Check Swap and Restart Service

'''
######################
checkswap.py
Author: Sheldon Alman
Date : Nov. 21 2013
######################
This script was specifically written as a workaround for the Samba memory leak issue.  The script checks the amount of swap space available and restarts the Samba process if the amount of swap available is less than the specified value.
######################
Revision History:
v0.1 - Nov 21 2013 - Initial Release
######################
'''
import subprocess
import re
import syslog

def write_syslog(level,message):
    '''This function writes the message passed to it at the corresponding log level to syslog'''
    try:
        syslog.syslog(level, message)
        return True
    except Exception, e:
        print "Cannot write to syslog ",e
        return False

def main():
    service = 'smb'
    total = subprocess.Popen(['/bin/grep','SwapTotal','/proc/meminfo'],stdout=subprocess.PIPE) #Total amount of swap space
    free = subprocess.Popen(['/bin/grep','SwapFree','/proc/meminfo'],stdout=subprocess.PIPE) #Amount of free swap space
    ps_aux = subprocess.Popen(['ps','aux'],stdout=subprocess.PIPE) #Executes the 'ps aux ' command and stores it's results
    grep_service = subprocess.Popen(['grep',service],stdin=ps_aux.stdout, stdout=subprocess.PIPE) #Executes the 'grep smb' command and takes stdout of 'ps aux' as it's input
    wc_service = subprocess.Popen(['wc','-l'],stdin=grep_service.stdout, stdout=subprocess.PIPE)
    wc_service_string = str(eval(str(wc_service.communicate()[0])) - 1)
    ps_aux.stdout.close()

    #Removes all other characters except for digits and converts the results to floating point numbers
    free_swap = float(re.findall(r'\d+', str(free.communicate()))[0])
    total_swap = float(re.findall(r'\d+', str(total.communicate()))[0])
    max_swap_usage = 75.0 #Max swap usage before service restart

    '''If the amount of free swap space is less than the specified number, write to syslog and restart the smb process.'''
    if (free_swap / total_swap * 100) < max_swap_usage:
        write_syslog(syslog.LOG_WARNING, "Swap usage is above %s%%.  Restarting %s service" % (max_swap_usage, service))
        write_syslog(syslog.LOG_WARNING, "Number of %s processes running : %s" % (service,wc_service_string))
        try:
            subprocess.check_call('/etc/init.d/%s restart' % (service), shell=True)
        except Exception, e:
            print "Could not execute ", e
            write_syslog(syslog.LOG_WARNING, "Could not restart %s service. Error: %s" % (service, e))
    else:
        write_syslog(syslog.LOG_INFO, "Swap usage is less than %s%%.  Restart of %s not required." % (max_swap_usage,service))

if __name__ == "__main__":
    main()