2.如果磁盘空间还很充足或配额也够,那么apache能产生’accept lock‘的另一个原因是 semaphore,
#ipcs -s 你将会看到
------ Semaphore Arrays --------
key semid owner perms nsems
0x00000000 68681743 apache 600 1
0x00000000 68714515 apache 600 1
0x00000000 68747291 apache 600 1
你可运行如下命令来安全的杀死每个 Semaphore
#ipcrm -s <semid>
<semid>是上面ipcs -s输出的第二列值。
想要一次性将所有的Semaphore全部杀死,请运行如下命令:
for semid in `ipcs -s |awk '{print $2}'`; do ip crm -s $semid; done
如果不能再创建更多的Semaphores:
有些时候你可能想改变系统允许创建 semaphores的数量。这就需要改变内核参数。
如果你在虚拟机上运行而不能改变内核参数,请联系你的主机提供商来改变这个参数。
运行以下命令来查看当前参数:
#ipcs -l
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 32768
max total shared memory (kbytes) = 8388608
min seg size (bytes) = 1
------ Semaphore Limits --------
max number of arrays = 1024
max semaphores per array = 250
max semaphores system wide = 256000
max ops per semop call = 32
semaphore max value = 32767
------ Messages: Limits --------
max queues system wide = 1024
max size of message (bytes) = 8192
default max size of queue (bytes) = 16384
修改 /etc/sysctl.conf文件,增加如下两行:
kernel.msgmni = 1024
kernel.sem = 250 256000 32 1024
运行命令# sysctl -p
使刚改的参数生效。
(kernel.msgmni 该文件指定消息队列标识的最大数目,即系统 范围内最大多少个消息队列。 缺省设置 : 16)
另外延伸到/var/lock/subsys作用
关于/var/lock/subsys目录
总的来说,系统关闭的过程(发出关闭信号,调用服务自身的进程)中会检查/var/lock/subsys
下的文件,逐一关闭每个服务,如果某一运行的服务在/var/lock/subsys下没有相应的选项。在
系统关闭的时候,会像杀死普通进程一样杀死这个服务。
通过察看/etc/rc.d/init.d下的脚本,可以发现每个服务自己操纵时都会去查看
/var/lock/subsys下相应的服务。
例如:
[root@rrd init.d]# pwd /etc/rc.d/init.d
[root@rrd init.d]# cat syslog #!/bin/sh # # syslog Starts syslogd/klogd. # # # chkconfig: 2345 30 99 # description: Syslog is the facility by which many daemons use to log # messages to various system log files. It is a good idea to always # run syslog. # securlevel: 90 # processname: syslogd klogd
# Source function library. . /etc/rc.d/init.d/functions
[ -f /sbin/syslogd ] || exit 0 [ -f /sbin/klogd ] || exit 0
if [ -f /etc/sysconfig/syslog ] then . /etc/sysconfig/syslog else SYSLOGD_OPTIONS="-m 0" KLOGD_OPTIONS="" fi
RETVAL=0
# See how we were called.
case "$1" in
start)
echo -n "Starting system logger: "
# we don't want the MARK ticks
daemon syslogd $SYSLOGD_OPTIONS
RETVAL=$?
echo
echo -n "Starting kernel logger: "
daemon klogd $KLOGD_OPTIONS
echo
[ $RETVAL -eq 0 ] && touch /var/lock/subsys/syslog
;;
stop)
echo -n "Shutting down kernel logger: "
killproc klogd
echo
echo -n "Shutting down system logger: "
killproc syslogd
RETVAL=$?
echo
[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/syslog
;;
status)
status syslogd
status klogd
RETVAL=$?
;;
restart|reload)
$0 stop
$0 start
RETVAL=$?
;;
*)
echo "Usage: syslog {start|stop|status|restart}"
exit 1
esac
exit $RETVAL
# cd /var/lock/subsys/ # ll syslog -rw-r--r-- 1 root root 0 Jan 27 19:20 syslog
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