最近想把公司的mysql5.5.43遷到mariadb10.0.21上，就在測試環境上搞了一把，具體步驟就不談了，還是蠻簡單的~但是到最後啟動mariadb的時候踩到坑了~

具體情況如下：

      從啟動介面來看MariaDB啟動不起？！！檢視程序看下：

     發現mysql程序已經起來了，但是不知道什麼原因給hang住了，不停的迴圈，再檢視我的日誌和埠

150924 16:57:51 mysqld_safe mysqld from pid file /data/mysql/data/mariadb.pid ended
150924 16:57:54 mysqld_safe Starting mysqld daemon with databases from /data/mysql/data
150924 16:57:54 [Note] /usr/sbin/mysqld (mysqld 10.0.21-MariaDB-log) starting as process 11356 ...
150924 16:57:54 [Note] InnoDB: Using mutexes to ref count buffer pool pages
150924 16:57:54 [Note] InnoDB: The InnoDB memory heap is disabled
150924 16:57:54 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
150924 16:57:54 [Note] InnoDB: Memory barrier is not used
150924 16:57:54 [Note] InnoDB: Compressed tables use zlib 1.2.3
150924 16:57:54 [Note] InnoDB: Using Linux native AIO
150924 16:57:54 [Note] InnoDB: Using CPU crc32 instructions
150924 16:57:54 [Note] InnoDB: Initializing buffer pool, size = 128.0M
150924 16:57:54 [Note] InnoDB: Completed initialization of buffer pool
150924 16:57:54 [Note] InnoDB: Highest supported file format is Barracuda.
150924 16:57:54 [Note] InnoDB: 128 rollback segment(s) are active.
150924 16:57:54 [Note] InnoDB: Waiting for purge to start
150924 16:57:54 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.25-73.1 started; log sequence number 1616817
150924 16:57:54 [Note] Plugin 'FEEDBACK' is disabled.
150924 16:57:54 [Note] Server socket created on IP: '::'.
150924 16:57:54 [Warning] 'user' entry '
 
[email protected]' ignored in --skip-name-resolve mode.
150924 16:57:54 [Warning] 'proxies_priv' entry '@% [email protected]' ignored in --skip-name-resolve mode.
150924 16:57:54 [Note] Event Scheduler: Loaded 0 events
150924 16:57:54 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.0.21-MariaDB-log'  socket: '/data/mysql/mysql.sock'  port: 3306  MariaDB Server
150924 16:57:54 [Note] Event Scheduler: scheduler thread started with id 2
 

檢視MariaDB10.0.21的mysql指令碼發現在啟動的時候會呼叫函式wait_for_ready

case "$mode" in
  'start')
    # Start daemon


    # 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" $other_args >/dev/null 2>&1 &
      wait_for_ready; return_value=$?

      # 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_ready () {

  i=0
  while test $i -ne $service_startup_timeout ; do

  i=0
  while test $i -ne $service_startup_timeout ; do

    if $bindir/mysqladmin ping >/dev/null 2>&1; then
          log_success_msg
      return 0
    elif kill -0 $! 2>/dev/null ; then
      :  # mysqld_safe is still running
    else
      # mysqld_safe is no longer running, abort the wait loop
      break
    fi

    echo $echo_n ".$echo_c"
    i=`expr $i + 1`
    sleep 1

  done

  log_failure_msg
  return 1
}

知道了原因，這裡面有兩種解決方法

1）在/etc/my.cnf中設定mysqladmin的使用者名稱，密碼和socket路徑

2）修改mysql啟動指令碼

這裡我採用的是修改mysql啟動指令碼，怕密碼洩露啊！參照mysql5.5中的check方式，check一下pid檔案就ok了

wait_for_ready () {

  i=0
  while test $i -ne $service_startup_timeout ; do

    #if $bindir/mysqladmin ping >/dev/null 2>&1; then
    if test -e $mysqld_pid_file_path;then
      log_success_msg
      return 0
    elif kill -0 $! 2>/dev/null ; then
      :  # mysqld_safe is still running
    else
      # mysqld_safe is no longer running, abort the wait loop
      break
    fi

    echo $echo_n ".$echo_c"
    i=`expr $i + 1`
    sleep 1

  done

  log_failure_msg
  return 1
}