删除单个对象时的内存泄漏,cpp

Question

我不知道为什么我在这里有内存泄漏,非常感谢任何建议.请注意,在进程终止之前,我调用destroy(),这是一个应该删除单例对象的静态成员函数.

这是相关的代码和valgrind的messaeg:

Manager.h:
class Manager {
public:
    // Constructor/destructor
    static Manager * instance();
    static void destroy();
    ~Manager();
        // Bunch of functions that I didn't write here

private:
    Manager();
    static Manager * _singleton; 
        // Bunch of fields that I didn't write here
};

Manager.cpp:
#include "Manager.h"

Manager * Manager::_singleton = NULL;

Manager * Manager::instance() {
    if (_singleton == NULL) {
            _singleton = new Manager();
        }
    return _singleton;
}

void Manager::destroy()
{
    delete _singleton;
    _singleton = NULL;
}

/*
 * Destructor
 */
Manager::~Manager() {
    // Deleting all fields here, memory leak is not from a field anyway
}

这是valgrind的报告:

==28688== HEAP SUMMARY:
==28688==     in use at exit: 512 bytes in 1 blocks
==28688==   total heap usage: 12 allocs, 11 frees, 10,376 bytes allocated
==28688== 
==28688== 512 bytes in 1 blocks are definitely lost in loss record 1 of 1
==28688==    at 0x4C27297: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==28688==    by 0x4014CE: Manager::Manager() (Manager.cpp:33)
==28688==    by 0x401437: Manager::instance() (Manager.cpp:15)
==28688==    by 0x4064E4: initdevice(char*) (outputdevice.cpp:69)
==28688==    by 0x406141: main (driver.cpp:21)
==28688== 
==28688== LEAK SUMMARY:
==28688==    definitely lost: 512 bytes in 1 blocks
==28688==    indirectly lost: 0 bytes in 0 blocks
==28688==      possibly lost: 0 bytes in 0 blocks
==28688==    still reachable: 0 bytes in 0 blocks
==28688==         suppressed: 0 bytes in 0 blocks

为什么我有这个泄漏？我确实删除_singleton了destroy()

正如我所说,我将不胜感激任何帮助,谢谢!

Answer 1

这里有几点需要注意.最明显的是:你什么时候打电话Manager::destroy.第二件事是内存valgrind 似乎在抱怨是在构造函数中分配的 Manager,你没有告诉我们.如果我们可以相信错误消息(我通常发现valgrind在这方面是可靠的,虽然它可以被欺骗),但是没有剩余的指向内存的指针; 要么你没有删除对象中的一个字段,要么对象在其构造函数中分配内存,而不是保存在字段中.

最后,通常更好的做法是不要破坏单身人士.单例成语的整个目的是避免初始化问题的顺序(在C++中,至少 - 否则,只声明对象的静态实例就足够了).破坏对象会引入可能的破坏问题顺序.如果你没有破坏它,valgrind会警告可能的内存泄漏(不是"明确丢失"); 您可以忽略警告,也可以将其过滤掉.