《MYSQL數據庫深度解析MySQL啟動時報“The server quit without updating PID file”錯誤的原因》要點:
本文介紹了MYSQL數據庫深度解析MySQL啟動時報“The server quit without updating PID file”錯誤的原因,希望對您有用。如果有疑問,可以聯系我們。
很多童鞋在啟動mysql的時候,碰到過這個錯誤,MYSQL學習
首先,澄清一點,出現這個錯誤的前提是:通過服務腳本來啟動mysql.通過mysqld_safe或mysqld啟動mysql實例并不會報這個錯誤.MYSQL學習
那么,出現這個錯誤的原因具體是什么呢?MYSQL學習
哈哈,對分析過程不care的童鞋可直接跳到文末的總結部分~MYSQL學習
總結MYSQL學習
下面,來分析下mysql的服務啟動腳本MYSQL學習
腳本完整內容如下:MYSQL學習
#!/bin/sh # Copyright Abandoned 1996 TCX DataKonsult AB & Monty Program KB & Detron HB # This file is public domain and comes with NO WARRANTY of any kind # MySQL daemon start/stop script. # Usually this is put in /etc/init.d (at least on machines SYSV R4 based # systems) and linked to /etc/rc3.d/S99mysql and /etc/rc0.d/K01mysql. # When this is done the mysql server will be started when the machine is # started and shut down when the systems goes down. # Comments to support chkconfig on RedHat Linux # chkconfig: 2345 64 36 # description: A very fast and reliable SQL database engine. # Comments to support LSB init script conventions ### BEGIN INIT INFO # Provides: mysql # Required-Start: $local_fs $network $remote_fs # Should-Start: ypbind nscd ldap ntpd xntpd # Required-Stop: $local_fs $network $remote_fs # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: start and stop MySQL # Description: MySQL is a very fast and reliable SQL database engine. ### END INIT INFO # If you install MySQL on some other places than /usr/local/mysql, then you # have to do one of the following things for this script to work: # # - Run this script from within the MySQL installation directory # - Create a /etc/my.cnf file with the following information: # [mysqld] # basedir=<path-to-mysql-installation-directory> # - Add the above to any other configuration file (for example ~/.my.ini) # and copy my_print_defaults to /usr/bin # - Add the path to the mysql-installation-directory to the basedir variable # below. # # If you want to affect other MySQL variables, you should make your changes # in the /etc/my.cnf, ~/.my.cnf or other MySQL configuration files. # If you change base dir, you must also change datadir. These may get # overwritten by settings in the MySQL configuration files. basedir= datadir= # Default value, in seconds, afterwhich the script should timeout waiting # for server start. # Value here is overriden by value in my.cnf. # 0 means don't wait at all # Negative numbers mean to wait indefinitely service_startup_timeout=900 # Lock directory for RedHat / SuSE. lockdir='/var/lock/subsys' lock_file_path="$lockdir/mysql" # The following variables are only set for letting mysql.server find things. # Set some defaults mysqld_pid_file_path= if test -z "$basedir" then basedir=/usr/local/mysql bindir=/usr/local/mysql/bin if test -z "$datadir" then datadir=/usr/local/mysql/data fi sbindir=/usr/local/mysql/bin libexecdir=/usr/local/mysql/bin else bindir="$basedir/bin" if test -z "$datadir" then datadir="$basedir/data" fi sbindir="$basedir/sbin" libexecdir="$basedir/libexec" fi # datadir_set is used to determine if datadir was set (and so should be # *not* set inside of the --basedir= handler.) datadir_set= # # Use LSB init script functions for printing messages, if possible # lsb_functions="/lib/lsb/init-functions" if test -f $lsb_functions ; then . $lsb_functions else log_success_msg() { echo " SUCCESS! $@" } log_failure_msg() { echo " ERROR! $@" } fi PATH="/sbin:/usr/sbin:/bin:/usr/bin:$basedir/bin" export PATH mode=$1 # start or stop [ $# -ge 1 ] && shift other_args="$*" # uncommon, but needed when called from an RPM upgrade action # Expected: "--skip-networking --skip-grant-tables" # They