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对 memcache 大小增加的困惑

tag-icon • tag-icon java memcached memcache
对 memcache 大小增加的困惑

最近我的 memcache 出现了问题，因为我们收到了很多数据请求。因此，我使用 telnet 命令获取了有关 memcache 的一些统计数据。

对于生产环境，我看到有很多驱逐，这告诉我 memcache 内存不足。此外，从统计数据来看，缓存大小似乎只有 67MB（limit_maxbytes 67108864）或默认的 64MB。

这是来自我的生产 memcache 服务器的数据

stats
STAT pid 1579
STAT uptime 252639
STAT time 1600976110
STAT version 1.4.13
STAT libevent 1.4.13-stable
STAT pointer_size 64
STAT rusage_user 44411.308454
STAT rusage_system 56278.501367
STAT curr_connections 10
STAT total_connections 533
STAT connection_structures 11
STAT reserved_fds 20
STAT cmd_get 2397846230
STAT cmd_set 1913899024
STAT cmd_flush 0
STAT cmd_touch 0
STAT get_hits 482417633
STAT get_misses 1915428597
STAT delete_misses 0
STAT delete_hits 0
STAT incr_misses 0
STAT incr_hits 0
STAT decr_misses 0
STAT decr_hits 0
STAT cas_misses 0
STAT cas_hits 0
STAT cas_badval 0
STAT touch_hits 0
STAT touch_misses 0
STAT auth_cmds 0
STAT auth_errors 0
STAT bytes_read 221369814023
STAT bytes_written 53089737887
STAT limit_maxbytes 67108864
STAT accepting_conns 1
STAT listen_disabled_num 0
STAT threads 4
STAT conn_yields 50691561
STAT hash_power_level 19
STAT hash_bytes 4194304
STAT hash_is_expanding 0
STAT expired_unfetched 0
STAT evicted_unfetched 1614719615
STAT bytes 60253067
STAT curr_items 557392
STAT total_items 1911222415
STAT evictions 1910665023
STAT reclaimed 0
END

这是另一件事

$cat /etc/sysconfig/memcached
SERVERS=-lIPADDRESS:-p11211
CACHESIZE=1024

我没有文件 /etc/memcached.conf。但是这是来自 init.d 文件夹的 memcached 文件。

$ cat /etc/init.d/memcached 
#!/bin/bash
#
# memcached       This shell script takes care of starting and stopping
#                 the Memcached distributed memory object cache.
#
# chkconfig: - 60 40
# description:    Memcached is a distributed memory object cache system.
# processname:    memcached
# config:         /etc/sysconfig/memcached
# pidfile:        /var/run/memcached/memcached.pid

# Source function library.
. /etc/rc.d/init.d/functions

# Source networking configuration.
. /etc/sysconfig/network

# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 1

# Defines
DESC="the distributed memory object cache (memcached)"
PROG="memcached"
EXEC="/usr/sbin/${PROG}"
LOCK="/var/lock/subsys/${PROG}"
PIDF="/var/run/${PROG}/${PROG}.pid"
CONF="/etc/sysconfig/${PROG}"

# Include config
if [ -s /etc/sysconfig/${PROG} ]; then
  . /etc/sysconfig/${PROG}
fi

# Further defines
FSMAX="${FSMAX:-1024}"
RUN_AS="${RUN_AS:-memcached}"
SERVERS="${SERVERS:--l127.0.0.1:-p11211}"
OPTIONS="${OPTIONS} -u ${RUN_AS}"

# Check for binaries and configs
[ -x ${EXEC} ] || exit 5
[ -f ${CONF} ] || exit 6


start() {
    # Start daemon(s).
    COUNT=0
    ERR=0

    # Set max. filehandles
    ulimit -HSn ${FSMAX}

    for SRV in ${SERVERS}; do
      echo -n $"Starting ${DESC}: "
      OPTS=`echo ${SRV} | tr ':' ' '`
      let COUNT=${COUNT}+1

      daemon ${EXEC} -d -P ${PIDF} ${OPTS} ${OPTIONS}
      RETVAL=${?}

      [ ${RETVAL} -eq 0 ] || ERR=${COUNT}
      echo
    done

    [ ${ERR} -eq 0 ] && touch ${LOCK}
    return ${ERR}
}

stop() {
    # Stop daemon(s).
    echo -n $"Shutting down ${DESC}: "
    killproc ${PROG}
    RETVAL=${?}

    [ ${RETVAL} -eq 0 ] && rm -f ${LOCK} ${PIDF}
    echo
    return ${RETVAL}
}

restart() {
    stop
    sleep 2
    start
}

force_reload() {
    restart
}

rh_status() {
    status ${PROG}
}

rh_status_q() {
    rh_status >/dev/null 2>&1
}


# See how we were called.
case "${1}" in
    start)
    rh_status_q && exit 0
    ${1}
    ;;
    stop)
    rh_status_q || exit 0
    ${1}
    ;;
    restart)
    ${1}
    ;;
    force-reload)
    force_reload
    ;;
    status)
    rh_status
    ;;
    condrestart|try-restart)
    rh_status_q || exit 0
    restart
    ;;
    *)
    echo $"Usage: ${PROG} {start|stop|status|restart|try-restart|force-reload}"
    exit 2
esac
exit ${?}

