我正在使用clang编译器和libc ++标准库在C ++ 11中在mac上构建动态库。当我在我的测试代码上运行valgrind链接到我的动态库时，我得到一块肯定会丢失的内存。这是valgrind报告：
==45659== 36 bytes in 1 blocks are definitely lost in loss record 57 of 228
==45659== at 0x66BB: malloc (vg_replace_malloc.c:300)
==45659== by 0x31EAB0: __Balloc_D2A (in /usr/lib/system/libsystem_c.dylib)
==45659== by 0x31F2A5: __d2b_D2A (in /usr/lib/system/libsystem_c.dylib)
==45659== by 0x31BED6: __dtoa (in /usr/lib/system/libsystem_c.dylib)
==45659== by 0x3438A9: __vfprintf (in /usr/lib/system/libsystem_c.dylib)
==45659== by 0x36A2DA: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==45659== by 0x34FF66: _vsnprintf (in /usr/lib/system/libsystem_c.dylib)
==45659== by 0x34FFC5: vsnprintf_l (in /usr/lib/system/libsystem_c.dylib)
==45659== by 0x34057A: snprintf_l (in /usr/lib/system/libsystem_c.dylib)
==45659== by 0x10C75A: std::__1::num_put<char, std::__1::ostreambuf_iterator<char, std::__1::char_traits<char> > >::do_put(std::__1::ostreambuf_iterator<char, std::__1::char_traits<char> >, std::__1::ios_base&, char, double) const (in /usr/lib/libc++.1.dylib)
==45659== by 0xF3221: std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(double) (in /usr/lib/libc++.1.dylib)
==45659== by 0x12102: lmpsdata::header_data::write_dimension(std::__1::basic_ofstream<char, std::__1::char_traits<char> >&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) (header_data.cpp:75)
==45659==
==45659== LEAK SUMMARY:
==45659== definitely lost: 36 bytes in 1 blocks
==45659== indirectly lost: 0 bytes in 0 blocks
==45659== possibly lost: 0 bytes in 0 blocks
==45659== still reachable: 18,340 bytes in 215 blocks
==45659== suppressed: 25,274 bytes in 374 blocks
该特定代码段不处理我动态分配的任何内存，只使用STL对象和流。我已经附加了头文件和valgrind报告的方法导致泄漏。有人可以解释一下这里发生了什么吗？我绝对感到困惑。
header_data.h
#ifndef ____header_data__
#define ____header_data__
#include <string>
#include <fstream>
#include <cstdint>
#include <vector>
#include <map>
namespace lmpsdata {
class header_data
{//LAMMPS header information
//only the point particle header information has been implemented
//since the current atom base class is designed for point particles only
public:
header_data():xdim(2), ydim(2), zdim(2), tiltdim(3) {}
//methods
void read(const std::string &, const std::string &);
void write(std::ofstream &, const std::string &); //this write command will replace the one
std::string check_header_keyword(const std::string &, bool &);
uint64_t get(const std::string&);
std::vector<double>& get_vector(const std::string&);
void set(const std::string&, uint64_t);
void set_vector(const std::string&, std::vector<double>&);
private:
//methods
void read_dimension(const std::string&, const std::string&);
void write_dimension(std::ofstream&, const std::string&);
//members
uint64_t atomnum;
uint64_t bondnum;
uint64_t anglenum;
uint64_t dihedralnum;
uint64_t impropernum;
uint64_t atomtypenum;
uint64_t bondtypenum;
uint64_t angletypenum;
uint64_t dihedraltypenum;
uint64_t impropertypenum;
uint64_t extrabondnum;
std::vector<double> xdim;
std::vector<double> ydim;
std::vector<double> zdim;
std::vector<double> tiltdim;//for use with triclinic system
std::map<std::string, uint64_t&> int_map {
{"atoms", atomnum},
{"bonds", bondnum},
{"angles", anglenum},
{"dihedrals", dihedralnum},
{"impropers", impropernum},
{"atom types", atomtypenum},
{"bond types", bondtypenum},
{"angle types", angletypenum},
{"dihedral types", dihedraltypenum},
{"improper types", impropertypenum},
{"extra bond per atom", extrabondnum},
};
std::map<std::string, std::vector<double>&> v_map {
{"xlo xhi", xdim},
{"ylo yhi", ydim},
{"zlo zhi", zdim},
{"xy xz yz", tiltdim}
};
};
}
#endif /* defined(____header_data__) */
lmpsdata.cpp只显示write_dimension方法和文件的开头
#include "header_data.h"
#include <stdexcept>
