cpython: 2b4b289c1abb (original) (raw)

Mercurial > cpython

changeset 83772:2b4b289c1abb 3.3

when arguments are cells clear the locals slot (backport of #17927) [#17927]

Benjamin Peterson benjamin@python.org
date	Tue, 14 May 2013 22:31:26 -0500
parents	e2288953e9f1
children	bb8093e427f9 2bc63e65b3bf
files	Lib/test/test_scope.py Lib/test/test_super.py Misc/NEWS Objects/typeobject.c Python/ceval.c
diffstat	5 files changed, 63 insertions(+), 2 deletions(-)[+] [-] Lib/test/test_scope.py 29 Lib/test/test_super.py 13 Misc/NEWS 3 Objects/typeobject.c 12 Python/ceval.c 8

line wrap: on

line diff

--- a/Lib/test/test_scope.py +++ b/Lib/test/test_scope.py @@ -1,4 +1,6 @@ import unittest +import weakref + from test.support import check_syntax_error, cpython_only, run_unittest @@ -713,6 +715,33 @@ class ScopeTests(unittest.TestCase): def b(): global a

@cpython_only
def testCellLeak(self):
```
   # Issue 17927.[](#l1.16)
```
```
   #[](#l1.17)
```

   # The issue was that if self was part of a cycle involving the[](#l1.18)

   # frame of a method call, *and* the method contained a nested[](#l1.19)

   # function referencing self, thereby forcing 'self' into a[](#l1.20)

   # cell, setting self to None would not be enough to break the[](#l1.21)

   # frame -- the frame had another reference to the instance,[](#l1.22)

   # which could not be cleared by the code running in the frame[](#l1.23)

   # (though it will be cleared when the frame is collected).[](#l1.24)

   # Without the lambda, setting self to None is enough to break[](#l1.25)

```
   # the cycle.[](#l1.26)
```
```
   class Tester:[](#l1.27)
```
```
       def dig(self):[](#l1.28)
```
```
           if 0:[](#l1.29)
```
```
               lambda: self[](#l1.30)
```
```
           try:[](#l1.31)
```
```
               1/0[](#l1.32)
```

           except Exception as exc:[](#l1.33)

```
               self.exc = exc[](#l1.34)
```

           self = None  # Break the cycle[](#l1.35)

```
   tester = Tester()[](#l1.36)
```
```
   tester.dig()[](#l1.37)
```
```
   ref = weakref.ref(tester)[](#l1.38)
```
```
   del tester[](#l1.39)
```
```
   self.assertIsNone(ref())[](#l1.40)
```

def test_main():

--- a/Lib/test/test_super.py +++ b/Lib/test/test_super.py @@ -130,6 +130,19 @@ class TestSuper(unittest.TestCase): super() self.assertRaises(RuntimeError, X().f)

def test_cell_as_self(self):
```
   class X:[](#l2.8)
```
```
       def meth(self):[](#l2.9)
```
```
           super()[](#l2.10)
```

```
   def f():[](#l2.12)
```
```
       k = X()[](#l2.13)
```
```
       def g():[](#l2.14)
```
```
           return k[](#l2.15)
```
```
       return g[](#l2.16)
```
```
   c = f().__closure__[0][](#l2.17)
```

   self.assertRaises(TypeError, X.meth, c)[](#l2.18)

+ def test_main(): support.run_unittest(TestSuper)

--- a/Misc/NEWS +++ b/Misc/NEWS @@ -12,6 +12,9 @@ What's New in Python 3.3.2? Core and Builtins ----------------- +- Issue #17927: Frame objects kept arguments alive if they had been copied into

a cell, even if the cell was cleared. +

Issue #17237: Fix crash in the ASCII decoder on m68k.
Issue #17408: Avoid using an obsolete instance of the copyreg module when

--- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -6519,6 +6519,18 @@ super_init(PyObject *self, PyObject *arg return -1; } obj = f->f_localsplus[0];

   if (obj == NULL && co->co_cell2arg) {[](#l4.7)

       /* The first argument might be a cell. */[](#l4.8)

       n = PyTuple_GET_SIZE(co->co_cellvars);[](#l4.9)

       for (i = 0; i < n; i++) {[](#l4.10)

           if (co->co_cell2arg[i] == 0) {[](#l4.11)

               PyObject *cell = f->f_localsplus[co->co_nlocals + i];[](#l4.12)

               assert(PyCell_Check(cell));[](#l4.13)

               obj = PyCell_GET(cell);[](#l4.14)

```
               break;[](#l4.15)
```
```
           }[](#l4.16)
```
```
       }[](#l4.17)
```

   }[](#l4.18)
   if (obj == NULL) {[](#l4.19)
       PyErr_SetString(PyExc_RuntimeError,[](#l4.20)
                       "super(): arg[0] deleted");[](#l4.21)

--- a/Python/ceval.c +++ b/Python/ceval.c @@ -3403,10 +3403,14 @@ PyEval_EvalCodeEx(PyObject _co, PyObjec int arg; / Possibly account for the cell variable being an argument. */ if (co->co_cell2arg != NULL &&

       (arg = co->co_cell2arg[i]) != CO_CELL_NOT_AN_ARG)[](#l5.7)

       (arg = co->co_cell2arg[i]) != CO_CELL_NOT_AN_ARG) {[](#l5.8)
       c = PyCell_New(GETLOCAL(arg));[](#l5.9)

```
   else[](#l5.10)
```

       /* Clear the local copy. */[](#l5.11)

```
       SETLOCAL(arg, NULL);[](#l5.12)
```
```
   }[](#l5.13)
```

   else {[](#l5.14)
       c = PyCell_New(NULL);[](#l5.15)

   }[](#l5.16)
   if (c == NULL)[](#l5.17)
       goto fail;[](#l5.18)
   SETLOCAL(co->co_nlocals + i, c);[](#l5.19)