Analysis of PID examples in HDFS

This article mainly introduces the HDFS PID example analysis, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

Foreword:

In Linux, you can find the corresponding process number and process directory through PID. Ps-ef | grep pid can separately kill the desired pid; of kill. If you want to kill `process-ef | grep service name directly through the shell script on production, all multiple processes and other processes under the service will be kill. For example, hadoop can read the process number in the file to specify kill'.

The default PID storage path of Hodoop is / tmp,PID. The content is the process number.

Why is the PID content the process number:

[hadoop@hadoop001 hadoop] $jps

7857 DataNode

7748 NameNode

8774 Jps

8061 SecondaryNameNode

[hadoop@hadoop001 tmp] $pwd

/ tmp

[hadoop@hadoop001 tmp] $cat hadoop-hadoop-datanode.pid

7857

[hadoop@hadoop001 tmp] $cat hadoop-hadoop-namenode.pid

7748

[hadoop@hadoop001 tmp] $cat hadoop-hadoop-secondarynamenode.pid

8061

Observe the script stopped by hadoop and find that the script is stopped by calling hadoop-daemons.sh

[hadoop@hadoop001 sbin] $cat stop-dfs.sh

#

# namenodes

NAMENODES=$ ($HADOOP_PREFIX/bin/hdfs getconf-namenodes)

Echo "Stopping namenodes on [$NAMENODES]"

"$HADOOP_PREFIX/sbin/hadoop-daemons.sh"\

-config "$HADOOP_CONF_DIR"\

-hostnames "$NAMENODES"\

Script "$bin/hdfs" stop namenode

#

# datanodes (using default slaves file)

If [- n "$HADOOP_SECURE_DN_USER"]; then

Echo\

"Attempting to stop secure cluster, skipping datanodes."\

"Run stop-secure-dns.sh as root to complete shutdown."

Else

"$HADOOP_PREFIX/sbin/hadoop-daemons.sh"\

-config "$HADOOP_CONF_DIR"\

Script "$bin/hdfs" stop datanode

Fi

#

# go to view the hadoop-daemons.sh script

[hadoop@hadoop001 sbin] $cat hadoop-daemon.sh | grep pid

# HADOOP_PID_DIR The pid files are stored. / tmp by default.

Pid=$HADOOP_PID_DIR/hadoop-$HADOOP_IDENT_STRING-$command.pid

If [- f $pid]; then

If kill-0 `cat $pid` > / dev/null 2 > & 1; then

Echo $command running as process `cat $pid`. Stop it first.

Echo $! > $pid

If [- f $pid]; then

TARGET_PID= `cat $pid`

Rm-f $pid

Thank you for reading this article carefully. I hope the article "sample Analysis of PID in HDFS" shared by the editor will be helpful to you. At the same time, I also hope you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!