如何以相当便携的方式以编程方式检查内存使用？(C/C++)

Question

我正在编写跨平台的C++代码(Windows,Mac).有没有办法检查当前进程使用了​​多少内存？一个非常人为的片段来说明:

unsigned long m0 = GetMemoryInUse();
char *p = new char[ random_number ];
unsigned long m1 = GetMemoryInUse();
printf( "%d bytes used\n", (m1-m0) );

当然(m1-m0)应该等于random_number,但我试图在更复杂的层面上做这件事,包括可能分配内存的库调用.

以下不是优选的:

1. 使用Valgrind(或其同类)
2. 使用自定义内存分配器来跟踪分配的内存.

Answer 1

这是我写的一些代码,试图以便携方式执行此操作.它并不完美,但我认为至少应该指出如何在几个平台上做到这一点.

(PS我经常使用OSX和Linux,并且知道这很有效.我很少使用Windows,所以警告适用于Windows子句,但我认为是正确的.)

#ifdef __linux__
# include <sys/sysinfo.h>
#endif

#ifdef __APPLE__
# include <mach/task.h>
# include <mach/mach_init.h>
#endif

#ifdef _WINDOWS
# include <windows.h>
#else
# include <sys/resource.h>
#endif

/// The amount of memory currently being used by this process, in bytes.
/// By default, returns the full virtual arena, but if resident=true,
/// it will report just the resident set in RAM (if supported on that OS).
size_t memory_used (bool resident=false)
{
#if defined(__linux__)
    // Ugh, getrusage doesn't work well on Linux.  Try grabbing info
    // directly from the /proc pseudo-filesystem.  Reading from
    // /proc/self/statm gives info on your own process, as one line of
    // numbers that are: virtual mem program size, resident set size,
    // shared pages, text/code, data/stack, library, dirty pages.  The
    // mem sizes should all be multiplied by the page size.
    size_t size = 0;
    FILE *file = fopen("/proc/self/statm", "r");
    if (file) {
        unsigned long vm = 0;
        fscanf (file, "%ul", &vm);  // Just need the first num: vm size
        fclose (file);
       size = (size_t)vm * getpagesize();
    }
    return size;

#elif defined(__APPLE__)
    // Inspired by:
    // http://miknight.blogspot.com/2005/11/resident-set-size-in-mac-os-x.html
    struct task_basic_info t_info;
    mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;
    task_info(current_task(), TASK_BASIC_INFO, (task_info_t)&t_info, &t_info_count);
    size_t size = (resident ? t_info.resident_size : t_info.virtual_size);
    return size;

#elif defined(_WINDOWS)
    // According to MSDN...
    PROCESS_MEMORY_COUNTERS counters;
    if (GetProcessMemoryInfo (GetCurrentProcess(), &counters, sizeof (counters)))
        return counters.PagefileUsage;
    else return 0;

#else
    // No idea what platform this is
    return 0;   // Punt
#endif
}

Answer 2

• 没有可移植的方法可以做到这一点。
• 对于大多数操作系统，甚至没有一种针对该操作系统的可靠方法。