are not checked here, intentionally, as it is the resposibility # of the "spec" file author to give correct arguments only. case `echo "testing\c"`,`echo -n testing` in *c*,-n*) echo_n= echo_c= ;; *c*,*) echo_n=-n echo_c= ;; *) echo_n= echo_c='\c' ;; esac parse_server_arguments() { for arg do case "$arg" in --basedir=*) basedir=`echo "$arg" | sed -e 's/^[^=]*=//'` bindir="$basedir/bin" if test -z "$datadir_set"; then datadir="$basedir/data" fi sbindir="$basedir/sbin" libexecdir="$basedir/libexec" ;; --datadir=*) datadir=`echo "$arg" | sed -e 's/^[^=]*=//'` datadir_set=1 ;; --pid-file=*) mysqld_pid_file_path=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; --service-startup-timeout=*) service_startup_timeout=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; esac done } wait_for_pid () { verb="$1" # created | removed pid="$2" # process ID of the program operating on the pid-file pid_file_path="$3" # path to the PID file. i=0 avoid_race_condition="by checking again" while test $i -ne $service_startup_timeout ; do case "$verb" in 'created') # wait for a PID-file to pop into existence. test -s "$pid_file_path" && i='' && break ;; 'removed') # wait for this PID-file to disappear test ! -s "$pid_file_path" && i='' && break ;; *) echo "wait_for_pid () usage: wait_for_pid created|removed pid pid_file_path" exit 1 ;; esac # if server isn't running, then pid-file will never be updated if test -n "$pid"; then if kill -0 "$pid" 2>/dev/null; then : # the server still runs else # The server may have exited between the last pid-file check and now. if test -n "$avoid_race_condition"; then avoid_race_condition="" continue # Check again. fi # there's nothing that will affect the file. log_failure_msg "The server quit without updating PID file ($pid_file_path)." return 1 # not waiting any more. fi fi echo $echo_n ".$echo_c" i=`expr $i + 1` sleep 1 done if test -z "$i" ; then log_success_msg return 0 else log_failure_msg return 1 fi } # Get arguments from the my.cnf file, # the only group, which is read from now on is [mysqld] if test -x ./bin/my_print_defaults then print_defaults="./bin/my_print_defaults" elif test -x $bindir/my_print_defaults then print_defaults="$bindir/my_print_defaults" elif test -x $bindir/mysql_print_defaults then print_defaults="$bindir/mysql_print_defaults" else # Try to find basedir in /etc/my.cnf conf=/etc/my.cnf print_defaults= if test -r $conf then subpat='^[^=]*basedir[^=]*=\(.*\)$' dirs=`sed -e "/$subpat/!d" -e 's//\1/' $conf` for d in $dirs do d=`echo $d | sed -e 's/[ ]//g'` if test -x "$d/bin/my_print_defaults" then print_defaults="$d/bin/my_print_defaults" break fi if test -x "$d/bin/mysql_print_defaults" then print_defaults="$d/bin/mysql_print_defaults" break fi done fi # Hope it's in the PATH ... but I doubt it test -z "$print_defaults" && print_defaults="my_print_defaults" fi # # Read defaults file from 'basedir'. If there is no defaults file there # check if it's in the old (depricated) place (datadir) and read it from there # extra_args="" if test -r "$basedir/my.cnf" then extra_args="-e $basedir/my.cnf" else if test -r "$datadir/my.cnf" then extra_args="-e $datadir/my.cnf" fi fi parse_server_arguments `$print_defaults $extra_args mysqld server mysql_server mysql.server` # # Set pid file if not given # if test -z "$mysqld_pid_file_path" then mysqld_pid_file_path=$datadir/`hostname`.pid else case "$mysqld_pid_file_path" in /* ) ;; * ) mysqld_pid_file_path="$datadir/$mysqld_pid_file_path" ;; esac fi case "$mode" in 'start') # Start daemon # Safeguard (relative paths, core dumps..) cd $basedir echo $echo_n "Starting MySQL" if test -x $bindir/mysqld_safe then # Give extra arguments to mysqld with the my.cnf file. This script # may be overwritten at next upgrade. $bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 & wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$? # Make lock for RedHat / SuSE if test -w "$lockdir" then touch "$lock_file_path" fi exit $return_value else log_failure_msg "Couldn't find MySQL server ($bindir/mysqld_safe)" fi ;; 'stop') # Stop daemon. We use a signal here to avoid having to know the # root password. if test -s "$mysqld_pid_file_path" then mysqld_pid=`cat "$mysqld_pid_file_path"` if (kill -0 $mysqld_pid 2>/dev/null) then echo $echo_n "Shutting down MySQL" kill $mysqld_pid # mysqld should remove the pid file when it exits, so wait for it. wait_for_pid removed "$mysqld_pid" "$mysqld_pid_file_path"; return_value=$? else log_failure_msg "MySQL server process #$mysqld_pid is not running!" rm "$mysqld_pid_file_path" fi # Delete lock for RedHat / SuSE if test -f "$lock_file_path" then rm -f "$lock_file_path" fi exit $return_value else log_failure_msg "MySQL server PID file could not be found!" fi ;; 'restart') # Stop the service and regardless of whether it was # running or not, start it again. if $0 stop $other_args; then $0 start $other_args else log_failure_msg "Failed to stop running server, so refusing to try to start." exit 1 fi ;; 'reload'|'force-reload') if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path" kill -HUP $mysqld_pid && log_success_msg "Reloading service MySQL" touch "$mysqld_pid_file_path" else log_failure_msg "MySQL PID file could not be found!" exit 1 fi ;; 'status') # First, check to see if pid file exists if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path" if kill -0 $mysqld_pid 2>/dev/null ; then log_success_msg "MySQL running ($mysqld_pid)" exit 0 else log_failure_msg "MySQL is not running, but PID file exists" exit 1 fi else # Try to find appropriate mysqld process mysqld_pid=`pidof $libexecdir/mysqld` # test if multiple pids exist pid_count=`echo $mysqld_pid | wc -w` if test $pid_count -gt 1 ; then log_failure_msg "Multiple MySQL running but PID file could not be found ($mysqld_pid)" exit 5 elif test -z $mysqld_pid ; then if test -f "$lock_file_path" ; then log_failure_msg "MySQL is not running, but lock file ($lock_file_path) exists" exit 2 fi log_failure_msg "MySQL is not running" exit 3 else log_failure_msg "MySQL is running but PID file could not be found" exit 4 fi fi ;; *) # usage basename=`basename "$0"` echo "Usage: $basename {start|stop|restart|reload|force-reload|status} [ MySQL server options ]" exit 1 ;; esac exit 0
首先,定義相關參數MYSQL學習
basedir= datadir= # Default value, in seconds, afterwhich the script should timeout waiting # for server start. # Value here is overriden by value in my.cnf. # 0 means don't wait at all # Negative numbers mean to wait indefinitely service_startup_timeout=900 # Lock directory for RedHat / SuSE. lockdir='/var/lock/subsys' lock_file_path="$lockdir/mysql"
其中,MYSQL學習
basedir 指的二進制壓縮包解壓后所在的目錄,譬如/usr/local/mysql.MYSQL學習
datadir 指的是數據目錄MYSQL學習
service_startup_timeout=900 定義mysql服務啟動的時間限制,如果在900s中沒有啟動成功,則該腳本會退出.MYSQL學習
lockdir='/var/lock/subsys'
關于/var/lock/subsys,網上的解釋如下,后續會用到.MYSQL學習
總的來說,系統關閉的過程(發出關閉信號,調用服務自身的進程)中會檢查/var/lock/subsys下的文件,逐一關閉每個服務,如果某一運行的服務在/var/lock/subsys下沒有相應的選項.在系統關閉的時候,會像殺死普通進程一樣殺死這個服務.MYSQL學習
通過察看/etc/rc.d/init.d下的腳本,可以發現每個服務自己操縱時都會去查看/var/lock/subsys下相應的服務.MYSQL學習
很多程序需要判斷是否當前已經有一個實例在運行,這個目錄就是讓程序判斷是否有實例運行的標志,比如說xinetd,如果存在這個文件,表示已經有xinetd在運行了,否則就是沒有,當然程序里面還要有相應的判斷措施來真正確定是否有實例在運行.通常與該目錄配套的還有/var/run目錄,用來存放對應實例的PID,如果你寫腳本的話,會發現這2個目錄結合起來可以很方便的判斷出許多服務是否在運行,運行的相關信息等等.?
