Commit a0bfa418 authored by Kirill Smelkov's avatar Kirill Smelkov

ZODB3: Pick backported patch for Persistent to release objects in __slots__ on ghostify

This is backported to ZODB-3.10 https://github.com/zopefoundation/persistent/pull/44

The patch is needed for wendelin.core to being able to relase not needed
memory.

/reviewed-on nexedi/slapos!93
parent f62e7340
From d387a425941b37b99355077657edf7a2f117cf47 Mon Sep 17 00:00:00 2001
From: Kirill Smelkov <kirr@nexedi.com>
Date: Thu, 21 Jul 2016 22:34:55 +0300
Subject: [PATCH] persistent: On deactivate release in-slots objects too
( This is backport of https://github.com/zopefoundation/persistent/pull/44
to ZODB-3.10 )
On ._p_deactivate() and ._p_invalidate(), when an object goes to ghost
state, objects referenced by all its attributes, except related to
persistence machinery, are released, this way freeing memory (if they
were referenced only from going-to-ghost object).
That's the idea - an object in ghost state is simply a stub, which loads
its content on first access (via hooking into get/set attr) while
occupying minimal memory in not-yet-loaded state.
However the above is not completely true right now, as currently on
ghostification only object's .__dict__ is released, while in-slots objects
are retained attached to ghost object staying in RAM:
---- 8< ----
from ZODB import DB
from persistent import Persistent
import gc
db = DB(None)
jar = db.open()
class C:
def __init__(self, v):
self.v = v
def __del__(self):
print 'released (%s)' % self.v
class P1(Persistent):
pass
class P2(Persistent):
__slots__ = ('aaa')
p1 = P1()
jar.add(p1)
p1.aaa = C(1)
p2 = P2()
jar.add(p2)
p2.aaa = C(2)
p1._p_invalidate()
# "released (1)" is printed
p2._p_invalidate()
gc.collect()
# "released (2)" is NOT printed <--
---- 8< ----
So teach ghostify() & friends to release objects in slots to free-up
memory when an object goes to ghost state.
NOTE PyErr_Occurred() added after ghostify() calls because
pickle_slotnames() can raise an error, but we do not want to change
ghostify() prototype for backward compatibility reason - as it is used
in cPersistenceCAPIstruct.
( I hit this bug with wendelin.core which uses proxies to load
data from DB to virtual memory manager and then deactivate proxy right
after load has been completed:
https://lab.nexedi.com/nexedi/wendelin.core/blob/f7803634/bigfile/file_zodb.py#L239
https://lab.nexedi.com/nexedi/wendelin.core/blob/f7803634/bigfile/file_zodb.py#L295 )
---
src/persistent/cPersistence.c | 41 +++++++++++++++++++++++++++++++++-
src/persistent/tests/testPersistent.py | 24 ++++++++++++++++++++
2 files changed, 64 insertions(+), 1 deletion(-)
diff --git a/src/persistent/cPersistence.c b/src/persistent/cPersistence.c
index b4a185c..28d1f9a 100644
--- a/src/persistent/cPersistence.c
+++ b/src/persistent/cPersistence.c
@@ -75,6 +75,7 @@ fatal_1350(cPersistentObject *self, const char *caller, const char *detail)
#endif
static void ghostify(cPersistentObject*);
+static PyObject * pickle_slotnames(PyTypeObject *cls);
/* Load the state of the object, unghostifying it. Upon success, return 1.
* If an error occurred, re-ghostify the object and return -1.
@@ -141,7 +142,7 @@ accessed(cPersistentObject *self)
static void
ghostify(cPersistentObject *self)
{
- PyObject **dictptr;
+ PyObject **dictptr, *slotnames;
/* are we already a ghost? */
if (self->state == cPersistent_GHOST_STATE)
@@ -171,6 +172,8 @@ ghostify(cPersistentObject *self)
_estimated_size_in_bytes(self->estimated_size);
ring_del(&self->ring);
self->state = cPersistent_GHOST_STATE;
+
+ /* clear __dict__ */
dictptr = _PyObject_GetDictPtr((PyObject *)self);
if (dictptr && *dictptr)
{
@@ -178,6 +181,38 @@ ghostify(cPersistentObject *self)
*dictptr = NULL;
}
+ /* clear all slots besides _p_* */
+ slotnames = pickle_slotnames(Py_TYPE(self));
+ if (slotnames && slotnames != Py_None)
+ {
+ int i;
+
+ for (i = 0; i < PyList_GET_SIZE(slotnames); i++)
+ {
+ PyObject *name;
+ char *cname;
+ int is_special;
+
