mcsentinel.py

#!/usr/bin/env python

import os
import sys
import math
import random

NSECONDS = 5*3600
NNODES = 4000


#random_interval_max = 3600
random_interval_max = 1800

y = [ 0 for i in range( NSECONDS ) ]

nodestates = []

#random.seed( 1 )

ALGORITHM = 'INTERVAL'
#ALGORITHM = 'HOURLY'

def updateSchedule( t, state ):
    currentHour = t / 3600
    currentOffset = t % 3600
    if state['schedule'] is not None and state['schedule']['hour'] == currentHour:
        return
    nrunsperhour = 6.0
    nruns = int(nrunsperhour * (3600. - float(currentOffset)) / 3600.)
    offsets = [random.randint(min(3599, currentOffset + 1), 3599) for i in range(nruns)]
    offsets.sort()
    state['schedule'] = {'hour': currentHour,
                         'offsets': offsets}

def runThisTime( t, state ):
    currentHour = t / 3600
    currentOffset = t % 3600
    nexttime = None
    if len(state['schedule']['offsets']) > 0:
        offset = state['schedule']['offsets'][0]
        stime = 3600 * state['schedule']['hour'] + offset
        if t >= stime:
            nexttime = stime
    if nexttime is not None:
        state['schedule']['offsets'].pop(0)
        return True
    return False


for i in range( NNODES ):
    nodestates.append( { 'next_run_time': 0,
                         'schedule': None } )

for i in range( NSECONDS ):
    runCount = 0
    if ( i + 1 ) % 60 == 1:
        # Simulate cron running every minute
        for j in range( NNODES ):
            state = nodestates[j]
            if ALGORITHM == 'INTERVAL':
                if i >= state['next_run_time']:
                    #delay = random.randint( 0, 60 )
                    delay = 0
                    if i + delay < NSECONDS:
                        y[i+delay] += 1
                    state['next_run_time'] = i + random.randint( 1, random_interval_max )
            elif ALGORITHM == 'HOURLY':
                updateSchedule( i, state )
                if runThisTime( i, state ):
                    y[i] += 1

ofile = file( "mcsentinel-out.txt", "w" )
for i in range( 1, len( y ) ):
    ofile.write( "%d %d\n" % ( i, y[i] ) )
ofile.close()