Kürzlich stand ich vor dem Problem, dass einer meiner VPS Server immer vom Hoster gestoppt wurde. Dieses Problem tritt häufig auf, wenn bei einem 1 vCPU Server der CPU-load länger als 10 Minuten über 1.00 liegt.
Zur Lösung des Problems habe ich das Tool CPULIMIT entdeckt. Es gibt es auf Ubuntu & Centos / bereits als pre-kompiliertes Paket un kann einfach via apt-get oder yum installiert werden.
yum install cpulimit gawk
Im Anschluss habe ich ein Skript zu start eines Daemon hier /usr/bin/cpulimit_daemon.sh angelegt, mit diesem Inhalt:
#!/bin/bash
# ==============================================================
# CPU limit daemon - set PID's max. percentage CPU consumptions
# ==============================================================
# Variables
CPU_LIMIT=20 # Maximum percentage CPU consumption by each PID
DAEMON_INTERVAL=3 # Daemon check interval in seconds
BLACK_PROCESSES_LIST= # Limit only processes defined in this variable. If variable is empty (default) all violating processes are limited.
WHITE_PROCESSES_LIST= # Limit all processes except processes defined in this variable. If variable is empty (default) all violating processes are limited.
# Check if one of the variables BLACK_PROCESSES_LIST or WHITE_PROCESSES_LIST is defined.
if [[ -n "$BLACK_PROCESSES_LIST" && -n "$WHITE_PROCESSES_LIST" ]] ; then # If both variables are defined then error is produced.
echo "At least one or both of the variables BLACK_PROCESSES_LIST or WHITE_PROCESSES_LIST must be empty."
exit 1
elif [[ -n "$BLACK_PROCESSES_LIST" ]] ; then # If this variable is non-empty then set NEW_PIDS_COMMAND variable to bellow command
NEW_PIDS_COMMAND="top -b -n1 -c | grep -E '$BLACK_PROCESSES_LIST' | gawk '\$9>CPU_LIMIT {print \$1}' CPU_LIMIT=$CPU_LIMIT"
elif [[ -n "$WHITE_PROCESSES_LIST" ]] ; then # If this variable is non-empty then set NEW_PIDS_COMMAND variable to bellow command
NEW_PIDS_COMMAND="top -b -n1 -c | gawk 'NR>6' | grep -E -v '$WHITE_PROCESSES_LIST' | gawk '\$9>CPU_LIMIT {print \$1}' CPU_LIMIT=$CPU_LIMIT"
else
NEW_PIDS_COMMAND="top -b -n1 -c | gawk 'NR>6 && \$9>CPU_LIMIT {print \$1}' CPU_LIMIT=$CPU_LIMIT"
fi
# Search and limit violating PIDs
while sleep $DAEMON_INTERVAL
do
NEW_PIDS=$(eval "$NEW_PIDS_COMMAND") # Violating PIDs
LIMITED_PIDS=$(ps -eo args | gawk '$1=="cpulimit" {print $3}') # Already limited PIDs
QUEUE_PIDS=$(comm -23 <(echo "$NEW_PIDS" | sort -u) <(echo "$LIMITED_PIDS" | sort -u) | grep -v '^$') # PIDs in queue
for i in $QUEUE_PIDS
do
cpulimit -p $i -l $CPU_LIMIT -z & # Limit new violating processes
done
done
Um das Skript ausführen zu können müssen noch die Berechtigungen geändert werden:
chmod 755 /usr/bin/cpulimit_daemon.sh
Um nun den Job zu starten einfach ein Skript wie folgt unter /etc/init.d/cpulimit anlegen:
#!/bin/sh
#
# Script to start CPU limit daemon
#
set -e
case "$1" in
start)
if [ $(ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print $1}' | wc -l) -eq 0 ]; then
nohup /usr/bin/cpulimit_daemon.sh >/dev/null 2>&1 &
ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print}' | wc -l | gawk '{ if ($1 == 1) print " * cpulimit daemon started successfully"; else print " * cpulimit daemon can not be started" }'
else
echo " * cpulimit daemon can't be started, because it is already running"
fi
;;
stop)
CPULIMIT_DAEMON=$(ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print $1}' | wc -l)
CPULIMIT_INSTANCE=$(ps -eo pid,args | gawk '$2=="cpulimit" {print $1}' | wc -l)
CPULIMIT_ALL=$((CPULIMIT_DAEMON + CPULIMIT_INSTANCE))
if [ $CPULIMIT_ALL -gt 0 ]; then
if [ $CPULIMIT_DAEMON -gt 0 ]; then
ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print $1}' | xargs kill -9 # kill cpulimit daemon
fi
if [ $CPULIMIT_INSTANCE -gt 0 ]; then
ps -eo pid,args | gawk '$2=="cpulimit" {print $1}' | xargs kill -9 # release cpulimited process to normal priority
fi
ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print}' | wc -l | gawk '{ if ($1 == 1) print " * cpulimit daemon can not be stopped"; else print " * cpulimit daemon stopped successfully" }'
else
echo " * cpulimit daemon can't be stopped, because it is not running"
fi
;;
restart)
$0 stop
sleep 3
$0 start
;;
status)
ps -eo pid,args | gawk '$3=="/usr/bin/cpulimit_daemon.sh" {print}' | wc -l | gawk '{ if ($1 == 1) print " * cpulimit daemon is running"; else print " * cpulimit daemon is not running" }'
;;
esac
exit 0
Nun noch die Berechtigungen ändern:
chown root:root /etc/init.d/cpulimit
Um das Skript auf CentOs zu starten habe ich es einfach am ende von /etc/rc.config eingefügt. somit wird es nach dem Booten automatisch gestartet und limitiert dann die CPU intensiven Jobs.
Quelle: http://ubuntuforums.org/showthread.php?t=992706