WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin

运行 HDFS 命令，总是出现恼人的

 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Found 2 items

# hdfs dfs -ls /
23/02/24 16:00:53 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Found 2 items
drwxr-xr-x   - yunwei supergroup          0 2023-02-24 14:39 /hbase
drwxr-xr-x   - yunwei supergroup          0 2023-02-24 14:55 /usr

这个警告是说，Hadoop 没有成功加载你电脑的本地库，所以使用了内置的 Java 类库。

本地库的作用：提升一些操作的性能（Java 不够快），并且弥补 Java 类库的不足，Hadoop 为某些组件提供了自己的本地实现，保存在一个独立的动态链接的库里，在 类 Uinux 平台上名为 libhadoop.so。

1.首先进入目录查看

# ll /data/apps/hadoop/lib/native/
total 5360
-rw-rw-r-- 1 yunwei yunwei 1370614 Oct  3  2016 libhadoop.a
-rw-rw-r-- 1 yunwei yunwei 1934326 Oct  3  2016 libhadooppipes.a
lrwxrwxrwx 1 yunwei yunwei      18 Oct  3  2016 libhadoop.so -> libhadoop.so.1.0.0
-rwxrwxr-x 1 yunwei yunwei  798496 Oct  3  2016 libhadoop.so.1.0.0
-rw-rw-r-- 1 yunwei yunwei  650580 Oct  3  2016 libhadooputils.a
-rw-rw-r-- 1 yunwei yunwei  443766 Oct  3  2016 libhdfs.a
lrwxrwxrwx 1 yunwei yunwei      16 Oct  3  2016 libhdfs.so -> libhdfs.so.0.0.0
-rwxrwxr-x 1 yunwei yunwei  280368 Oct  3  2016 libhdfs.so.0.0.0

目录下确实没有这个文件，到hadoop的目录下

# grep -R 'java.library.path' *
bin/yarn:  YARN_OPTS="$YARN_OPTS -Djava.library.path=$JAVA_LIBRARY_PATH"
bin/yarn.cmd:    set YARN_OPTS=%YARN_OPTS% -Djava.library.path=%JAVA_LIBRARY_PATH%
etc/hadoop/yarn-env.cmd:  set YARN_OPTS=%YARN_OPTS% -Djava.library.path=%JAVA_LIBRARY_PATH%
etc/hadoop/yarn-env.sh:  YARN_OPTS="$YARN_OPTS -Djava.library.path=$JAVA_LIBRARY_PATH"
libexec/hadoop-config.sh:# setup 'java.library.path' for native-hadoop code if necessary
libexec/hadoop-config.sh:  HADOOP_OPTS="$HADOOP_OPTS -Djava.library.path=$JAVA_LIBRARY_PATH"
libexec/hadoop-config.cmd:@rem setup 'java.library.path' for native hadoop code if necessary
libexec/hadoop-config.cmd:  set HADOOP_OPTS=%HADOOP_OPTS% -Djava.library.path=%JAVA_LIBRARY_PATH%
share/doc/hadoop/mapreduce/CHANGES.txt:    MAPREDUCE-4458. Warn if java.library.path is used for AM or Task
share/doc/hadoop/mapreduce/CHANGES.txt:    MAPREDUCE-4072. User set java.library.path seems to overwrite default
share/doc/hadoop/mapreduce/CHANGES.txt:    MAPREDUCE-3259. Added java.library.path of NodeManager to

果然发现有定义这个参数，到哪没有具体指定，除了在配置文件中指定外，在主机的~/.bash_profile指定参数也是一样的。

# vi ~/.bash_profile
 
 
export JAVA_LIBRARY_PATH=/data/apps/hadoop/lib/native
 
# source ~/.bash_profile

 到此，执行hadoop的命令已无警告