cpython: f3706a9430da (original) (raw)

Mercurial > cpython

changeset 105739:f3706a9430da 3.6

Issue #19542: Fix bugs in WeakValueDictionary.setdefault() and WeakValueDictionary.pop() when a GC collection happens in another thread. Original patch and report by Armin Rigo. [#19542]

Antoine Pitrou solipsis@pitrou.net
date	Mon, 19 Dec 2016 10:58:14 +0100
parents	781c56168484(current diff)5a542a2bca08(diff)
children	ac2715d04119 da958d01755a
files	Lib/test/test_weakref.py Misc/NEWS
diffstat	3 files changed, 53 insertions(+), 5 deletions(-)[+] [-] Lib/test/test_weakref.py 41 Lib/weakref.py 13 Misc/NEWS 4

line wrap: on

line diff

--- a/Lib/test/test_weakref.py +++ b/Lib/test/test_weakref.py @@ -6,6 +6,7 @@ import weakref import operator import contextlib import copy +import time from test import support from test.support import script_helper @@ -72,6 +73,29 @@ class TestBase(unittest.TestCase): self.cbcalled += 1 +@contextlib.contextmanager +def collect_in_thread(period=0.0001):

"""
Ensure GC collections happen in a different thread, at a high frequency.
"""
threading = support.import_module('threading')
please_stop = False

def collect():
```
   while not please_stop:[](#l1.24)
```
```
       time.sleep(period)[](#l1.25)
```
```
       gc.collect()[](#l1.26)
```

with support.disable_gc():

   t = threading.Thread(target=collect)[](#l1.29)

```
   t.start()[](#l1.30)
```
```
   try:[](#l1.31)
```
```
       yield[](#l1.32)
```
```
   finally:[](#l1.33)
```
```
       please_stop = True[](#l1.34)
```
```
       t.join()[](#l1.35)
```

+ + class ReferencesTestCase(TestBase): def test_basic_ref(self): @@ -1636,6 +1660,23 @@ class MappingTestCase(TestBase): dict = weakref.WeakKeyDictionary() self.assertRegex(repr(dict), '<WeakKeyDictionary at 0x.*>')

def test_threaded_weak_valued_setdefault(self):

   d = weakref.WeakValueDictionary()[](#l1.46)

```
   with collect_in_thread():[](#l1.47)
```

       for i in range(100000):[](#l1.48)

           x = d.setdefault(10, RefCycle())[](#l1.49)

           self.assertIsNot(x, None)  # we never put None in there![](#l1.50)

```
           del x[](#l1.51)
```

def test_threaded_weak_valued_pop(self):

   d = weakref.WeakValueDictionary()[](#l1.54)

```
   with collect_in_thread():[](#l1.55)
```

       for i in range(100000):[](#l1.56)

```
           d[10] = RefCycle()[](#l1.57)
```
```
           x = d.pop(10, 10)[](#l1.58)
```

           self.assertIsNot(x, None)  # we never put None in there![](#l1.59)

+ + from test import mapping_tests class WeakValueDictionaryTestCase(mapping_tests.BasicTestMappingProtocol):

--- a/Lib/weakref.py +++ b/Lib/weakref.py @@ -239,24 +239,27 @@ class WeakValueDictionary(collections.Mu try: o = self.data.pop(key)() except KeyError:

```
       o = None[](#l2.7)
```

   if o is None:[](#l2.8)
       if args:[](#l2.9)
           return args[0][](#l2.10)

```
       raise[](#l2.11)
```
```
   if o is None:[](#l2.12)
```
```
       raise KeyError(key)[](#l2.13)
```

```
       else:[](#l2.14)
```

           raise KeyError(key)[](#l2.15)
   else:[](#l2.16)
       return o[](#l2.17)

def setdefault(self, key, default=None): try:

```
       wr = self.data[key][](#l2.21)
```

       o = self.data[key]()[](#l2.22)
   except KeyError:[](#l2.23)

```
       o = None[](#l2.24)
```

   if o is None:[](#l2.25)
       if self._pending_removals:[](#l2.26)
           self._commit_removals()[](#l2.27)
       self.data[key] = KeyedRef(default, self._remove, key)[](#l2.28)
       return default[](#l2.29)
   else:[](#l2.30)

```
       return wr()[](#l2.31)
```

```
       return o[](#l2.32)
```

def update(*args, **kwargs): if not args:

--- a/Misc/NEWS +++ b/Misc/NEWS @@ -38,6 +38,10 @@ Core and Builtins Library ------- +- Issue #19542: Fix bugs in WeakValueDictionary.setdefault() and

WeakValueDictionary.pop() when a GC collection happens in another
thread. +

Issue #20191: Fixed a crash in resource.prlimit() when pass a sequence that doesn't own its elements as limits.