C中当前进程的内存使用情况

Question

我需要在C中获取当前进程的内存使用情况.有人可以在Linux平台上提供如何执行此操作的代码示例吗？

我知道cat /proc/<your pid>/status获取内存的方法,但我不知道如何在C中捕获它.

顺便说一句,这是我正在修改的PHP扩展(授予,我是C新手).如果PHP扩展API中有可用的快捷方式,那将更有帮助.

Answer 1

的getrusage库函数返回包含一大堆有关当前进程,包括这些数据的结构:

long   ru_ixrss;         /* integral shared memory size */
long   ru_idrss;         /* integral unshared data size */
long   ru_isrss;         /* integral unshared stack size */

但是,最新的linux文档说明了这3个字段

(unmaintained) This field is currently unused on Linux

见getrusage(2)

Answer 2

您可以随时打开系统中的"文件",/proc就像使用常规文件一样(使用"自我"符号链接,这样您就不必查找自己的pid):

FILE* status = fopen( "/proc/self/status", "r" );

当然,您现在必须解析文件以选择所需的信息.

Answer 3

这是一种非常丑陋且不可移植的内存使用方式,但由于getrusage()的内存跟踪在Linux上基本无用,因此读取/ proc // statm是我知道在Linux上获取信息的唯一方法.

如果有人知道更清洁,或者更好的跨Unix方式跟踪内存使用情况,我会非常有兴趣学习如何.

typedef struct {
    unsigned long size,resident,share,text,lib,data,dt;
} statm_t;

void read_off_memory_status(statm_t& result)
{
  unsigned long dummy;
  const char* statm_path = "/proc/self/statm";

  FILE *f = fopen(statm_path,"r");
  if(!f){
    perror(statm_path);
    abort();
  }
  if(7 != fscanf(f,"%ld %ld %ld %ld %ld %ld %ld",
    &result.size,&result.resident,&result.share,&result.text,&result.lib,&result.data,&result.dt))
  {
    perror(statm_path);
    abort();
  }
  fclose(f);
}

从proc(5)手册页:

   /proc/[pid]/statm
          Provides information about memory usage, measured in pages.  
          The columns are:

              size       total program size
                         (same as VmSize in /proc/[pid]/status)
              resident   resident set size
                         (same as VmRSS in /proc/[pid]/status)
              share      shared pages (from shared mappings)
              text       text (code)
              lib        library (unused in Linux 2.6)
              data       data + stack
              dt         dirty pages (unused in Linux 2.6)

Answer 4

#include <sys/resource.h>
#include <errno.h>

errno = 0;
struct rusage* memory = malloc(sizeof(struct rusage));
getrusage(RUSAGE_SELF, memory);
if(errno == EFAULT)
    printf("Error: EFAULT\n");
else if(errno == EINVAL)
    printf("Error: EINVAL\n");
printf("Usage: %ld\n", memory->ru_ixrss);
printf("Usage: %ld\n", memory->ru_isrss);
printf("Usage: %ld\n", memory->ru_idrss);
printf("Max: %ld\n", memory->ru_maxrss);

我使用了这段代码,但出于某种原因,我总是为所有4个printf()得到0

Answer 5

我发现了这篇文章:http://appcrawler.com/wordpress/2013/05/13/simple-example-of-tracking-memory-using-getrusage/

简化版:

#include <sys/resource.h>
#include <stdio.h>

int main() {
  struct rusage r_usage;
  getrusage(RUSAGE_SELF,&r_usage);
  // Print the maximum resident set size used (in kilobytes).
  printf("Memory usage: %ld kilobytes\n",r_usage.ru_maxrss);
  return 0;
}

(在Linux 3.13中测试)

Answer 6

我参加聚会迟到了，但这可能对其他人在 linux 上寻找常驻和虚拟（以及迄今为止的峰值）内存有所帮助。

这可能很糟糕，但它完成了工作。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


/*
 * Measures the current (and peak) resident and virtual memories
 * usage of your linux C process, in kB
 */
void getMemory(
    int* currRealMem, int* peakRealMem,
    int* currVirtMem, int* peakVirtMem) {

    // stores each word in status file
    char buffer[1024] = "";

    // linux file contains this-process info
    FILE* file = fopen("/proc/self/status", "r");

    // read the entire file
    while (fscanf(file, " %1023s", buffer) == 1) {

        if (strcmp(buffer, "VmRSS:") == 0) {
            fscanf(file, " %d", currRealMem);
        }
        if (strcmp(buffer, "VmHWM:") == 0) {
            fscanf(file, " %d", peakRealMem);
        }
        if (strcmp(buffer, "VmSize:") == 0) {
            fscanf(file, " %d", currVirtMem);
        }
        if (strcmp(buffer, "VmPeak:") == 0) {
            fscanf(file, " %d", peakVirtMem);
        }
    }
    fclose(file);
}