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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13329) ArrayIndexOutOfBoundsException in CellComparator#getMinimumMidpointArray
Date Mon, 15 Jun 2015 04:58:01 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14585430#comment-14585430

Lars Hofhansl commented on HBASE-13329:

Hmmm... We compare against {{minLength}}, which is a short, so we cannot grow beyond the short
range (and if the data is corrupted and minLenth itself overflew, than - since diffIdx starts
at 0 - we'd overflow immediately.
I also agree that this compares bytes in the row key itself (not keys).

Here's the scenario that can go wrong... Later in the code we do this:
if (diffIdx >= minLength) {
         // leftKey's row is prefix of rightKey's.
         newRowKey = new byte[diffIdx + 1];
         System.arraycopy(rightKey, ROW_LENGTH_SIZE, newRowKey, 0, diffIdx + 1);
       } else {
So what if minLength was exactly Short.MAX_VALUE? In that case {{diffIdx}} can overflow (and
we'd get the negative array size exception). But note that in that case it is _not_ OK to
have it grow by one, as we'd create a rowkey array > Short.MAX_VALUE. It seems in that
case we'd have to not do the getShortMidpointKey optimization...?

It seems to me that can only happen when the keys are identical _and_ of size Short.MAX_VALUE.
In case we can either take the left or the right key, right? There _is_ no mid key in that

> ArrayIndexOutOfBoundsException in CellComparator#getMinimumMidpointArray
> ------------------------------------------------------------------------
>                 Key: HBASE-13329
>                 URL: https://issues.apache.org/jira/browse/HBASE-13329
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>    Affects Versions: 1.0.1
>         Environment: linux-debian-jessie
> ec2 - t2.micro instances
>            Reporter: Ruben Aguiar
>            Assignee: Ruben Aguiar
>            Priority: Critical
>             Fix For: 2.0.0, 1.0.2, 1.2.0, 1.1.1
>         Attachments: 13329-asserts.patch, 13329-v1.patch
> While trying to benchmark my opentsdb cluster, I've created a script that sends to hbase
always the same value (in this case 1). After a few minutes, the whole region server crashes
and the region itself becomes impossible to open again (cannot assign or unassign). After
some investigation, what I saw on the logs is that when a Memstore flush is called on a large
region (128mb) the process errors, killing the regionserver. On restart, replaying the edits
generates the same error, making the region unavailable. Tried to manually unassign, assign
or close_region. That didn't work because the code that reads/replays it crashes.
> From my investigation this seems to be an overflow issue. The logs show that the function
getMinimumMidpointArray tried to access index -32743 of an array, extremely close to the minimum
short value in Java. Upon investigation of the source code, it seems an index short is used,
being incremented as long as the two vectors are the same, probably making it overflow on
large vectors with equal data. Changing it to int should solve the problem.
> Here follows the hadoop logs of when the regionserver went down. Any help is appreciated.
Any other information you need please do tell me:
> 2015-03-24 18:00:56,187 INFO  [regionserver//] wal.FSHLog: Rolled
WAL /hbase/WALs/,16020,1427216382590/
with entries=143, filesize=134.70 MB; new WAL /hbase/WALs/,16020,1427216382590/
> 2015-03-24 18:00:56,188 INFO  [regionserver//] wal.FSHLog: Archiving
to hdfs://
> 2015-03-24 18:04:35,722 INFO  [MemStoreFlusher.0] regionserver.HRegion: Started memstore
flush for tsdb,,1427133969325.52bc1994da0fea97563a4a656a58bec2., current region memstore size
128.04 MB
> 2015-03-24 18:04:36,154 FATAL [MemStoreFlusher.0] regionserver.HRegionServer: ABORTING
region server,16020,1427216382590: Replay of WAL required. Forcing server shutdown
> org.apache.hadoop.hbase.DroppedSnapshotException: region: tsdb,,1427133969325.52bc1994da0fea97563a4a656a58bec2.
> 	at org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:1999)
> 	at org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:1770)
> 	at org.apache.hadoop.hbase.regionserver.HRegion.flushcache(HRegion.java:1702)
> 	at org.apache.hadoop.hbase.regionserver.MemStoreFlusher.flushRegion(MemStoreFlusher.java:445)
> 	at org.apache.hadoop.hbase.regionserver.MemStoreFlusher.flushRegion(MemStoreFlusher.java:407)
> 	at org.apache.hadoop.hbase.regionserver.MemStoreFlusher.access$800(MemStoreFlusher.java:69)
> 	at org.apache.hadoop.hbase.regionserver.MemStoreFlusher$FlushHandler.run(MemStoreFlusher.java:225)
> 	at java.lang.Thread.run(Thread.java:745)
> Caused by: java.lang.ArrayIndexOutOfBoundsException: -32743
> 	at org.apache.hadoop.hbase.CellComparator.getMinimumMidpointArray(CellComparator.java:478)
> 	at org.apache.hadoop.hbase.CellComparator.getMidpoint(CellComparator.java:448)
> 	at org.apache.hadoop.hbase.io.hfile.HFileWriterV2.finishBlock(HFileWriterV2.java:165)
> 	at org.apache.hadoop.hbase.io.hfile.HFileWriterV2.checkBlockBoundary(HFileWriterV2.java:146)
> 	at org.apache.hadoop.hbase.io.hfile.HFileWriterV2.append(HFileWriterV2.java:263)
> 	at org.apache.hadoop.hbase.io.hfile.HFileWriterV3.append(HFileWriterV3.java:87)
> 	at org.apache.hadoop.hbase.regionserver.StoreFile$Writer.append(StoreFile.java:932)
> 	at org.apache.hadoop.hbase.regionserver.StoreFlusher.performFlush(StoreFlusher.java:121)
> 	at org.apache.hadoop.hbase.regionserver.DefaultStoreFlusher.flushSnapshot(DefaultStoreFlusher.java:71)
> 	at org.apache.hadoop.hbase.regionserver.HStore.flushCache(HStore.java:879)
> 	at org.apache.hadoop.hbase.regionserver.HStore$StoreFlusherImpl.flushCache(HStore.java:2128)
> 	at org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:1953)
> 	... 7 more
> 2015-03-24 18:04:36,156 FATAL [MemStoreFlusher.0] regionserver.HRegionServer: RegionServer
abort: loaded coprocessors are: [org.apache.hadoop.hbase.coprocessor.MultiRowMutationEndpoint]

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