MYSQL學習
判斷basedir和datadirMYSQL學習
# Set some defaults mysqld_pid_file_path= if test -z "$basedir" then basedir=/usr/local/mysql bindir=/usr/local/mysql/bin if test -z "$datadir" then datadir=/usr/local/mysql/data fi sbindir=/usr/local/mysql/bin libexecdir=/usr/local/mysql/bin else bindir="$basedir/bin" if test -z "$datadir" then datadir="$basedir/data" fi sbindir="$basedir/sbin" libexecdir="$basedir/libexec" fi
其中,MYSQL學習
mysqld_pid_file_path 指定pid文件的路徑MYSQL學習
-z string 判斷字符串是否為空MYSQL學習
如果basedir沒有顯示設置,則默認為/usr/local/mysql,這也是為什么很多mysql安裝教程都推薦將mysql相關文件放到/usr/local/mysql下.MYSQL學習
如果datadir沒有顯示設置,則默認為$basedir/data.MYSQL學習
定義log_success_msg()和log_failure_msg()函數MYSQL學習
首先,判斷/lib/lsb/init-functions文件是否存在,如果存在,則使定義在init-functions文件中的所有shell函數在當前腳本中生效.MYSQL學習
如果沒有,則定義兩個函數,一個用于打印成功日志,一個是打印錯誤日志.MYSQL學習
在RHCS 6.7中,該文件并不存在,已被/etc/init.d/functions所替代.MYSQL學習
# # Use LSB init script functions for printing messages, if possible # lsb_functions="/lib/lsb/init-functions" if test -f $lsb_functions ; then . $lsb_functions else log_success_msg() { echo " SUCCESS! $@" } log_failure_msg() { echo " ERROR! $@" } fi
傳遞參數MYSQL學習
將第一個參數傳遞給mode,剩下的參數傳遞給other_argsMYSQL學習
PATH="/sbin:/usr/sbin:/bin:/usr/bin:$basedir/bin" export PATH mode=$1 # start or stop [ $# -ge 1 ] && shift other_args="$*" # uncommon, but needed when called from an RPM upgrade action # Expected: "--skip-networking --skip-grant-tables" # They are not checked here, intentionally, as it is the resposibility # of the "spec" file author to give correct arguments only. case `echo "testing\c"`,`echo -n testing` in *c*,-n*) echo_n= echo_c= ;; *c*,*) echo_n=-n echo_c= ;; *) echo_n= echo_c='\c' ;; esac
解析配置文件中的參數MYSQL學習
這個函數在腳本后面會涉及到.MYSQL學習
主要涉及如下參數:--basedir,--datadir,--pid-file,--service-startup-timeout.MYSQL學習
parse_server_arguments() { for arg do case "$arg" in --basedir=*) basedir=`echo "$arg" | sed -e 's/^[^=]*=//'` bindir="$basedir/bin" if test -z "$datadir_set"; then datadir="$basedir/data" fi sbindir="$basedir/sbin" libexecdir="$basedir/libexec" ;; --datadir=*) datadir=`echo "$arg" | sed -e 's/^[^=]*=//'` datadir_set=1 ;; --pid-file=*) mysqld_pid_file_path=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; --service-startup-timeout=*) service_startup_timeout=`echo "$arg" | sed -e 's/^[^=]*=//'` ;; esac done }
判斷my_print_defaults的位置MYSQL學習
首先,它判斷當前路徑下的bin目錄中是否存在該可執行文件,如果不存在,則再判斷$bindir(通常指的是$basedir/bin)目錄下是否存在.MYSQL學習
如果還是沒有,則會判斷/etc/my.cnf是否存在并且可讀,如果是,則判斷該配置文件中是否指定了basedir參數,MYSQL學習
如果指定了,則取出該參數的值,并判斷該值對應的目錄中是否存在bin/my_print_defaults可執行文件MYSQL學習
最后一步,如果在上述目錄中實在沒發現my_print_defaults文件,MYSQL學習
索性就將print_defaults設置為"my_print_defaults",寄希望于該命令在當前的PATH環境中.MYSQL學習
