Accessing CPU/RAM usage (like with Task Manager, but via API!)?

Question

Is there a specific way to access \"task manager\" information with the Windows API? I have done a fair bit of searching on the matter, but I can\'t seem to find an API call tha

Answer 1

Instead of calling the windows API directly you can use the psutil library which is a cross-platform library that provides a lot of information about processes. It works on Windows, Linux, Mac OS, BSD and Sun Solaris and works with python from 2.4 to 3.4 in both 32 and 64 bit fashion.

In particular it's Process class has the following interesting methods:

• cpu_times: user and system timings spent by the process from its start.
• cpu_percent: percentage of cpu utilization since last call or in the given interval
• memory_info: info about Ram and virtual memory usage. NOTE: the documentation explicitly states that these are the one shown by taskmgr.exe so it looks like exactly what you want.
• memory_info_ex: extended memory information.
• memory_percent: percentage of used memory by the process.

To iterate over all processes (in order to find the most CPU/memory hungry for example), you can just iterate over process_iter.

---

Here's a simple implementation of what you wanted to achieve:

import psutil

def most_intensive_process():
    return max(psutil.process_iter(), key=lambda x: x.cpu_percent(0))

def most_RAM_usage():
    return max(psutil.process_iter(), key=lambda x: x.memory_info()[0])

x = most_intensive_process()
y = most_RAM_usage()

print(x.name)
print(y.name)

Sample run on my system:

In [23]: def most_intensive_process():
    ...:     # psutil < 2.x has get_something style methods...
    ...:     return max(psutil.process_iter(), key=lambda x: x.get_cpu_percent(0))
    ...: 
    ...: def most_RAM_usage():
    ...:     return max(psutil.process_iter(), key=lambda x: x.get_memory_info()[0])

In [24]: x = most_intensive_process()
    ...: y = most_RAM_usage()
    ...: 

In [25]: print(x.name, y.name)
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Answer 2

You can retrieve information about RAM usage with the PSAPI functions, especially EnumProcesses to find all the processes in the system, and GetProcessMemoryInfo to get information about each process' memory usage.

You can retrieve CPU usage for each process with GetProcessTimes. This isn't always perfectly accurate, but I believe the Task Manager produces results that are inaccurate in the same way under the same circumstances.

In case you want it, information about memory usage by the system as a whole is available via GetPerformanceInfo.

Answer 3

You can use the following Windows API to retrieve various process counters in C/C++ program.

It retrieves information about the memory usage of the specified process.

BOOL WINAPI GetProcessMemoryInfo(
  _In_   HANDLE Process,
  _Out_  PPROCESS_MEMORY_COUNTERS ppsmemCounters,
  _In_   DWORD cb
);

There is complete example on MSDN, which explains how it can be used to retrieve such information for your process.

http://msdn.microsoft.com/en-us/library/windows/desktop/ms682050%28v=vs.85%29.aspx

You have mentioned that you would like to fetch the information on continuous basis(with some time interval as task manager do). To achieve this you may want to write the complete logic(mentioned in MSDN) inside a function and call it after some time delay(Sleep(1second)).This way you should be able to fetch all these information of your program till it executes.