keeps track of the execution depth when tracing/profiling. diff --git a/Include/internal/pycore_ceval.h b/Include/internal/pycore_ceval.h index bbb667e..38fd681 100644 --- a/Include/internal/pycore_ceval.h +++ b/Include/internal/pycore_ceval.h @@ -92,24 +92,8 @@ static inline int _Py_EnterRecursiveCall_inline(const char *where) { #define Py_EnterRecursiveCall(where) _Py_EnterRecursiveCall_inline(where) -/* Compute the "lower-water mark" for a recursion limit. When - * Py_LeaveRecursiveCall() is called with a recursion depth below this mark, - * the overflowed flag is reset to 0. */ -static inline int _Py_RecursionLimitLowerWaterMark(int limit) { - if (limit > 200) { - return (limit - 50); - } - else { - return (3 * (limit >> 2)); - } -} - static inline void _Py_LeaveRecursiveCall(PyThreadState *tstate) { tstate->recursion_depth--; - int limit = tstate->interp->ceval.recursion_limit; - if (tstate->recursion_depth < _Py_RecursionLimitLowerWaterMark(limit)) { - tstate->overflowed = 0; - } } static inline void _Py_LeaveRecursiveCall_inline(void) { diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py index 4dbf5fe..1bdd3f2 100644 --- a/Lib/test/test_exceptions.py +++ b/Lib/test/test_exceptions.py @@ -1046,7 +1046,7 @@ class ExceptionTests(unittest.TestCase): # tstate->recursion_depth is equal to (recursion_limit - 1) # and is equal to recursion_limit when _gen_throw() calls # PyErr_NormalizeException(). - recurse(setrecursionlimit(depth + 2) - depth - 1) + recurse(setrecursionlimit(depth + 2) - depth) finally: sys.setrecursionlimit(recursionlimit) print('Done.') @@ -1076,6 +1076,54 @@ class ExceptionTests(unittest.TestCase): b'while normalizing an exception', err) self.assertIn(b'Done.', out) + + def test_recursion_in_except_handler(self): + + def set_relative_recursion_limit(n): + depth = 1 + while True: + try: + sys.setrecursionlimit(depth) + except RecursionError: + depth += 1 + else: + break + sys.setrecursionlimit(depth+n) + + def recurse_in_except(): + try: + 1/0 + except: + recurse_in_except() + + def recurse_after_except(): + try: + 1/0 + except: + pass + recurse_after_except() + + def recurse_in_body_and_except(): + try: + recurse_in_body_and_except() + except: + recurse_in_body_and_except() + + recursionlimit = sys.getrecursionlimit() + try: + set_relative_recursion_limit(10) + for func in (recurse_in_except, recurse_after_except, recurse_in_body_and_except): + with self.subTest(func=func): + try: + func() + except RecursionError: + pass + else: + self.fail("Should have raised a RecursionError") + finally: + sys.setrecursionlimit(recursionlimit) + + @cpython_only def test_recursion_normalizing_with_no_memory(self): # Issue #30697. Test that in the abort that occurs when there is no @@ -1112,7 +1160,7 @@ class ExceptionTests(unittest.TestCase): except MemoryError as e: tb = e.__traceback__ else: - self.fail("Should have raises a MemoryError") + self.fail("Should have raised a MemoryError") return traceback.format_tb(tb) tb1 = raiseMemError() diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py index 173ef9e..3860656 100644 --- a/Lib/test/test_sys.py +++ b/Lib/test/test_sys.py @@ -221,7 +221,7 @@ class SysModuleTest(unittest.TestCase): def f(): f() try: - for depth in (10, 25, 50, 75, 100, 250, 1000): + for depth in (50, 75, 100, 250, 1000): try: sys.setrecursionlimit(depth) except RecursionError: @@ -231,17 +231,17 @@ class SysModuleTest(unittest.TestCase): # Issue #5392: test stack overflow after hitting recursion # limit twice - self.assertRaises(RecursionError, f) - self.assertRaises(RecursionError, f) + with self.assertRaises(RecursionError): + f() + with self.assertRaises(RecursionError): + f() finally: sys.setrecursionlimit(oldlimit) @test.support.cpython_only def test_setrecursionlimit_recursion_depth(self): # Issue #25274: Setting a low recursion limit must be blocked if the - # current recursion depth is already higher than the "lower-water - # mark". Otherwise, it may not be possible anymore to - # reset the overflowed flag to 0. + # current recursion depth is already higher than limit. from _testinternalcapi import get_recursion_depth @@ -262,42 +262,10 @@ class SysModuleTest(unittest.TestCase): sys.setrecursionlimit(1000) for limit in (10, 25, 50, 75, 100, 150, 200): - # formula extracted from _Py_RecursionLimitLowerWaterMark() - if limit > 200: - depth = limit - 50 - else: - depth = limit * 3 // 4 - set_recursion_limit_at_depth(depth, limit) + set_recursion_limit_at_depth(limit, limit) finally: sys.setrecursionlimit(oldlimit) - # The error message is specific to CPython - @test.support.cpython_only - def test_recursionlimit_fatalerror(self): - # A fatal error occurs if a second recursion limit is hit when recovering - # from a first one. - code = textwrap.dedent(""" - import sys - - def f(): - try: - f() - except RecursionError: - f() - - sys.setrecursionlimit(%d) - f()""") - with test.support.SuppressCrashReport(): - for i in (50, 1000): - sub = subprocess.Popen([sys.executable, '-c', code % i], - stderr=subprocess.PIPE) - err = sub.communicate()[1] - self.assertTrue(sub.returncode, sub.returncode) - self.assertIn( - b"Fatal Python error: _Py_CheckRecursiveCall: " - b"Cannot recover from stack overflow", - err) - def test_getwindowsversion(self): # Raise SkipTest if sys doesn't have getwindowsversion attribute test.support.get_attribute(sys, "getwindowsversion") diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-11-30-14-27-29.bpo-42500.excVKU.rst b/Misc/NEWS.d/next/Core and Builtins/2020-11-30-14-27-29.bpo-42500.excVKU.rst new file mode 100644 index 0000000..2462a8e --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2020-11-30-14-27-29.bpo-42500.excVKU.rst @@ -0,0 +1,2 @@ +Improve handling of exceptions near recursion limit. Converts a number of +Fatal Errors in RecursionErrors. diff --git a/Python/ceval.c b/Python/ceval.c index 693852e..9de9257 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -857,20 +857,22 @@ _Py_CheckRecursiveCall(PyThreadState *tstate, const char *where) return -1; } #endif - if (tstate->overflowed) { + if (tstate->recursion_headroom) { if (tstate->recursion_depth > recursion_limit + 50) { /* Overflowing while handling an overflow. Give up. */ Py_FatalError("Cannot recover from stack overflow."); } - return 0; } - if (tstate->recursion_depth > recursion_limit) { - --tstate->recursion_depth; - tstate->overflowed = 1; - _PyErr_Format(tstate, PyExc_RecursionError, - "maximum recursion depth exceeded%s", - where); - return -1; + else { + if (tstate->recursion_depth > recursion_limit) { + tstate->recursion_headroom++; + _PyErr_Format(tstate, PyExc_RecursionError, + "maximum recursion depth exceeded%s", + where); + tstate->recursion_headroom--; + --tstate->recursion_depth; + return -1; + } } return 0; } diff --git a/Python/errors.c b/Python/errors.c index f80ae21..8242ac6 100644 --- a/Python/errors.c +++ b/Python/errors.c @@ -290,12 +290,14 @@ _PyErr_NormalizeException(PyThreadState *tstate, PyObject **exc, PyObject **val, PyObject **tb) { int recursion_depth = 0; + tstate->recursion_headroom++; PyObject *type, *value, *initial_tb; restart: type = *exc; if (type == NULL) { /* There was no exception, so nothing to do. */ + tstate->recursion_headroom--; return; } @@ -347,6 +349,7 @@ _PyErr_NormalizeException(PyThreadState *tstate, PyObject **exc, } *exc = type; *val = value; + tstate->recursion_headroom--; return; error: diff --git a/Python/pystate.c b/Python/pystate.c index 600cc5e..8da583f 100644 --- a/Python/pystate.c +++ b/Python/pystate.c @@ -605,7 +605,7 @@ new_threadstate(PyInterpreterState *interp, int init) tstate->frame = NULL; tstate->recursion_depth = 0; - tstate->overflowed = 0; + tstate->recursion_headroom = 0; tstate->stackcheck_counter = 0; tstate->tracing = 0; tstate->use_tracing = 0; diff --git a/Python/sysmodule.c b/Python/sysmodule.c index f05b33a..b80d37d 100644 --- a/Python/sysmodule.c +++ b/Python/sysmodule.c @@ -1181,7 +1181,6 @@ static PyObject * sys_setrecursionlimit_impl(PyObject *module, int new_limit) /*[clinic end generated code: output=35e1c64754800ace input=b0f7a23393924af3]*/ { - int mark; PyThreadState *tstate = _PyThreadState_GET(); if (new_limit < 1) { @@ -1199,8 +1198,7 @@ sys_setrecursionlimit_impl(PyObject *module, int new_limit) Reject too low new limit if the current recursion depth is higher than the new low-water mark. Otherwise it may not be possible anymore to reset the overflowed flag to 0. */ - mark = _Py_RecursionLimitLowerWaterMark(new_limit); - if (tstate->recursion_depth >= mark) { + if (tstate->recursion_depth >= new_limit) { _PyErr_Format(tstate, PyExc_RecursionError, "cannot set the recursion limit to %i at " "the recursion depth %i: the limit is too low", |