Linux ps

How to keep track of how heavily a process is loading the cpu on a server.

Resources

• Ubuntu CronHowTo
• ollie845 cron
• top - HowToGeek
• GeeksforGeeks ps command
• NB:
  • TIME+ column displays minutes:seconds.fractions_of_seconds of cpu time since the process started.
  • ps shows days-hours:minutes:seconds of cpu time for each process since the process started.

Workflow

1. set up bash file to run ps and append data into file ~/monitor.process

	#!/bin/bash
	# filename monitor.process

	# run ps, append to monitorLogfile
	ps -f -U mysql -u mysql --no-headers >> mysql.monitor

2. Modify to add datetime stamp

	#!/bin/bash
	# monitorlogfile mysql.monitor
	
	# run ps, filter, append with datestamp to monitorLogfile
	
	DATESTAMP=`date +%y%m%d-%H%M%S`
	MONITOR=`ps -f -U mysql -u mysql --no-headers`
	echo $DATESTAMP $MONITOR >> mysql.monitor
		

3. Make file executable

	$ chmod 744 ~/monitor.process
	$

4. Set up cron to run this at set interval

	# use 'crontab -e' to add to your crontab
	$ crontab -e

	# new crontab entry:
	# run monitor.process 4 times per hour
	*/15 * * * * /home/ubuntu/monitor.process

5. Do something with log file, e.g.,
   1. Alert if getting too large
   2. Roll log file periodically, e.g.,
      1. Use cron to once a week rename log to dated log file (like mysql.monitor.210323).
      2. Next cron run will create a new log file.
      3. make sure not to run on 0,15,30,45 minute which could conflict with the 4 time per hour routing, above.