[jira] Updated: (HBASE-2909) SoftValueSortedMap is broken, can generate NPEs

["Jean-Daniel Cryans (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-2909?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jean-Daniel Cryans updated HBASE-2909:
--------------------------------------

    Attachment: hbase-2909.patch

Here's a more "normal" way of doing a soft references structure, with the SoftValue now inside SoftValueSortedMap. I also got rid of the implementation of Map.Entry (which was suspicious) and disabled entrySet because 1) it wasn't used and 2) it used the Map.Entry which wasn't really one. Ran a few tests and it works, need more at-scale testing.

> SoftValueSortedMap is broken, can generate NPEs
> -----------------------------------------------
>
>                 Key: HBASE-2909
>                 URL: https://issues.apache.org/jira/browse/HBASE-2909
>             Project: HBase
>          Issue Type: Bug
>          Components: client
>    Affects Versions: 0.20.6, 0.89.20100621
>            Reporter: Jean-Daniel Cryans
>            Priority: Blocker
>             Fix For: 0.20.7, 0.90.0
>
>         Attachments: hbase-2909.patch
>
>
> The way SoftValueSortedMap is using SoftValues, it looks like that it's able to get it's keys garbage collected along with the values themselves. We got this issue in production but I was also able to randomly generate it using YCSB with 300 threads. Here's an example on 0.20 with jdk 1.6u14:
> {noformat}
> java.lang.NullPointerException
>         at org.apache.hadoop.hbase.util.Bytes.compareTo(Bytes.java:1036)
>         at org.apache.hadoop.hbase.util.Bytes$ByteArrayComparator.compare(Bytes.java:104)
>         at org.apache.hadoop.hbase.util.Bytes$ByteArrayComparator.compare(Bytes.java:96)
>         at java.util.TreeMap.cmp(TreeMap.java:1911)
>         at java.util.TreeMap.get(TreeMap.java:1835)
>         at org.apache.hadoop.hbase.util.SoftValueSortedMap.get(SoftValueSortedMap.java:91)
>         at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.getCachedLocation(HConnectionManager.java:788)
>         at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegionInMeta(HConnectionManager.java:651)
>         at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegion(HConnectionManager.java:634)
>         at org.apache.hadoop.hbase.client.HConnectionManager$TableServers.locateRegion(HConnectionManager.java:601)
>         at org.apache.hadoop.hbase.client.HTable.<init>(HTable.java:128)
>         at org.apache.hadoop.hbase.thrift.ThriftServer$HBaseHandler.getTable(ThriftServer.java:262)
>         at org.apache.hadoop.hbase.thrift.ThriftServer$HBaseHandler.mutateRowTs(ThriftServer.java:585)
>         at org.apache.hadoop.hbase.thrift.ThriftServer$HBaseHandler.mutateRow(ThriftServer.java:578)
>         at org.apache.hadoop.hbase.thrift.generated.Hbase$Processor$mutateRow.process(Hbase.java:2345)
>         at org.apache.hadoop.hbase.thrift.generated.Hbase$Processor.process(Hbase.java:1988)
>         at org.apache.thrift.server.TThreadPoolServer$WorkerProcess.run(TThreadPoolServer.java:259)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
>         at java.lang.Thread.run(Thread.java:619)
> {noformat}
> In this specific case, the null cannot be the passed key because it's coming from HTable which uses HConstants.EMPTY_START_ROW. It cannot be a null key that was inserted previously because we would have got the NPE at insert time. This can only mean that some key *became* null.

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