我如何解决内存泄漏,报告驻留在STL字符串
How do I solve memory leaks that are reported to reside in STL string?
对于一个学校项目,我们必须通过网络发送大文件。,我们必须使用Poco::XML。
在我们的文件通过网络发送后,似乎内存没有释放。
以下是接收部分~9 Mb
文件的示例:
valgrind --leak-check=full --show-reachable=yes -v ourExecutable parms
返回:
12,880,736 bytes in 37 blocks are definitely lost in loss record 101 of 101
at 0x4C2747E: operator new(unsigned long) (vg_replace_malloc.c:261)
by 0x5A3AC88: std::string::_Rep::_S_create(unsigned long, unsigned long, std::allocator<char> const&) (in /usr/lib64/gcc/x86_64-pc-linux-gnu/4.4.4/libstdc++.so.6.0.13)
by 0x5A3BC4A: std::string::_Rep::_M_clone(std::allocator<char> const&, unsigned long) (in /usr/lib64/gcc/x86_64-pc-linux-gnu/4.4.4/libstdc++.so.6.0.13)
by 0x5A3C1BB: std::string::reserve(unsigned long) (in /usr/lib64/gcc/x86_64-pc-linux-gnu/4.4.4/libstdc++.so.6.0.13)
by 0x5A3C68E: std::string::append(std::string const&) (in /usr/lib64/gcc/x86_64-pc-linux-gnu/4.4.4/libstdc++.so.6.0.13)
by 0x5202359: Poco::XML::Element::innerText() const (in /home/tomwij/IGS/trunk/Project/external/lib/libPocoXML.so.8)
by 0x4145BF: NodeProtocol::getChildNodeStrValue(Poco::XML::Element*, std::string) (NodeProtocol.cpp:82)
by 0x41544F: NodeProtocol::deserialize(std::string const&) (NodeProtocol.cpp:200)
by 0x40B088: Node::handleClientPacket(PriorityElement*) (Node.cpp:760)
by 0x40A04C: Node::handlePackets() (Node.cpp:574)
by 0x4078EA: Node::run() (Node.cpp:162)
by 0x40772D: Node::activate() (Node.cpp:138)
LEAK SUMMARY:
definitely lost: 12,888,036 bytes in 190 blocks
indirectly lost: 644,979 bytes in 1,355 blocks
possibly lost: 10,089 bytes in 27 blocks
still reachable: 306,020 bytes in 43 blocks
suppressed: 0 bytes in 0 blocks
在Poco前面的函数是
const string NodeProtocol::getChildNodeStrValue(Element * elem, string child)
{
Element* tempNode = elem->getChildElement(child);
XMLString result(tempNode->innerText());
string ret = string(fromXMLString(result));
result.clear();
return ret;
}
调用
XMLString Element::innerText() const
{
XMLString result;
Node* pChild = firstChild();
while (pChild)
{
result.append(pChild->innerText());
pChild = pChild->nextSibling();
}
return result;
}
(注意XMLString
为std::string
)
为什么STL字符串的append
泄漏内存?
如果我只是赋值而不是使用复制构造函数,它会给出同样的问题。
编辑:
我在Gentoo x64 (linux-2.6.34-gentoo-r12)上使用最新的稳定GNU GCC 4.4.4。
调用堆栈中的更多函数(剥离不相关的大块代码/if结构):
Command * NodeProtocol::deserialize(const string & msg)
{
DOMParser xmlParser;
// Get the root node.
AutoPtr<Document> doc = xmlParser.parseString(msg);
AutoPtr<Element> rootElement = doc->documentElement();
string root = fromXMLString(rootElement->nodeName());
string name = getChildNodeStrValue(rootElement, "name");
string data = getChildNodeStrValue(rootElement, "data");
return new PutCommand(name, data);
}
和
void Node::handleClientPacket(PriorityElement * prio)
{
Command * command = NodeProtocol::deserialize(prio->fPacket);
// CUT: Access some properties of command, let the command execute.
delete command;
}
和
void Node::handlePackets()
{
PriorityElement * prio = fQueue->top();
fQueue->pop();
if (prio->fSource == kCLIENT)
handleClientPacket(prio);
else if (prio->fSource == kNODE)
handleNodePacket(prio);
delete prio;
}
其中fQueue
为:
priority_queue< PriorityElement*, vector<PriorityElement*>, ComparisonFunction >
我想做一个评论,但显然我没有代表。您是否记得将Command
的析构函数设置为虚拟的?如果name
或data
是PutCommand
而不是Command
的域,并且Command
析构函数不是虚函数,那么在删除handleClientPacket
中的command
时,它们可能不会被正确释放。