How to Get the list of Running Processes using Python?

The operating system runs with hundreds of tasks/processes at a single time. As a Python developer, this is important because often while dealing with programs that consume huge amounts of memory, we may want to delete some unimportant tasks. This article will explore how to get the running process list using Python.

Using psutil Module

The psutil module is a powerful cross?platform library for system monitoring and process management in Python. It provides a convenient and consistent API to access system?related information, such as CPU usage, memory utilization, disk usage, network statistics, etc. Being cross?platform, the same code applies to all the operating systems.

Basic Process Listing

In the following code, we first import the psutil library. Next, we use the process_iter() method which returns all the processes running in the system ?

import psutil

processes = psutil.process_iter()
for process in processes:
    print(f"Process ID: {process.pid}, Name: {process.name()}")

Process ID: 1, Name: systemd
Process ID: 2, Name: kthreadd
Process ID: 3, Name: rcu_gp
Process ID: 4, Name: rcu_par_gp
Process ID: 5, Name: slub_flushwq
Process ID: 6, Name: netns
Process ID: 1234, Name: python
Process ID: 5678, Name: firefox

Getting Detailed Process Information

We can also retrieve additional information like CPU usage, memory usage, and process status ?

import psutil

for process in psutil.process_iter(['pid', 'name', 'cpu_percent', 'memory_percent']):
    try:
        info = process.info
        print(f"PID: {info['pid']}, Name: {info['name']}, CPU: {info['cpu_percent']}%, Memory: {info['memory_percent']:.2f}%")
    except (psutil.NoSuchProcess, psutil.AccessDenied):
        pass

PID: 1, Name: systemd, CPU: 0.0%, Memory: 0.12%
PID: 2, Name: kthreadd, CPU: 0.0%, Memory: 0.00%
PID: 1234, Name: python, CPU: 2.5%, Memory: 1.45%
PID: 5678, Name: firefox, CPU: 8.2%, Memory: 15.67%

Using Subprocess and Platform Module

Subprocess and platform modules are two important modules in Python that deal with the operating system. The subprocess allows the coders to interact with the operating system and execute external commands. The platform module gives us information about the current operating system.

Cross-Platform Process Listing

We can use different system commands based on the operating system to list processes ?

import subprocess
import platform

command = ""
if platform.system() == "Windows":
    command = "tasklist"
elif platform.system() == "Linux":
    command = "ps aux"
elif platform.system() == "Darwin":  # macOS
    command = "ps aux"

try:
    output = subprocess.check_output(command, shell=True, text=True)
    print(output)
except subprocess.CalledProcessError as e:
    print(f"Error executing command: {e}")

USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root           1  0.0  0.0 168556 13420 ?        Ss   09:37   0:01 /sbin/init splash
root           2  0.0  0.0      0     0 ?        S    09:37   0:00 [kthreadd]
root           3  0.0  0.0      0     0 ?        I<   09:37   0:00 [rcu_gp]
user        1234  2.5  1.4  45632 23456 ?        S    10:30   0:05 python script.py
user        5678  8.2 15.6 567890 98765 ?        S    09:45   2:34 firefox

Using wmi Module (Windows Only)

The WMI (Windows Management Instrumentation) is a Python library to interact with only Windows?based systems. It provides a Python interface to access and manipulate WMI data, allowing you to retrieve information about hardware, software, processes, and more.

Example

This code works only on Windows systems and requires the wmi module to be installed ?

import wmi

wmi_obj = wmi.WMI()
processes = wmi_obj.Win32_Process()

for process in processes:
    print(f"Process ID: {process.ProcessId}, Name: {process.Name}")

Process ID: 0, Name: System Idle Process
Process ID: 4, Name: System
Process ID: 76, Name: Registry
Process ID: 244, Name: smss.exe
Process ID: 328, Name: csrss.exe
Process ID: 1234, Name: python.exe
Process ID: 5678, Name: firefox.exe

Comparison of Methods

Conclusion

The psutil module is the recommended approach for cross-platform process monitoring due to its rich features and consistent API. Use subprocess with built-in modules when you can't install external libraries, and wmi for Windows-specific advanced features.