# Get arguments from the my.cnf file, # the only group, which is read from now on is [mysqld] if test -x ./bin/my_print_defaults then print_defaults="./bin/my_print_defaults" elif test -x $bindir/my_print_defaults then print_defaults="$bindir/my_print_defaults" elif test -x $bindir/mysql_print_defaults then print_defaults="$bindir/mysql_print_defaults" else # Try to find basedir in /etc/my.cnf conf=/etc/my.cnf print_defaults= if test -r $conf then subpat='^[^=]*basedir[^=]*=\(.*\)$' dirs=`sed -e "/$subpat/!d" -e 's//\1/' $conf` for d in $dirs do d=`echo $d | sed -e 's/[ ]//g'` if test -x "$d/bin/my_print_defaults" then print_defaults="$d/bin/my_print_defaults" break fi if test -x "$d/bin/mysql_print_defaults" then print_defaults="$d/bin/mysql_print_defaults" break fi done fi # Hope it's in the PATH ... but I doubt it test -z "$print_defaults" && print_defaults="my_print_defaults" fi
查找默認的配置文件MYSQL學習
-r file 如果文件可讀,則為真MYSQL學習
# # Read defaults file from 'basedir'. If there is no defaults file there # check if it's in the old (depricated) place (datadir) and read it from there # extra_args="" if test -r "$basedir/my.cnf" then extra_args="-e $basedir/my.cnf" else if test -r "$datadir/my.cnf" then extra_args="-e $datadir/my.cnf" fi fi
解析配置文件中的參數MYSQL學習
my_print_defaults的用法如下:MYSQL學習
my_print_defaults --defaults-file=example.cnf client mysqlMYSQL學習
即讀取配置文件中,client和mysql部分的參數配置,MYSQL學習
具體在本腳本中,是讀取mysqld,server,mysql_server,mysql.server四個部分的配置參數.MYSQL學習
parse_server_arguments `$print_defaults $extra_args mysqld server mysql_server mysql.server`
設置pid file的路徑MYSQL學習
-z string 判斷字符串是否為空MYSQL學習
如果--pid-file沒有在讀取到的配置文件中設置或者腳本剛開始的mysqld_pid_file_path參數沒有設置,MYSQL學習
則pid file默認設置在datadir下,以主機名.pid命名.MYSQL學習
如果該參數設置了,還需要進一步判斷MYSQL學習
如果該參數中帶有斜杠,則代表給定的值帶有路徑,可直接使用.MYSQL學習
如果該參數中沒帶路徑,則代表給定的值只是pid的文件名,可將其設在datadir下.MYSQL學習
# # Set pid file if not given # if test -z "$mysqld_pid_file_path" then mysqld_pid_file_path=$datadir/`hostname`.pid else case "$mysqld_pid_file_path" in /* ) ;; * ) mysqld_pid_file_path="$datadir/$mysqld_pid_file_path" ;; esac fi
服務腳本start選項MYSQL學習
首先,切換到$basedir中MYSQL學習
其次,判斷$basedir/bin中的mysqld_safe是否是可執行文件,如果是,則啟動mysqld實例,如果不是,則報錯退出.MYSQL學習
那么,啟動流程又是如何實現的呢?MYSQL學習
首先,執行$bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 &命令,啟動mysqld實例.MYSQL學習
注意到沒有,mysqld_safe其實是在basedir中執行的,包括mysql初始化腳本mysql_install_db,也建議在basedir中執行,具體可參考:MYSQL學習
分析MariaDB初始化腳本mysql_install_dbMYSQL學習
然后通過wait_for_pid函數進行判斷,具體可見下文對于wait_for_pid函數的分析MYSQL學習
判斷完畢后,MYSQL學習
查看$lockdir目錄是否可寫,可寫的話,則在目錄上創建一個文件.MYSQL學習
case "$mode" in 'start') # Start daemon # Safeguard (relative paths, core dumps..) cd $basedir echo $echo_n "Starting MySQL" if test -x $bindir/mysqld_safe then # Give extra arguments to mysqld with the my.cnf file. This script # may be overwritten at next upgrade. $bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 & wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$? # Make lock for RedHat / SuSE if test -w "$lockdir" then touch "$lock_file_path" fi exit $return_value else log_failure_msg "Couldn't find MySQL server ($bindir/mysqld_safe)" fi ;;
wait_for_pid函數MYSQL學習
在利用mysqld_safe啟動mysql實例后,會調用該參數MYSQL學習
wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?
