Calculating process cpu usage by Python

Question

I'm trying to get (by a pid) the process cpu usage. I did some research about it and I found out that I can calculate it by using the GetSystemTimes() function. I found the calculation in this link: http://www.codeproject.com/Articles/10258/How-to-get-CPU-usage-of-processes-and-threads

And I need this code in Python But I don't know how to do this. So I found this code: https://sites.google.com/site/cadspython/home/modules/calcprocesscpuusage-py

I was trying to run it, and everything was working fine, but when I ran a little Python program (which took 28% from the cpu utilization), the code was showing me 100% and 98%. Which is not good.

So, I am asking for a code which calculate a process cpu usage by using the GetSystemTimes() function in Python (with pywin32).

Thanks in advance.

Answer 1

After a little more research I found the solution.

So in order to get the % of a process cpu usage we need some parameters:

1. System time

To calculate this we need user mode time, kernel mode time and idle mode time:

    from ctypes import *
    import time

    class FILETIME(Structure):
       _fields_ = [
          ("dwLowDateTime", DWORD),
          ("dwHighDateTime", DWORD)]

    def GetSystemTimes():
        """
        Uses the function GetSystemTimes() (win32) in order to get the user    mode time, kernel mode time and idle mode time
        :return: user time, kernel time and idle time (Dictinary)
        """

        __GetSystemTimes = windll.kernel32.GetSystemTimes
        idleTime, kernelTime, userTime = FILETIME(), FILETIME(), FILETIME()

        success = __GetSystemTimes(

        byref(idleTime),
        byref(kernelTime),
        byref(userTime))

        assert success, ctypes.WinError(ctypes.GetLastError())[1]

        return {
            "idleTime": idleTime.dwLowDateTime,
            "kernelTime": kernelTime.dwLowDateTime,
            "userTime": userTime.dwLowDateTime
           }


    def get_sys():  

        FirstSystemTimes = GetSystemTimes()
        time.sleep(SLEEP_TIME_1_5)
        SecSystemTimes = GetSystemTimes()

        """
         The total amount of time the system has operated since the last measurement is calculated by getting 
         kernel + user
        """

       usr = SecSystemTimes['userTime'] - FirstSystemTimes['userTime']
       ker = SecSystemTimes['kernelTime'] - FirstSystemTimes['kernelTime']
       idl = SecSystemTimes['idleTime'] - FirstSystemTimes['idleTime']

       sys = usr + ker
       return sys

2. Process user mode time and process kernel time

To get these parameters first we need to create a new process handle and then we will be able to get the process user mode time and process kernel time:

def cpu_process_util(pid):
    """
    Returns the process usage of CPU

    Source: http://www.philosophicalgeek.com/2009/01/03/determine-cpu-usage-of-current-process-c-and-c/
    :return: Process CPU usage (int)
    """

    # Creates a process handle
    proc = win32api.OpenProcess(ALL_PROCESS_ACCESS, False, pid)

    FirstProcessTimes = win32process.GetProcessTimes(proc)
    time.sleep(SLEEP_TIME_1_5)
    SecProcessTimes = win32process.GetProcessTimes(proc)

    """
     Process CPU usage is calculated by getting the total amount of time
     the system has operated since the last measurement
     made up of kernel + user) and the total
     amount of time the process has run (kernel + user).
    """

    proc_time_user_prev = FirstProcessTimes['UserTime']
    proc_time_kernel_prev = FirstProcessTimes['KernelTime']

    proc_time_user = SecProcessTimes['UserTime']
    proc_time_kernel = SecProcessTimes['KernelTime']

    proc_usr = proc_time_user - proc_time_user_prev
    proc_ker = proc_time_kernel - proc_time_kernel_prev

    proc_total_time = proc_usr + proc_ker

    return (100 * proc_total_time) / get_sys()