Poll a PID's state at 1ms resolution and aggregate the numbers

pidstate.py

#!/usr/bin/env python3

import math
import sys
import time

states = "RSDZTtWXxKWPI"

def get_state(pid):
    stat = open(f"/proc/{pid}/stat", "r").read().split(' ')
    return stat[2]

def format_stat(k, v, total, absolute=False):
    if absolute:
        return "%s:%4.1fs" % (k, v/1000)
    return "%s:%5.1f" % (k, 100*v/total)

def print_stats(stats, timediff=None):
    total = sum(stats.values())
    if total == 0:
        return ""
    absval = timediff is not None
    if absval:
        postfix = " (%0.1f seconds)" % timediff
    else:
        postfix = " (%d samples)" % total
    return "  ".join([format_stat(k, v, total, absval) for k, v in stats.items()][0:5]) + postfix

pid = sys.argv[1]
stats = dict.fromkeys(list(states), 0)
totals = dict.fromkeys(list(states), 0)

t0 = t = time.time()
try:
    while True:
        dt = time.time()*1000
        dt = 1 + math.floor(dt) - dt
        time.sleep(0.001*dt)
        t_ = time.time()
        if int(t) != int(t_):
            print(print_stats(stats))
            t = t_
            stats = dict.fromkeys(list(states), 0)
        state = get_state(pid)
        stats[state] += 1
        totals[state] += 1
except (FileNotFoundError, ProcessLookupError):
    print("PID %s not found" % sys.argv[1])
except KeyboardInterrupt:
    print()
if t != t0:
    print(print_stats(totals))
    print(print_stats(totals, timediff=t_ - t0))