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From "Uma Maheswara Rao G (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-1599) Umbrella Jira for Improving HBASE support in HDFS
Date Sat, 31 Mar 2012 10:16:32 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1599?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13243105#comment-13243105
] 

Uma Maheswara Rao G commented on HDFS-1599:
-------------------------------------------

@Nicholas,

 Currently I can see below points, where Hbase is invoking the HDFS APIs.

1) Accessing the Cache class from FileSystem
      {code}
         field.setAccessible(true);
         Field cacheField = FileSystem.class.getDeclaredField("CACHE");
         cacheField.setAccessible(true);
         Object cacheInstance = cacheField.get(fs);
         hdfsClientFinalizer = (Thread)field.get(cacheInstance)
      {code}

2) Invoking the getJar method from JarFinder
    {code}
      Class<?> jarFinder = Class.forName("org.apache.hadoop.util.JarFinder");
      // hadoop-0.23 has a JarFinder class that will create the jar
      // if it doesn't exist.  Note that this is needed to run the mapreduce
      // unit tests post-0.23, because mapreduce v2 requires the relevant jars
      // to be in the mr cluster to do output, split, etc.  At unit test time,
      // the hbase jars do not exist, so we need to create some.  Note that we
      // can safely fall back to findContainingJars for pre-0.23 mapreduce.
      Method m = jarFinder.getMethod("getJar", Class.class);
    {code}

3) accessing the getNumCurrentReplicas from DFSOutPutStream
4) accessing the creatWriter method from SequenceFile.Writer
5) accessing the syncFS method from SequenceFile writer
6) hflush apis
7) accessing the 'out' variable from FSDataOutPutStream
8) recoverLease api from DistributedFilesystem
9) using org.apache.hadoop.hdfs.protocol.FSConstants.SafeModeAction.SAFEMODE_GET
   Hbase currently broken with 23 version because of this constant usage.


                
> Umbrella Jira for Improving HBASE support in HDFS
> -------------------------------------------------
>
>                 Key: HDFS-1599
>                 URL: https://issues.apache.org/jira/browse/HDFS-1599
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Sanjay Radia
>
> Umbrella Jira for improved HBase support in HDFS

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