using namespace lmpsdata;
void header_data::write_dimension(std::ofstream &file, const std::string& keyword)
{
std::vector<double>& data = v_map.at(keyword);
for (auto value: data) {
file << value << " ";
}
}
如果需要更多信息，请告知我们。
答案 0 :(得分：1)
您还没有提到您正在使用的OSX和valgrind的确切版本。我无法在我正在使用的版本上完全重现这一点（OSX 10.10; valgrind HEAD == Valgrind-3.11.0.SVN）。
这不在C++标准库中，而是在C库中。您应该能够使用简单的代码重现它（几乎相同）：
#include <stdio.h>
#include <xlocale.h>
int
main(int argc, char **argv)
{
locale_t loc = newlocale(LC_NUMERIC_MASK, "C", (locale_t)0);
double d = 22.22;
char buffer[1024];
snprintf_l(buffer, 1024, loc, "%f\n", d);
printf("%s", buffer);
freelocale(loc);
}
当使用valgrind --show-leak-kinds=all --leak-check=full ./leak运行时，我看到一些“仍然可以到达”的泄漏（在这种情况下，您的泄漏应显示实际泄漏）：
==26151== 32 bytes in 1 blocks are still reachable in loss record 28 of 85
==26151== at 0x10000850B: malloc (in /usr/local/Cellar/valgrind/HEAD/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
==26151== by 0x1002BC7DF: __Balloc_D2A (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002B9533: __rv_alloc_D2A (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002B9B3A: __dtoa (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002E1D52: __vfprintf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x10030A9AE: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002EF154: _vsnprintf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002EF1B3: vsnprintf_l (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002DF5F7: snprintf_l (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x100000ECA: main (leak.cpp:10)
==26151==
==26151== 36 bytes in 1 blocks are still reachable in loss record 30 of 85
==26151== at 0x10000850B: malloc (in /usr/local/Cellar/valgrind/HEAD/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
==26151== by 0x1002BC7DF: __Balloc_D2A (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002BD055: __d2b_D2A (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002B986B: __dtoa (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002E1D52: __vfprintf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x10030A9AE: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002EF154: _vsnprintf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002EF1B3: vsnprintf_l (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002DF5F7: snprintf_l (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x100000ECA: main (leak.cpp:10)
==26151==
==26151== 80 bytes in 1 blocks are still reachable in loss record 47 of 85
==26151== at 0x10000850B: malloc (in /usr/local/Cellar/valgrind/HEAD/lib/valgrind/vgpreload_memcheck-amd64-darwin.so)
==26151== by 0x1002BC736: __Balloc_D2A (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002BD055: __d2b_D2A (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002B986B: __dtoa (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002E1D52: __vfprintf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x10030A9AE: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002EF154: _vsnprintf (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002EF1B3: vsnprintf_l (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x1002DF5F7: snprintf_l (in /usr/lib/system/libsystem_c.dylib)
==26151== by 0x100000ECA: main (leak.cpp:10)
我对它进行了压制，因为它几乎无疑是一个真正的泄漏，完全不受你的控制。
查看已发布的OSX libc source，我无法看到错误存在的位置 - 320以后看起来都很好;基础代码似乎在必要时分配和释放。然而，这个错误可能已被引入并修复，因为我没有对所有来源进行详尽的拖网;有问题的文件是vfprintf.c，您正在查看dtoaresult分配＆amp;释放。
要确定您的libc版本，您可以执行以下操作：
$ otool -l /usr/lib/system/libsystem_c.dylib | grep -A5 ID_
在我的系统上，我得到输出：
cmd LC_ID_DYLIB
cmdsize 64
name /usr/lib/system/libsystem_c.dylib (offset 24)
time stamp 1 Thu Jan 1 01:00:01 1970
current version 1044.10.1
compatibility version 1.0.0
__vfprintf例程中似乎没有任何实际泄漏的代码路径出版来源。