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mem_usage.cpp
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mem_usage.cpp
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/**
* @file mem_usage.cpp
* @author wangguibao([email protected])
* @date 2020/06/01 17:32:52
* @brief Get process memory usage.
* @ref https://stackoverflow.com/questions/669438/how-to-get-memory-usage-at-runtime-using-c/671389#671389
* @ref https://man7.org/linux/man-pages/man5/proc.5.html
**/
#include <unistd.h>
#include <ios>
#include <iostream>
#include <fstream>
#include <string>
//////////////////////////////////////////////////////////////////////////////
//
// process_mem_usage(double &, double &) - takes two doubles by reference,
// attempts to read the system-dependent data for a process' virtual memory
// size and resident set size, and return the results in KB.
//
// On failure, returns 0.0, 0.0
void process_mem_usage(double& vm_usage, double& resident_set)
{
using std::ios_base;
using std::ifstream;
using std::string;
vm_usage = 0.0;
resident_set = 0.0;
// 'file' stat seems to give the most reliable results
//
ifstream stat_stream("/proc/self/stat",ios_base::in);
// dummy vars for leading entries in stat that we don't care about
//
string pid, comm, state, ppid, pgrp, session, tty_nr;
string tpgid, flags, minflt, cminflt, majflt, cmajflt;
string utime, stime, cutime, cstime, priority, nice;
string O, itrealvalue, starttime;
// the two fields we want
//
unsigned long vsize;
long rss;
stat_stream >> pid >> comm >> state >> ppid >> pgrp >> session >> tty_nr
>> tpgid >> flags >> minflt >> cminflt >> majflt >> cmajflt
>> utime >> stime >> cutime >> cstime >> priority >> nice
>> O >> itrealvalue >> starttime >> vsize >> rss; // don't care about the rest
stat_stream.close();
long page_size_kb = sysconf(_SC_PAGE_SIZE) / 1024; // in case x86-64 is configured to use 2MB pages
vm_usage = vsize / 1024.0;
resident_set = rss * page_size_kb;
}
int main()
{
using std::cout;
using std::endl;
double vm, rss;
process_mem_usage(vm, rss);
cout << "VM: " << vm << "; RSS: " << rss << endl;
}
/* vim: set expandtab ts=4 sw=4 sts=4 tw=100: */