HBase源码分析之HRegion上MemStore的flsuh流程(二) 继上篇《HBase源码分析之HRegion上MemStore的flsuh流程(一)》之后,我们继续分析下HRegion上MemStore flush的核心方法internalFlushcache(),它的主要流程如图所示: 其中,internalFlushcache()方法的代码如下: /** * Flush the memstore. Flushing the memstore is a little tricky. We have a lot of updates in the * memstore, all of which have also been written to the wal. We need to write those updates in the * memstore out to disk, while being able to process reads/writes as much as possible during the * flush operation. * <p>This method may block for som...
Hadoop常见错误1 1 关于 Warning: $HADOOP_HOME is deprecated. hadoop 1.0.0版本,安装完之后敲入hadoop命令时,老是提示这个警告: Warning: $HADOOP_HOME is deprecated. 经查hadoop-1.0.0/bin/hadoop脚本和"hadoop-config.sh"脚本,发现脚本中对HADOOP_HOME的环境变量设置做了判断,笔者的环境根本不需要设置HADOOP_HOME环境变量。 解决方案一:编辑"/etc/profile"文件,去掉HADOOP_HOME的变量设定,重新输入hadoop fs命令,警告消失。 解决方案二:编辑"/etc/profile"文件,添加一个环境变量,之后警告消失: export HADOOP_HOME_WARN_SUPPRESS=1 我们这里本着不动Hadoop原配置文件的前提下,采用"方案二",在"/etc/profile"文件添加上面内容,并用命令"source /etc/profile"使之有效。 2 解决"no datanode to stop"问题 当我停止Hadoop时发...