其中$!在shell中用于獲取最后運行的后臺Process的PID,具體在本例中,是mysqld_safe進程的pid.MYSQL學習
因為第一個參數是created,所以會執行test -s "$pid_file_path" && i='' && break
命令.MYSQL學習
-s file 如果文件的長度不為零,則為真MYSQL學習
該命令的意思是如果pid文件存在,則將變量i設置為空,并退出while循環.MYSQL學習
然后執行如下判斷,MYSQL學習
if test -z "$i" ; then log_success_msg return 0 else log_failure_msg return 1 fi
如果$i為空,則打印成功日志,并退出腳本,很顯然,在pid文件存在的情況下,會將變量i設置為空.MYSQL學習
再來看看pid文件不存在的情況MYSQL學習
首先,會判斷$pid是否不為空(即if test -n "$pid")MYSQL學習
如果不為空,則代表在執行完mysqld_safe后,已經捕捉到了該進程的pid.MYSQL學習
在這種情況下,進一步通過kill -0 "$pid"確認該進程是否存在.MYSQL學習
kill -0就是不發送任何信號,但是系統會進行錯誤檢查,所以經常用來檢查一個進程是否存在,當進程不存在時, kill -0 pid會返回錯誤MYSQL學習
如果該進程存在,則不執行任何操作,直接跳到如下操作MYSQL學習
echo $echo_n ".$echo_c" i=`expr $i + 1` sleep 1
將變量i加1,并sleep 1s.MYSQL學習
然后,繼續while循環,之所以這樣做,是考慮到mysqld_safe已經執行,但是mysqld實例還在啟動過程中,還沒創建好pid文件.MYSQL學習
一直到$1達到$service_startup_timeout定義的時長.MYSQL學習
如果在while循環的過程中,通過kill -0 "$pid"判斷到進程已經不存在了,MYSQL學習
則會再判斷一次,如果這次判斷的結果依舊是pid file不存在,且進程不存在,則會執行MYSQL學習
log_failure_msg "The server quit without updating PID file ($pid_file_path)."
這就是大名鼎鼎的“The server quit without updating PID file”的由來.MYSQL學習
wait_for_pid () { verb="$1" # created | removed pid="$2" # process ID of the program operating on the pid-file pid_file_path="$3" # path to the PID file. i=0 avoid_race_condition="by checking again" while test $i -ne $service_startup_timeout ; do case "$verb" in 'created') # wait for a PID-file to pop into existence. test -s "$pid_file_path" && i='' && break ;; 'removed') # wait for this PID-file to disappear test ! -s "$pid_file_path" && i='' && break ;; *) echo "wait_for_pid () usage: wait_for_pid created|removed pid pid_file_path" exit 1 ;; esac # if server isn't running, then pid-file will never be updated if test -n "$pid"; then if kill -0 "$pid" 2>/dev/null; then : # the server still runs else # The server may have exited between the last pid-file check and now. if test -n "$avoid_race_condition"; then avoid_race_condition="" continue # Check again. fi # there's nothing that will affect the file. log_failure_msg "The server quit without updating PID file ($pid_file_path)." return 1 # not waiting any more. fi fi echo $echo_n ".$echo_c" i=`expr $i + 1` sleep 1 done if test -z "$i" ; then log_success_msg return 0 else log_failure_msg return 1 fi }
服務腳本stop選項MYSQL學習
首先,判斷pid文件的長度是否不為零.MYSQL學習
-s file 如果文件的長度不為零,則為真MYSQL學習
此時,會通過pid文件獲取mysqld進程的pid,注意,不是mysqld_safe進程的pidMYSQL學習
然后,判斷mysqld進程是否在正常運行,MYSQL學習
如果是,則通過kill $mysqld_pid的方式來關閉mysqld進程MYSQL學習
殺死進程最安全的方法是單純使用kill命令,不加修飾符,不帶標志.
