我正在编写跨平台 C++ 代码（Windows、Mac）。有没有办法检查当前进程正在使用多少内存？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级别上执行此操作，包括可能分配内存的库调用。
以下是不可取的：
这是我编写的一些代码，试图以可移植的方式执行此操作。它并不完美，但我认为它至少应该指出如何在多个平台上执行此操作。
（PS 我经常使用 OSX 和 Linux，并且知道这很好用。我很少使用 Windows，所以注意事项适用于 Windows 条款，但我认为这是正确的。）
#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
}
我已经使用SIGAR API在主要平台上非常便携地获取各种与系统相关的信息。它也是开源的（Apache）。在这些相对琐碎但乏味的工作上，真的没有必要重新发明轮子。
你可以使用“内存池”模式。程序中的所有对象都从这个池中分配/释放内存，这样你就可以了解你消耗了多少内存。