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c++ - 如何避免意外的内存分配

转载 作者:太空宇宙 更新时间:2023-11-04 12:35:07 24 4
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我只是用c++写了一个小的MemoryHook库,作为preload使用。但是每次运行测试的时候,都分配了大量的内存,大小是72704。用法是这样的: LD_PRELOAD=./libPreload.so ./XXX

我试图在ldd列表中找到所有相关的库,但没有大小是72704。我删除了其他信息,只保留了大小,但也有这个问题。

我的初始化代码:

    static void TraceInitialize()
{
#ifdef _DEBUG
fprintf( stderr, "call TraceInitialize\n" );
#endif
pthread_mutex_lock( &s_mutexInit );
if ( s_status == TS_INITIALIZED ) { pthread_mutex_unlock( &s_mutexInit ); return; }

s_status = TS_INITIALIZING;

MemoryManager::initialize();

s_pRealMalloc = (FUNC_MALLOC)dlsym(RTLD_NEXT, "malloc");
s_pRealCalloc = (FUNC_CALLOC)dlsym(RTLD_NEXT, "calloc");
s_pRealRealloc = (FUNC_REALLOC)dlsym(RTLD_NEXT, "realloc");
s_pRealMemalign = (FUNC_MEMALIGN)dlsym(RTLD_NEXT, "memalign");
s_pRealValloc = (FUNC_VALLOC)dlsym(RTLD_NEXT, "valloc");
s_pRealFree = (FUNC_FREE)dlsym(RTLD_NEXT, "free");

assert( !( NULL == s_pRealMalloc || NULL == s_pRealCalloc || NULL == s_pRealRealloc ||
NULL == s_pRealMemalign || NULL == s_pRealValloc || NULL == s_pRealFree ) );

s_status = TS_INITIALIZED;

// printMap();

pthread_mutex_unlock( &s_mutexInit );
}

并跟踪 malloc 调用:

 static int s_no_hook = 0;
void* TraceMalloc( size_t size )
{
if ( s_status == TS_INITIALIZING ) return mockMemory::_mockMalloc( size );

if ( s_status != TS_INITIALIZED ) TraceInitialize();

void* p = _impMalloc( size, __sync_fetch_and_add( &s_no_hook, 1 ) );
__sync_fetch_and_sub( &s_no_hook, 1 );
return p;
}

当我测试一个 demo 问题时,只有一个空的 main 函数。我希望内存不会释放,但实际输出是:

++++++++++++++ unfreed addr: 0x55cc4ae22260, size: 72704, serial: 1 ++++++++++++++
backtrace:
./libPreLoad.so(_ZN11MemoryTrace13MemoryManager14storeBacktraceEPNS0_11tagUnitNodeE+0x28)[0x7f62fd6cceba]
./libPreLoad.so(_ZN11MemoryTrace13MemoryManager10appendUnitEPvmb+0x9f)[0x7f62fd6ccbb7]
./libPreLoad.so(_ZN11MemoryTrace10_impMallocEmb+0x52)[0x7f62fd6cd4cb]
./libPreLoad.so(_ZN11MemoryTrace11TraceMallocEm+0x58)[0x7f62fd6cd286]
./libPreLoad.so(malloc+0x18)[0x7f62fd6cc812]
/usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x8f416)[0x7f62fd1cd416]
/lib64/ld-linux-x86-64.so.2(+0x10733)[0x7f62fd9e0733]
/lib64/ld-linux-x86-64.so.2(+0x10ca)[0x7f62fd9d10ca]
++++++++++++++ end ++++++++++++++

没有回溯,输出是:

++++++++++++++ unfreed addr: 0x55f799c8e260, size: 72704, serial: 0 ++++++++++++++
backtrace:
++++++++++++++ end ++++++++++++++

还有一个额外的问题是无法统计静态全局变量的内存释放。我找不到合适的时间来做这个,即使有attribute ((destructor(101))) .

最佳答案

您看到的大分配是C++ STL。正如所问here通过 rerumuanswered通过 Nikos C.

The heap usage comes from the C++ standard library. It allocates memory for internal library use on startup. If you don't link against it, there should be zero difference between the C and C++ version. With GCC and Clang, you can compile the file with:

 g++ -Wl,--as-needed main.cpp 

This will instruct the linker to not link against unused libraries. In your example code, the C++ library is not used, so it should not link against the C++ standard library.

关于c++ - 如何避免意外的内存分配,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/56786196/

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