MYSQL學習
標準的kill命令通常會終止有問題的進程,并把進程的資源釋放給系統.然而,如果進程啟動了子進程,只殺死父進程,子進程仍在運行,因此仍消耗資源.為了防止這些所謂的“僵尸進程”,應確保在殺死父進程之前,先殺死其所有的子進程.
MYSQL學習
然后,調用wait_for_pid函數進行判斷,其實,wait_for_pid函數中設置avoid_race_condition變量的目的是為了stop選項,確實有可能出現,mysqld是在檢查pid file之后,檢查進程是否存活之前退出的.MYSQL學習
如果mysqld進程沒有正常運行,在會打印“MySQL server process #$mysqld_pid is not running!”信息,并刪除pid文件.MYSQL學習
如果在執行stop的時候,判斷pid文件的長度為0,則會打印"MySQL server PID file could not be found!"信息.MYSQL學習
所以,在pid文件不存在的情況下,通過服務腳本執行stop選項并不會關閉mysqld進程,這個時候,就可通過kill $mysqld_pid的方式來關閉mysqld進程.MYSQL學習
'stop') # Stop daemon. We use a signal here to avoid having to know the # root password. if test -s "$mysqld_pid_file_path" then mysqld_pid=`cat "$mysqld_pid_file_path"` if (kill -0 $mysqld_pid 2>/dev/null) then echo $echo_n "Shutting down MySQL" kill $mysqld_pid # mysqld should remove the pid file when it exits, so wait for it. wait_for_pid removed "$mysqld_pid" "$mysqld_pid_file_path"; return_value=$? else log_failure_msg "MySQL server process #$mysqld_pid is not running!" rm "$mysqld_pid_file_path" fi # Delete lock for RedHat / SuSE if test -f "$lock_file_path" then rm -f "$lock_file_path" fi exit $return_value else log_failure_msg "MySQL server PID file could not be found!" fi ;;
服務腳本restart選項MYSQL學習
首先,先執行stop操作,如果stop操作成功的話,則繼續執行start操作.MYSQL學習
如果stop操作失敗的話,則會輸出"Failed to stop running server, so refusing to try to start."信息,并退出腳本.MYSQL學習
'restart') # Stop the service and regardless of whether it was # running or not, start it again. if $0 stop $other_args; then $0 start $other_args else log_failure_msg "Failed to stop running server, so refusing to try to start." exit 1 fi ;;
服務腳本reload選項MYSQL學習
首先,判斷pid文件的長度是否為0,如果不為0,則將該文件中的值設置為mysqld_pid變量的值.MYSQL學習
然后對該進程執行kill -HUP操作.MYSQL學習
kill -HUP pid
pid 是進程標識.如果想要更改配置而不需停止并重新啟動服務,請使用該命令.在對配置文件作必要的更改后,發出該命令以動態更新服務配置.MYSQL學習
根據約定,當您發送一個掛起信號(信號 1 或 HUP)時,大多數服務器進程(所有常用的進程)都會進行復位操作并重新加載它們的配置文件.