对于非生产环境，我看到驱逐次数为 0，而且缓存大小似乎设置为 1GB（limit_maxbytes 1073741824）或 1024 MB。这是我的非生产服务器 memcache 统计数据

stats
STAT pid 1127
STAT uptime 50350278
STAT time 1600976701
STAT version 1.4.24
STAT libevent 1.4.13-stable
STAT pointer_size 64
STAT rusage_user 1384.501523
STAT rusage_system 1001.181797
STAT curr_connections 11
STAT total_connections 162
STAT connection_structures 16
STAT reserved_fds 20
STAT cmd_get 33072
STAT cmd_set 12565
STAT cmd_flush 0
STAT cmd_touch 0
STAT get_hits 20501
STAT get_misses 12571
STAT delete_misses 0
STAT delete_hits 0
STAT incr_misses 0
STAT incr_hits 0
STAT decr_misses 0
STAT decr_hits 0
STAT cas_misses 0
STAT cas_hits 0
STAT cas_badval 0
STAT touch_hits 0
STAT touch_misses 0
STAT auth_cmds 0
STAT auth_errors 0
STAT bytes_read 2298750
STAT bytes_written 9016176
STAT limit_maxbytes 1073741824
STAT accepting_conns 1
STAT listen_disabled_num 0
STAT threads 4
STAT conn_yields 0
STAT hash_power_level 16
STAT hash_bytes 524288
STAT hash_is_expanding 0
STAT malloc_fails 0
STAT bytes 1342698
STAT curr_items 12533
STAT total_items 12533
STAT expired_unfetched 0
STAT evicted_unfetched 0
STAT evictions 0
STAT reclaimed 0
STAT crawler_reclaimed 0
STAT crawler_items_checked 0
STAT lrutail_reflocked 0
END

这是另一件事

$cat /etc/sysconfig/memcached
SERVERS=-lIPADDRESS:-p11211
CACHESIZE=1024

我没有文件 /etc/memcached.conf。但是这是来自 init.d 文件夹的 memcached 文件。

$ cat /etc/init.d/memcached 
#! /bin/sh
#
# chkconfig: - 55 45
# description:  The memcached daemon is a network memory cache service.
# processname: memcached
# config: /etc/sysconfig/memcached
# pidfile: /var/run/memcached/memcached.pid

# Standard LSB functions
#. /lib/lsb/init-functions

# Source function library.
. /etc/init.d/functions

PORT=11211
USER=memcached
MAXCONN=1024
CACHESIZE=64
OPTIONS=""

if [ -f /etc/sysconfig/memcached ];then 
    . /etc/sysconfig/memcached
fi

# Check that networking is up.
. /etc/sysconfig/network

if [ "$NETWORKING" = "no" ]
then
    exit 0
fi

RETVAL=0
prog="memcached"
pidfile=${PIDFILE-/var/run/memcached/memcached.pid}
lockfile=${LOCKFILE-/var/lock/subsys/memcached}

start () {
    echo -n $"Starting $prog: "
    # Ensure that $pidfile directory has proper permissions and exists
    piddir=`dirname $pidfile`
    if [ ! -d $piddir ]; then
        mkdir $piddir
    fi
    if [ "`stat -c %U $piddir`" != "$USER" ]; then
        chown $USER $piddir
    fi

    daemon --pidfile ${pidfile} memcached -d -p $PORT -u $USER  -m $CACHESIZE -c $MAXCONN -P ${pidfile} $OPTIONS
    RETVAL=$?
    echo
    [ $RETVAL -eq 0 ] && touch ${lockfile}
}
stop () {
    echo -n $"Stopping $prog: "
    killproc -p ${pidfile} /usr/bin/memcached
    RETVAL=$?
    echo
    if [ $RETVAL -eq 0 ] ; then
        rm -f ${lockfile} ${pidfile}
    fi
}

restart () {
        stop
        start
}


# See how we were called.
case "$1" in
  start)
    start
    ;;
  stop)
    stop
    ;;
  status)
    status -p ${pidfile} memcached
    RETVAL=$?
    ;;
  restart|reload|force-reload)
    restart
    ;;
  condrestart|try-restart)
    [ -f ${lockfile} ] && restart || :
    ;;
  *)
    echo $"Usage: $0 {start|stop|status|restart|reload|force-reload|condrestart|try-restart}"
    RETVAL=2
        ;;
esac

exit $RETVAL

我对缓存大小值以及确切更新位置感到有些困惑。因为在非生产环境中，从统计数据来看缓存大小似乎是 1GB，从 /etc/sysconfig/memcached 来看是 1024MB (1GB)，但从 /etc/init.d/memcached 来看是 64MB。当我检查生产环境值时，从统计数据来看缓存大小是 67MB，从 /etc/sysconfig/memcached 来看是 1024MB (1GB)，而 /etc/init.d/memcached 中没有值，这让我假设该值默认为 64MB。

或者仅仅运行命令就会将缓存大小增加到 1GB。

 memcached -m 1024

但我想知道配置究竟使用了哪个文件。

谢谢您的帮助。

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