[jira] Commented: (HBASE-2506) Too easy to OOME a RS

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

    [ https://issues.apache.org/jira/browse/HBASE-2506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12862867#action_12862867 ] 

Jean-Daniel Cryans commented on HBASE-2506:
-------------------------------------------

Well it seems that for scans we already have everything in place:
{code}
  /**
   * Maximum number of bytes returned when calling a scanner's next method.
   * Note that when a single row is larger than this limit the row is still
   * returned completely.
   * 
   * The default value is unlimited.
   */
  public static long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = Long.MAX_VALUE;
{code}
Instead of keeping it to that default, we could just set it to a reasonable value like 64MB.

> Too easy to OOME a RS
> ---------------------
>
>                 Key: HBASE-2506
>                 URL: https://issues.apache.org/jira/browse/HBASE-2506
>             Project: Hadoop HBase
>          Issue Type: Bug
>            Reporter: Jean-Daniel Cryans
>             Fix For: 0.20.5, 0.21.0
>
>
> Testing a cluster with 1GB heap, I found that we are letting the region servers kill themselves too easily when scanning using pre-fetching. To reproduce, get 10-20M rows using PE and run a count in the shell using CACHE => 30000 or any other very high number. For good measure, here's the stack trace:
> {code}
> 2010-04-30 13:20:23,241 FATAL org.apache.hadoop.hbase.regionserver.HRegionServer: OutOfMemoryError, aborting.
> java.lang.OutOfMemoryError: Java heap space
>         at java.util.Arrays.copyOf(Arrays.java:2786)
>         at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:94)
>         at java.io.DataOutputStream.write(DataOutputStream.java:90)
>         at org.apache.hadoop.hbase.client.Result.writeArray(Result.java:478)
>         at org.apache.hadoop.hbase.io.HbaseObjectWritable.writeObject(HbaseObjectWritable.java:312)
>         at org.apache.hadoop.hbase.io.HbaseObjectWritable.write(HbaseObjectWritable.java:229)
>         at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:941)
> 2010-04-30 13:20:23,241 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Dump of metrics: request=0.0, regions=29, stores=29, storefiles=44, storefileIndexSize=6, memstoreSize=255,
>  compactionQueueSize=0, usedHeap=926, maxHeap=987, blockCacheSize=1700064, blockCacheFree=205393696, blockCacheCount=0, blockCacheHitRatio=0
> {code}
> I guess the same could happen with largish write buffers. We need something better than OOME.

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