I am writing a Python script which downloads 4K videos and plays them on request. When my device memory goes above 7.2 GB it deletes the video with the least number of views.
Using the free command or top command I can get the memory information. But specifically, how do I get the total memory used? So that I can return this to the Python function to compare with the memory threshold.
14 Answers
You can also read the source of free's information, /proc/meminfo:
~ head /proc/meminfo
MemTotal: 4039168 kB
MemFree: 2567392 kB
MemAvailable: 3169436 kB
Buffers: 81756 kB
Cached: 712808 kB
SwapCached: 0 kB
Active: 835276 kB
Inactive: 457436 kB
Active(anon): 499080 kB
Inactive(anon): 17968 kBIn Python, for example:
with open('/proc/meminfo') as file: for line in file: if 'MemFree' in line: free_mem_in_kb = line.split()[1] breakwill get you the free memory in KB in the free_mem_in_kb variable. With something similar for total memory, you can subtract the values (or add up buffers, cached, etc.).
You could also create a dictionary of the values in the file:
from collections import namedtuple
MemInfoEntry = namedtuple('MemInfoEntry', ['value', 'unit'])
meminfo = {}
with open('/proc/meminfo') as file: for line in file: key, value, *unit = line.strip().split() meminfo[key.rstrip(':')] = MemInfoEntry(value, unit)Then retrieve the values with meminfo['MemAvailable'].value, for example.
Percentage used memory (excluding buffers and cache):
free | awk 'FNR == 3 {print $3/($3+$4)*100}'For your question you added: "above 7.2 gigabyte", but I would assume a percentage might be more flexible.
To expand on this, the same can be used for "percentage free memory":
free | awk 'FNR == 3 {print $4/($3+$4)*100}'awk is a pattern scanning tool with loads and loads of parameters. FNR is the input record number in the current input file. Basically the line that is currently processed. So FNR will scan for the 3rd line where the numbers are what you want. The $3 and $4 point to the 3rd and 4th column. If you want the number itself, use:
free | awk 'FNR == 3 {print $3}'
free | awk 'FNR == 3 {print $4}'Example:
$ free total used free shared buffers cached
Mem: 16419996 16144316 275680 0 447220 12589412
-/+ buffers/cache: 3107684 13312312
Swap: 16761852 38532 16723320
~$ free | awk 'FNR == 3 {print $3}'
3109056
~$ free | awk 'FNR == 3 {print $4}'
13311240If you want with buffers and cache: FNR=2. If you want swap, FNR=4.
muru's Python code intrigued me to use it in a decorator class to measure memory consumption of a function.
class memoryit: def FreeMemory(): with open('/proc/meminfo') as file: for line in file: if 'MemFree' in line: free_memKB = line.split()[1] return (float(free_memKB)/(1024*1024)) # returns GBytes float def __init__(self, function): # Decorator class to print the memory consumption of a self.function = function # function/method after calling it a number of iterations def __call__(self, *args, iterations = 1, **kwargs): before = memoryit.FreeMemory() for i in range (iterations): result = self.function(*args, **kwargs) after = memoryit.FreeMemory() print ('%r memory used: %2.3f GB' % (self.function.__name__, (before - after) / iterations)) return resultFunction to measure consumption:
@memoryit
def MakeMatrix (dim): matrix = [] for i in range (dim): matrix.append([j for j in range (dim)]) return (matrix)Usage:
print ("Starting memory:", memoryit.FreeMemory())
m = MakeMatrix(10000)
print ("Ending memory:", memoryit.FreeMemory() )Printout:
Starting memory: 10.58599853515625
'MakeMatrix' memory used: 3.741 GB
Ending memory: 6.864116668701172free --mega | awk 'FNR == 2 {print $7}' on terminal returns available memory in Mega.
One can call it from python.
This works for free verion: mfree from procps-ng 3.3.17