+ name = PyList_GET_ITEM(slotnames, i);
+ if (PyBytes_Check(name))
+ {
+ cname = PyBytes_AS_STRING(name);
+ is_special = !strncmp(cname, "_p_", 3);
+ if (is_special) /* skip persistent */
+ {
+ continue;
+ }
+ }
+
+ /* NOTE: this skips our delattr hook */
+ if (PyObject_GenericSetAttr((PyObject *)self, name, NULL) < 0)
+ /* delattr of non-set slot will raise AttributeError - we
+ * simply ignore. */
+ PyErr_Clear();
+ }
+ }
+ Py_XDECREF(slotnames);
+
/* We remove the reference to the just ghosted object that the ring
* holds. Note that the dictionary of oids->objects has an uncounted
* reference, so if the ring's reference was the only one, this frees
@@ -261,6 +296,8 @@ Per__p_deactivate(cPersistentObject *self)
called directly. Methods that override this need to
do the same! */
ghostify(self);
+ if (PyErr_Occurred())
+ return NULL;
}
Py_INCREF(Py_None);
@@ -289,6 +326,8 @@ Per__p_invalidate(cPersistentObject *self)
if (Per_set_changed(self, NULL) < 0)
return NULL;
ghostify(self);
+ if (PyErr_Occurred())
+ return NULL;
}
Py_INCREF(Py_None);
return Py_None;
diff --git a/src/persistent/tests/testPersistent.py b/src/persistent/tests/testPersistent.py
index 51e0382..fdb8b67 100644
--- a/src/persistent/tests/testPersistent.py
+++ b/src/persistent/tests/testPersistent.py
@@ -180,6 +180,30 @@ class PersistenceTest(unittest.TestCase):
self.assertEqual(obj._p_changed, None)
self.assertEqual(obj._p_state, GHOST)
+ def test__p_invalidate_from_changed_w_slots(self):
+ from persistent import Persistent
+ class Derived(Persistent):
+ __slots__ = ('myattr1', 'myattr2')
+ def __init__(self):
+ self.myattr1 = 'value1'
+ self.myattr2 = 'value2'
+ obj = Derived()
+ jar = self._makeJar()
+ jar.add(obj)
+ obj._p_activate()
+ obj._p_changed = True
+ jar._loaded = []
+ jar._registered = []
+ self.assertEqual(Derived.myattr1.__get__(obj), 'value1')
+ self.assertEqual(Derived.myattr2.__get__(obj), 'value2')
+ obj._p_invalidate()
+ self.assertIs(obj._p_changed, None)
+ self.assertEqual(list(jar._loaded), [])
+ self.assertRaises(AttributeError, lambda: Derived.myattr1.__get__(obj))
+ self.assertRaises(AttributeError, lambda: Derived.myattr2.__get__(obj))
+ self.assertEqual(list(jar._loaded), [])
+ self.assertEqual(list(jar._registered), [])
+
def test_initial_serial(self):
NOSERIAL = "\000" * 8
obj = self._makeOne()
--
2.9.2.701.gf965a18.dirty
...@@ -45,6 +45,7 @@ eggs = neoppod[admin, ctl, master, storage-importer, storage-mysqldb, tests] ...@@ -45,6 +45,7 @@ eggs = neoppod[admin, ctl, master, storage-importer, storage-mysqldb, tests]
patch-binary = ${patch:location}/bin/patch patch-binary = ${patch:location}/bin/patch
ZODB3-patches = ZODB3-patches =
${:_profile_base_location_}/../../component/egg-patch/ZODB3-3.10.5.patch#c5fe331b1e3a930446f93ab4f6e97c6e ${:_profile_base_location_}/../../component/egg-patch/ZODB3-3.10.5.patch#c5fe331b1e3a930446f93ab4f6e97c6e
${:_profile_base_location_}/../../component/egg-patch/ZODB3-persistent-ghostify-slots.patch#3a66e9c018d7269bd522d5b0a746f510
ZODB3-patch-options = -p1 ZODB3-patch-options = -p1
[slapos-deps-eggs] [slapos-deps-eggs]
...@@ -105,7 +106,7 @@ md5sum = 81ab5e842ecf8385b12d735585497cc8 ...@@ -105,7 +106,7 @@ md5sum = 81ab5e842ecf8385b12d735585497cc8
[versions] [versions]
slapos.recipe.template = 2.9 slapos.recipe.template = 2.9
# patched egg # patched egg
ZODB3 = 3.10.5+SlapOSPatched001 ZODB3 = 3.10.5+SlapOSPatched002
# Required by slapos.toolbox = 0.57 # Required by slapos.toolbox = 0.57
slapos.toolbox = 0.57 slapos.toolbox = 0.57
apache-libcloud = 0.20.1 apache-libcloud = 0.20.1
......
...@@ -38,7 +38,7 @@ ZODB3-patches += ...@@ -38,7 +38,7 @@ ZODB3-patches +=
${neoppod-repository:location}/ZODB3.patch ${neoppod-repository:location}/ZODB3.patch
[versions] [versions]
ZODB3 = 3.10.5+SlapOSPatched002 ZODB3 = 3.10.5+SlapOSPatched003
erp5.util = 0.4.44 erp5.util = 0.4.44
# To match ERP5 # To match ERP5
transaction = 1.1.1 transaction = 1.1.1
......
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