Running Python script From php that create a thread and then kill it [closed]

I am a python newbie, very interested in raspberry pi and while I was crusading the code I had one idea, tried a lot of ways to make it but with no success.

I'm using this python script to get data from a gps receiver and send it to a database:

#! /usr/bin/python 
import os
from gps import *
from time import *
import time
import threading
import MySQLdb
import re

conn = MySQLdb.connect(host= "localhost",
                  user="root",
                  passwd="root",
                  db="gps")

gpsd = None #seting the global variable

os.system('clear') #clear the terminal (optional)

time_to_use = strftime("%Y_%m_%d-%H_%M_%S", gmtime())
time_to_use = "track_"+time_to_use


class GpsPoller(threading.Thread):
  def __init__(self):
    threading.Thread.__init__(self)
    global gpsd #bring it in scope
    gpsd = gps(mode=WATCH_ENABLE) #starting the stream of info
    self.current_value = None
    self.running = True #setting the thread running to true
    self.time = time.time();

  def run(self):
    global gpsd
    while gpsp.running:
      gpsd.next() 

if __name__ == '__main__':
  gpsp = GpsPoller() 

  try:
    gpsp.start() 
    while True:

       if gpsd.fix.mode>1:

          x = conn.cursor()

          # print gpsd.status
          # print 'mode        ' , gpsd.fix.mode

          try:
             x.execute("""INSERT INTO raw_data (`data`, `date`, `track`) VALUES (%s, CURRENT_TIMESTAMP, %s)""",(gpsd, time_to_use))
             conn.commit()
          except:
             conn.rollback()
             print 'error on mysql query'

       time.sleep(5) #set to whatever

  except (KeyboardInterrupt, SystemExit): #when you press ctrl+c
    print "\nKilling Thread..."
    conn.close()
    gpsp.running = False
    gpsp.join() # wait for the thread to finish what it's doing

  print "Done.\nExiting."
  exit(0)

I want to start and stop the script from an php file, already tried the next script, but it wont work, the python won't execute.

shell_exec('sudo python /var/www/gpsc.py > /dev/null &'); 

Can someone help me achieve the expected functionality?

I just want to call start.php and stop.php to start and stop the recording from the gps.

Best regards