MYSQL學習
如果pid文件的長度為0,則輸出"MySQL PID file could not be found!".MYSQL學習
'reload'|'force-reload') if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path" kill -HUP $mysqld_pid && log_success_msg "Reloading service MySQL" touch "$mysqld_pid_file_path" else log_failure_msg "MySQL PID file could not be found!" exit 1 fi ;;
服務腳本status選項MYSQL學習
首先,判斷pid文件長度是否為0,如果不是,則讀取該文件中的值,并判斷pid對應的進程是否運行正常,MYSQL學習
如果運行正常,則輸出"MySQL running"MYSQL學習
如果不正常,則輸出"MySQL is not running, but PID file exists"MYSQL學習
如果pid文件的長度為0,則試圖通過mysqld的啟動命令來獲取其pid,MYSQL學習
這個時候,可能存在一個mysqld程序啟動了多個實例,這會導致pid_count=`echo $mysqld_pid | wc -w`大于1.MYSQL學習
這個時候,會輸出"Multiple MySQL running but PID file could not be found"信息,并退出腳本.MYSQL學習
如果mysqld_pid為空,則會繼續判斷"$lock_file_path"是否存在,如果存在,MYSQL學習
則會輸出"MySQL is not running, but lock file ($lock_file_path) exists"信息.MYSQL學習
如果"$lock_file_path"不存在,則會輸出"MySQL is not running"信息.MYSQL學習
如果mysqld_pid等于1,則會輸出"MySQL is running but PID file could not be found"信息.MYSQL學習
'status') # First, check to see if pid file exists if test -s "$mysqld_pid_file_path" ; then read mysqld_pid < "$mysqld_pid_file_path" if kill -0 $mysqld_pid 2>/dev/null ; then log_success_msg "MySQL running ($mysqld_pid)" exit 0 else log_failure_msg "MySQL is not running, but PID file exists" exit 1 fi else # Try to find appropriate mysqld process mysqld_pid=`pidof $libexecdir/mysqld` # test if multiple pids exist pid_count=`echo $mysqld_pid | wc -w` if test $pid_count -gt 1 ; then log_failure_msg "Multiple MySQL running but PID file could not be found ($mysqld_pid)" exit 5 elif test -z $mysqld_pid ; then if test -f "$lock_file_path" ; then log_failure_msg "MySQL is not running, but lock file ($lock_file_path) exists" exit 2 fi log_failure_msg "MySQL is not running" exit 3 else log_failure_msg "MySQL is running but PID file could not be found" exit 4 fi fi ;;
服務腳本其它選項MYSQL學習
如果腳本的第一個參數不是上述幾個選項,則會輸出Usage信息.MYSQL學習
*) # usage basename=`basename "$0"` echo "Usage: $basename {start|stop|restart|reload|force-reload|status} [ MySQL server options ]" exit 1 ;;
至此,mysql的服務腳本分析完畢~MYSQL學習
總結MYSQL學習
在通過服務腳本啟動mysql的過程中,報“The server quit without updating PID file”錯誤,有兩個條件MYSQL學習
首先,pid文件不存在MYSQL學習
其次,通過kill -0 $pid檢查到進程并不存在MYSQL學習
這個時候,只能通過mysql數據庫的錯誤日志來定位.MYSQL學習
服務腳本如果不做任何調整的話,默認的basedir是/usr/local/mysql,datadir是/usr/local/mysql/dataMYSQL學習
如果自己的mysql服務均不是默認路徑,MYSQL學習
則需要在該腳本中顯式設置MYSQL學習
經測試,需設置如下幾處:MYSQL學習
1. 設置basedir和添加conf變量MYSQL學習
其中,conf指的是mysqld的配置文件,建議配置文件中顯式指定basedir和datadir的值.MYSQL學習
在這里,datadir可不設置,因為datadir可通過配置文件來獲取.MYSQL學習
但是basedir必須要指定,因為要首先根據basedir來判斷my_print_deefauts命令MYSQL學習
basedir=/usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64 datadir= conf=/usr/local/mysql-advanced-5.6.23-linux-glibc2.5-x86_64/my_3308.cnf
2. 第256行,添加extra_args=" -c $conf"
MYSQL學習
extra_args=" -e $basedir/my.cnf.bak" if test -r "$basedir/my.cnf" then extra_args="-e $basedir/my.cnf" else if test -r "$datadir/my.cnf" then extra_args="-e $datadir/my.cnf" fi fi extra_args=" -c $conf"
3. 修改285行mysqld_safe的啟動參數MYSQL學習
將MYSQL學習
$bindir/mysqld_safe --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 &
修改為,MYSQL學習
$bindir/mysqld_safe --defaults-file="$conf" --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null 2>&1 &
主要是添加了--defaults-file選項MYSQL學習
以上所述是小編給大家介紹的深度解析MySQL啟動時報“The server quit without updating PID file”錯誤的原因,希望對大家有所幫助,如果大家有任何疑問請給我留言,小編會及時回復大家的.在此也非常感謝大家對維易PHP網站的支持!MYSQL學習
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