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From "Enis Soztutar (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-14501) NPE in replication with TDE
Date Wed, 30 Sep 2015 00:01:18 GMT

     [ https://issues.apache.org/jira/browse/HBASE-14501?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Enis Soztutar updated HBASE-14501:
----------------------------------
    Attachment: hbase-14501_v1.patch

Let's try this patch. BaseDecoder uses a PushbackIS to read the first byte to decide whether
this is a legit EOF or not. If legit, returns false, otherwise lets the actual Decoder do
{{parseCell()}}. If parseCell throws an EOF, it is a partial cell read and gets re-thrown.


I'll test this with the TDE setup to see whether we still see a NPE. Probably, it won't be
possible to bring up a mini hdfs cluster with TDE setup.  

> NPE in replication with TDE
> ---------------------------
>
>                 Key: HBASE-14501
>                 URL: https://issues.apache.org/jira/browse/HBASE-14501
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Enis Soztutar
>         Attachments: hbase-14501_v1.patch
>
>
> We are seeing a NPE when replication (or in this case async wal replay for region replicas)
is run on top of an HDFS cluster with TDE configured.
> This is the stack trace:
> {code}
> java.lang.NullPointerException
>         at org.apache.hadoop.hbase.CellUtil.matchingRow(CellUtil.java:370)
>         at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource.countDistinctRowKeys(ReplicationSource.java:649)
>         at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource.readAllEntriesToReplicateOrNextFile(ReplicationSource.java:450)
>         at org.apache.hadoop.hbase.replication.regionserver.ReplicationSource.run(ReplicationSource.java:346)
> {code}
> This stack trace can only happen if WALEdit.getCells() returns an array containing null
entries. I believe this happens due to {{KeyValueCodec.parseCell()}} uses {{KeyValueUtil.iscreate()}}
which returns null in case of EOF at the beginning. However, the contract for the Decoder.parseCell()
is not clear whether returning null is acceptable or not. The other Decoders (CompressedKvDecoder,
CellCodec, etc) do not return null while KeyValueCodec does. 
> BaseDecoder has this code: 
> {code}
>   public boolean advance() throws IOException {
>     if (!this.hasNext) return this.hasNext;
>     if (this.in.available() == 0) {
>       this.hasNext = false;
>       return this.hasNext;
>     }
>     try {
>       this.current = parseCell();
>     } catch (IOException ioEx) {
>       rethrowEofException(ioEx);
>     }
>     return this.hasNext;
>   }
> {code}
> which is not correct since it uses {{IS.available()}} not according to the javadoc: (https://docs.oracle.com/javase/7/docs/api/java/io/InputStream.html#available()).
DFSInputStream implements {{available()}} as the remaining bytes to read from the stream,
so we do not see the issue there. {{CryptoInputStream.available()}} does a similar thing but
see the issue. 
> So two questions: 
>  - What should be the interface for Decoder.parseCell()? Can it return null? 
>  - How to properly fix  BaseDecoder.advance() to not rely on {{available()}} call. 



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