hbase源码阅读－start flow

奥尔覅几22

　　today i will learn to hit the hbase source codes.
　　for  the rule from simple to difficult,i will get a standalone mode to run hbase to do this.
　　ok,let's look at the shell
　　  start-hbase.sh

　　it will start certain daemons ,e.g., HMaster,HResionServer,Zookeeper(if any) etc.details listed below:

if [ "$distMode" == 'false' ]
then
"$bin"/hbase-daemon.sh start master
else
"$bin"/hbase-daemons.sh --config "${HBASE_CONF_DIR}" start zookeeper
"$bin"/hbase-daemon.sh --config "${HBASE_CONF_DIR}" start master
"$bin"/hbase-daemons.sh --config "${HBASE_CONF_DIR}" \
--hosts "${HBASE_REGIONSERVERS}" start regionserver
"$bin"/hbase-daemons.sh --config "${HBASE_CONF_DIR}" \
--hosts "${HBASE_BACKUP_MASTERS}" start master-backup
fi
 　　yes,the relase of hbase list one more daemon named "maser-backup" then hbase-0.20.6,but now i dont care it as i will consume it  when need.
　　---
　　今天启动0.94启动不了,发现异常:
　　Exception in thread "main" java.lang.NoClassDefFoundError: hadoop,class:org/apache/hadoop/hbase/util/GetJavaProperty,params:java/library/path
　　刚开始以为是导入到eclipse引起的,但后来想想只是导入没有做其它修改应该不是这个原因.
　　由于对shell不熟,经过:docs阅读 -> goolge 后发现没相关问题,再阅读源码,调度.最終定位到bin/hbase文件:
　　for 0.94

HADOOP_IN_PATH=$(PATH="${HADOOP_HOME:-${HADOOP_PREFIX}}/bin:$PATH" which hadoop 2>/dev/null)
#echo "xx $HADOOP_IN_PATH"  
if [ -f ${HADOOP_IN_PATH} ]; then
HADOOP_JAVA_LIBRARY_PATH=$(HADOOP_CLASSPATH="$CLASSPATH" ${HADOOP_IN_PATH} \
org.apache.hadoop.hbase.util.GetJavaProperty java.library.path 2>/dev/null)
if [ -n "$HADOOP_JAVA_LIBRARY_PATH" ]; then
JAVA_LIBRARY_PATH=$(append_path "${JAVA_LIBRARY_PATH}" "$HADOOP_JAVA_LIBRARY_PATH")
fi
CLASSPATH=$(append_path "${CLASSPATH}" `${HADOOP_IN_PATH} classpath 2>/dev/null`)
fi

 　　but 0.92:

#If avail, add Hadoop to the CLASSPATH and to the JAVA_LIBRARY_PATH
if [ ! -z $HADOOP_HOME ]; then
HADOOPCPPATH=""
if [ -z $HADOOP_CONF_DIR ]; then
HADOOPCPPATH=$(append_path "${HADOOPCPPATH}" "${HADOOP_HOME}/conf")
else
HADOOPCPPATH=$(append_path "${HADOOPCPPATH}" "${HADOOP_CONF_DIR}")
fi
if [ "`echo ${HADOOP_HOME}/hadoop-core*.jar`" != "${HADOOP_HOME}/hadoop-core*.jar" ] ; then
HADOOPCPPATH=$(append_path "${HADOOPCPPATH}" `ls ${HADOOP_HOME}/hadoop-core*.jar | head -1`)
else
HADOOPCPPATH=$(append_path "${HADOOPCPPATH}" `ls ${HADOOP_HOME}/hadoop-common*.jar | head -1`)
HADOOPCPPATH=$(append_path "${HADOOPCPPATH}" `ls ${HADOOP_HOME}/hadoop-hdfs*.jar | head -1`)
HADOOPCPPATH=$(append_path "${HADOOPCPPATH}" `ls ${HADOOP_HOME}/hadoop-mapred*.jar | head -1`)
fi
for i in "${HADOOP_HOME}/lib/"*.jar; do
HADOOPCPPATH="${HADOOPCPPATH}:$i"
done
CLASSPATH=$(append_path "${CLASSPATH}" "${HADOOPCPPATH}")
if [ -d "${HADOOP_HOME}/lib/native" ]; then
JAVA_PLATFORM=`CLASSPATH=${HADOOPCPPATH} ${JAVA} org.apache.hadoop.util.PlatformName | sed -e "s/ /_/g"`
if [ -d "${HADOOP_HOME}/lib/native/${JAVA_PLATFORM}" ]; then
JAVA_LIBRARY_PATH=$(append_path "${JAVA_LIBRARY_PATH}" "${HADOOP_HOME}/lib/native/${JAVA_PLATFORM}")
fi
fi
fi

 　　其实区别就是在这里,可能是这版本不再考虑HADOOP_HOME所以完全没有再利用它来处理.
　　而在xx处输出是:/path/to/hadoop/bin/hadoop,再结合异常,断定了在添加hadoop到classpath时直接利用hadoop(shell)执行了GetJavaProperty(forjava.lib.path)引起的异常,当然这是可选的.所以当我把HADOP_IN_PATH comment后便正常操作了.
　　经证实,是因为hadoop与hbase安装在同一台机器上引起的,因为hbase从$PATH中读取了hadoop (shell),于是乎使用hadoop相关jars来运行.