Produces a CSV with

per_process_cpu_usage.py

import subprocess
import signal
import time
import sys
import csv

# This is set in the first call to run_top()
headers = []
def get_column_starts(headerStr):
    global headers
    # Top spaces things out evenly, which seems to be the only sane way to get
    # data from columns which may contain all sorts of data
    if len(headers) == 0:
        headers = filter(None, headerStr.split(' '))
    starts = []
    begin = 0
    for i in range(len(headers)):
        header = headers[i]
        if i == 0:
            start = 0
        else:
            start = headerStr.find(header, begin)
        starts.append(start)
        begin = start + len(header)
    return starts

def get_column_values(starts, columnStr):
    values = []
    for i in range(len(starts)):
        if i == len(starts)-1:
            values.append(columnStr[starts[i]:len(columnStr)].strip())
        else:
            values.append(columnStr[starts[i]:starts[i+1]].strip())
    return values

def parse_top(out):
    splitOut = out.split("\n")
    # Top has five lines of output, and then headers
    headerStr = splitOut[6]
    starts = get_column_starts(headerStr)
    parsedLines = []
    for line in splitOut[7:]:
        parsedLines.append(get_column_values(starts, line))
    return parsedLines

def run_top():
    proc = subprocess.Popen(["top","-b","-d1","-n1"],
    stdout=subprocess.PIPE)
    out, err = proc.communicate()
    return out

killed = False
def main():
    global headers
    if len(sys.argv) != 2:
        print("Usage is: %s <filename>" % sys.argv[0])
        return

    path = sys.argv[1]
    first_run = True
    while not killed:
        parsedOut = parse_top(run_top())
        now = time.time()

        if first_run:
            # Headers are set in the first call to run_top(), as they change per system
            with open(path, 'w+') as outfile:
                writer = csv.writer(outfile)
                writer.writerow(["TIME"] + headers)
            first_run = False

        with open(path, 'a+') as outfile:
            writer = csv.writer(outfile)
            for line in parsedOut:
                writer.writerow([now] + line)
        time.sleep(1)
        
    sys.exit(0)

def kill_handler(sig, frame):
    print('Terminating...')
    global killed
    killed = True

signal.signal(signal.SIGINT, kill_handler)
main()