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Total memory used by Python process?

Posted by: admin November 1, 2017 Leave a comment


Is there a way for a Python program to determine how much memory it’s currently using? I’ve seen discussions about memory usage for a single object, but what I need is total memory usage for the process, so that I can determine when it’s necessary to start discarding cached data.


On Windows, you can use WMI (home page, cheeseshop):

def memory():
    import os
    from wmi import WMI
    w = WMI('.')
    result = w.query("SELECT WorkingSet FROM Win32_PerfRawData_PerfProc_Process WHERE IDProcess=%d" % os.getpid())
    return int(result[0].WorkingSet)

On Linux (from python cookbook http://code.activestate.com/recipes/286222/:

import os
_proc_status = '/proc/%d/status' % os.getpid()

_scale = {'kB': 1024.0, 'mB': 1024.0*1024.0,
          'KB': 1024.0, 'MB': 1024.0*1024.0}

def _VmB(VmKey):
    global _proc_status, _scale
     # get pseudo file  /proc/<pid>/status
        t = open(_proc_status)
        v = t.read()
        return 0.0  # non-Linux?
     # get VmKey line e.g. 'VmRSS:  9999  kB\n ...'
    i = v.index(VmKey)
    v = v[i:].split(None, 3)  # whitespace
    if len(v) < 3:
        return 0.0  # invalid format?
     # convert Vm value to bytes
    return float(v[1]) * _scale[v[2]]

def memory(since=0.0):
    '''Return memory usage in bytes.
    return _VmB('VmSize:') - since

def resident(since=0.0):
    '''Return resident memory usage in bytes.
    return _VmB('VmRSS:') - since

def stacksize(since=0.0):
    '''Return stack size in bytes.
    return _VmB('VmStk:') - since


For Unixes (Linux, Mac OS X, Solaris) you could also use the getrusage() function from the standard library module resource. The resulting object has the attribute ru_maxrss, which gives peak memory usage for the calling process:

>>> resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
2656 # peak memory usage (bytes on OS X, kilobytes on Linux)

The Python docs aren’t clear on what the units are exactly, but the Mac OS X man page for getrusage(2) describes the units as bytes. The Linux man page isn’t clear, but it seems to be equivalent to the information from /proc/self/status, which is in kilobytes.

The getrusage() function can also be given resource.RUSAGE_CHILDREN to get the usage for child processes, and (on some systems) resource.RUSAGE_BOTH for total (self and child) process usage.

resource is a standard library module.

If you only care about Linux, you can just check the /proc/self/status file as described in a similar question.


Here is a useful solution that works for various operating systems, including Windows 7 x64:

import os
import psutil
process = psutil.Process(os.getpid())


On unix, you can use the ps tool to monitor it:

$ ps u -p 1347 | awk '{sum=sum+$6}; END {print sum/1024}'

where 1347 is some process id. Also, the result is in MB.


Heapy (and friends) may be what you’re looking for.

Also, caches typically have a fixed upper limit on their size to solve the sort of problem you’re talking about. For instance, check out this LRU cache decorator.


Using sh and os to get into python bayer’s answer.

float(sh.awk(sh.ps('u','-p',os.getpid()),'{sum=sum+$6}; END {print sum/1024}'))

Answer is in megabytes.


I like it, thank you for @bayer. I get a specific process count tool, now.

# Megabyte.
$ ps aux | grep python | awk '{sum=sum+$6}; END {print sum/1024 " MB"}'
87.9492 MB

# Byte.
$ ps aux | grep python | awk '{sum=sum+$6}; END {print sum " KB"}'
90064 KB

Attach my process list.

$ ps aux  | grep python
root       943  0.0  0.1  53252  9524 ?        Ss   Aug19  52:01 /usr/bin/python /usr/local/bin/beaver -c /etc/beaver/beaver.conf -l /var/log/beaver.log -P /var/run/beaver.pid
root       950  0.6  0.4 299680 34220 ?        Sl   Aug19 568:52 /usr/bin/python /usr/local/bin/beaver -c /etc/beaver/beaver.conf -l /var/log/beaver.log -P /var/run/beaver.pid
root      3803  0.2  0.4 315692 36576 ?        S    12:43   0:54 /usr/bin/python /usr/local/bin/beaver -c /etc/beaver/beaver.conf -l /var/log/beaver.log -P /var/run/beaver.pid
jonny    23325  0.0  0.1  47460  9076 pts/0    S+   17:40   0:00 python
jonny    24651  0.0  0.0  13076   924 pts/4    S+   18:06   0:00 grep python


han = win32api.OpenProcess(win32con.PROCESS_QUERY_INFORMATION|win32con.PROCESS_VM_READ, 0, os.getpid())
process_memory = int(win32process.GetProcessMemoryInfo(han)['WorkingSetSize'])