zookeeper启动脚本的bug

最近使用zookeeper发现, 首次启动zookeeper时, 都会遇到一个错误:

 

$ bin/zkServer.sh start

JMX enabled by default

Using config: /home/nauhcud/workspace/zookeeper/zookeeper/bin/../conf/zoo.cfg

Starting zookeeper ... bin/zkServer.sh: 162: cannot create /tmp/zookeeper/zookeeper_server.pid: Directory nonexistent

FAILED TO WRITE PID

 

查看进程发现zookeeper进程存在, 并可以正常使用. dataDir "/tmp/zookeeper/" 也在. 

 

kill掉zookeeper进程重新启动, 一切正常.

 

删掉dataDir, 问题依旧.

 

查看启动脚本, 发现start逻辑如下:

start)
 
  
...
 
  
 
     
    nohup $JAVA "-Dzookeeper.log.dir=${ZOO_LOG_DIR}" "-Dzookeeper.root.logger=${ZOO_LOG4J_PROP}" \
 
  
 
     
    -cp "$CLASSPATH" $JVMFLAGS $ZOOMAIN "$ZOOCFG" > "$_ZOO_DAEMON_OUT" 2>&1 < /dev/null &
 
  
 
     
    if [ $? -eq 0 ] 
 
  
 
     
    then
 
  
 
     
     
    if /bin/echo -n $! > "$ZOOPIDFILE"
 
  
 
     
     
    then
 
  
 
     
     
     
    sleep 1
 
  
 
     
     
     
    echo STARTED
 
  
 
     
     
    else
 
  
 
     
     
     
    echo FAILED TO WRITE PID  
    #这句说明写入Pid出现了问题
 
  
 
     
     
     
    exit 1
 
  
 
     
     
    fi  
 
 
...

纵观整个脚本, dataDir没有出现, 因此, dataDir应该是zookeeper进程内部建立的, 并且有一定延迟, 因此将zookeeper进程id写入到dataDir下的pidfile时, dataDir还没有建立好, 因此就出现了上述情况. 

 

解决办法很简单, 在写入pid之前先判断一下datadir是否存在, 让zookeeper有时间做完初始化, 然后再将pid写入即可.

start)
 
  
...
 
  
 
     
    nohup $JAVA "-Dzookeeper.log.dir=${ZOO_LOG_DIR}" "-Dzookeeper.root.logger=${ZOO_LOG4J_PROP}" \
 
  
 
     
    -cp "$CLASSPATH" $JVMFLAGS $ZOOMAIN "$ZOOCFG" > "$_ZOO_DAEMON_OUT" 2>&1 < /dev/null &
 
  
 
     
    zkpid=$!;
 
  
 
     
    if [ $? -eq 0 ] 
 
  
 
     
    then
 
  
 
     
      while [ ! -d `dirname $ZOOPIDFILE` ]
 
  
      do  
 
  
        sleep 1;
 
  
      done
 
  
 
     
     
    if /bin/echo -n $zkpid > "$ZOOPIDFILE"
 
  
 
     
     
    then
 
  
 
     
     
     
    sleep 1
 
  
 
     
     
     
    echo STARTED
 
  
 
     
     
    else
 
  
 
     
     
     
    echo FAILED TO WRITE PID
 
  
 
     
     
     
    exit 1
 
  
 
     
     
    fi  
 
  
...