我正在尝试序列化和反序列化 GHashTable JSON 和 valgrind 的输入和输出报告说这样做的结果肯定会丢失内存。 g_hash_table_new 有抑制在 glib.suppressions他们分发的文件，但没有 g_hash_table_new_full 的文件这是我看到的一堆。我的哈希表是 GObject已使用 g_param_spec_pointer 设置的属性，序列化它的函数是:
static JsonNode *
foo_obj_serialize_property (JsonSerializable *serializable,
const gchar *name,
const GValue *value,
GParamSpec *pspec)
{
JsonNode *retval = NULL;
if (g_strcmp0 (name, "list") == 0)
{
GHashTable *list = NULL;
GHashTableIter iter;
JsonArray *arr = NULL;
gpointer key, val;
retval = json_node_new (JSON_NODE_ARRAY);
g_return_val_if_fail (value != NULL, retval);
g_return_val_if_fail (G_VALUE_HOLDS_POINTER (value), retval);
list = g_value_get_pointer (value);
arr = json_array_new ();
if (list != NULL)
{
g_hash_table_iter_init (&iter, list);
while (g_hash_table_iter_next (&iter, &key, &val))
{
JsonNode *node = NULL;
JsonObject *obj = NULL;
FooItem *item;
item = FOO_ITEM (val);
node = json_gobject_serialize (G_OBJECT (item));
if (JSON_NODE_HOLDS_OBJECT (node))
{
obj = json_node_get_object (node);
json_array_add_object_element (arr, obj);
}
}
}
json_node_take_array (retval, arr);
}
return retval;
}
反序列化是:
static gboolean
foo_obj_deserialize_property (JsonSerializable *serializable,
const gchar *name,
GValue *value,
GParamSpec *pspec,
JsonNode *property_node)
{
gboolean retval = FALSE;
if (g_strcmp0 (name, "list") == 0)
{
GHashTable *list;
JsonArray *arr;
arr = json_node_get_array (property_node);
list = g_hash_table_new_full (g_str_hash,
g_str_equal,
g_free,
NULL);
for (gint i = 0; i < json_array_get_length (arr); i++)
{
g_autoptr (FooItem) item = NULL;
JsonNode *node = NULL;
node = json_array_get_element (arr, i);
item = FOO_ITEM (json_gobject_deserialize (FOO_TYPE_ITEM, node));
g_return_val_if_fail (FOO_IS_ITEM (item), FALSE);
g_object_ref (item);
g_hash_table_insert (list,
g_strdup (foo_item_get_key (item)),
item);
}
g_value_set_pointer (value, list);
retval = TRUE;
}
return retval;
}
我的GObject类属性获取/设置函数是:
static void
foo_obj_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
FooObj *self = FOO_OBJ (object);
switch (prop_id)
{
case PROP_LIST:
g_value_set_pointer (value, self->list);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
}
}
static void
foo_obj_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
FooObj *self = FOO_OBJ (object);
switch (prop_id)
{
case PROP_LIST:
foo_obj_set_list (self, g_value_get_pointer (value));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
}
}
最后是类的 getter/setter:
GHashTable *
foo_obj_get_list (FooObj *self)
{
GHashTable *list;
g_return_val_if_fail (FOO_IS_OBJ (self), NULL);
g_object_get (self, "list", &list, NULL);
return list;
}
void
foo_obj_set_list (FooObj *self,
GHashTable *list)
{
g_return_if_fail (FOO_IS_OBJ (self));
if (self->list == list)
return;
if (list)
g_hash_table_ref (list);
if (self->list)
g_hash_table_unref (self->list);
self->list = list;
g_object_notify_by_pspec (G_OBJECT (self), properties [PROP_LIST]);
}
我正在使用 valgrind --tool=memcheck --leak-check=full --show-leak-kinds=all --leak-resolution=high --num-callers=20 --suppressions=../tests/glib.supp foo 运行内存检查，并且我收到序列化内存丢失的消息，显示:
==24303== 32 bytes in 1 blocks are definitely lost in loss record 1,029 of 1,852
==24303== at 0x483877F: malloc (vg_replace_malloc.c:299)
==24303== by 0x494CAB1: g_malloc (in /usr/lib/libglib-2.0.so.0.6000.4)
==24303== by 0x492C8E4: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.6000.4)
==24303== by 0x4933839: g_slice_alloc0 (in /usr/lib/libglib-2.0.so.0.6000.4)
==24303== by 0x4D72CEE: json_node_alloc (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4D72D37: json_node_new (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4D77B37: json_gobject_serialize (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4867AC9: foo_item_serialize_property (foo-item.c:71)
==24303== by 0x4D779C1: ??? (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4D77B42: json_gobject_serialize (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4861681: foo_obj_serialize_property (foo-obj.c:146)
==24303== by 0x4D779C1: ??? (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4D77B42: json_gobject_serialize (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4D77B82: json_gobject_to_data (in /usr/lib/libjson-glib-1.0.so.0.400.4)
以及反序列化:
==24303== 184 (88 direct, 96 indirect) bytes in 1 blocks are definitely lost in loss record 1,774 of 1,852
==24303== at 0x483877F: malloc (vg_replace_malloc.c:299)
==24303== by 0x494CAB1: g_malloc (in /usr/lib/libglib-2.0.so.0.6000.4)
==24303== by 0x492C8E4: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.6000.4)
==24303== by 0x4966C5E: g_hash_table_new_full (in /usr/lib/libglib-2.0.so.0.6000.4)
==24303== by 0x4861AB2: foo_obj_deserialize_property (foo-obj.c:264)
==24303== by 0x4D77F00: ??? (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4D7826B: json_gobject_from_data (in /usr/lib/libjson-glib-1.0.so.0.400.4)
==24303== by 0x4862BEE: foo_obj_deserialize (foo-obj.c:472)
我很难看到我错过了什么，并且各种清除指针的尝试都会导致双重释放或关于引用计数== 0的错误。我知道有很多 GLib由于它处理内存的方式而受到抑制，但我不知道这些是否属于此范围。
我可能可以通过使用 json-glib 注册一个函数来对哈希表进行装箱并简化序列化，但除非需要，否则我不想朝那个方向发展。
最佳答案
node = json_gobject_serialize (G_OBJECT (item));
在这行之后，您不会对 node 执行任何操作，既不会将其存储在某个地方，也不会释放它。这会导致内存泄漏。另请注意，JsonNode 是 GBoxed，而不是 GObject。使用json-node-free释放它。
我还建议您阅读有关引用计数和 analysing valgrind output 的内容。 。
The stack trace tells you where the leaked memory was allocated. Memcheck cannot tell you why the memory leaked, unfortunately.
对于deserialize方法，它被分配在(foo-obj.c:264)，即g_hash_table_new_full。您创建一个哈希表，但不要销毁它。
关于c - JSON (GLib) 序列化泄漏 GHashTable 的内存，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/56980385/