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Date: Thu, 19 Sep 2013 10:29:51 +0000 (UTC)
From: "Vikhrov Igor (JIRA)" <jira@apache.org>
To: dev@hbase.apache.org
Message-ID: <JIRA.12669430.1379586568108.161348.1379586591765@arcas>
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References: <JIRA.12669430.1379586568108@arcas>
Subject: [jira] [Created] (HBASE-9582) MapReduce Scan gives different output
 every times
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Vikhrov Igor created HBASE-9582:
-----------------------------------

             Summary: MapReduce Scan gives different output every times
                 Key: HBASE-9582
                 URL: https://issues.apache.org/jira/browse/HBASE-9582
             Project: HBase
          Issue Type: Bug
    Affects Versions: 0.94.5
         Environment: hadoop 1.0.3
            Reporter: Vikhrov Igor


I have this Scan


Scan scan = new Scan();
scan.setCaching(50);
scan.setCacheBlocks(false);
scan.setMaxVersions();
scan.setTimeRange(Long.valueOf(args[7] + "000"),Long.valueOf(args[8] + "000"));
SingleColumnValueFilter filter = new SingleColumnValueFilter(Bytes.toBytes(args[1]),Bytes.toBytes(args[2]),CompareFilter.CompareOp.EQUAL,new BinaryComparator(Bytes.toBytes(args[3])));
filter.setFilterIfMissing(true);
scan.setFilter(filter);


It works without any warns and errors in command line. But when regionservers CPU is high loaded, Scan with the same parameters (Column, value, timestamps) gives different results. For example
first time - Map output records=571374   
second time -  Map output records=777620
third time - Map output records=776099

Regionservers log includes such WARNs:

2013-09-19 13:29:44,827 WARN org.apache.hadoop.ipc.HBaseServer: (responseTooSlow): {"processingtimems":30759,"call":"next(-308003858163246780, 10), rpc version=1, client version=29, methodsFingerPrint=-1368823753","client":"10.10.54.22:53361","starttimems":1379582954067,"queuetimems":1,"class":"HRegionServer","responsesize":51343,"method":"next"}

and these ERRORs:
2013-09-19 13:26:18,202 ERROR org.apache.hadoop.hbase.regionserver.HRegionServer: 
org.apache.hadoop.hbase.ipc.CallerDisconnectedException: Aborting call next(-9095740742796333934, 10), rpc version=1, client version=29, methodsFingerPrint=-1368823753 from 10.10.54.22:32914 after 60059 ms, since caller disconnected                                                                                  
        at org.apache.hadoop.hbase.ipc.HBaseServer$Call.throwExceptionIfCallerDisconnected(HBaseServer.java:436)                                             
        at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextInternal(HRegion.java:3723)                                                    
        at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextRaw(HRegion.java:3643)                                                         
        at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextRaw(HRegion.java:3635)                                                         
        at org.apache.hadoop.hbase.regionserver.HRegionServer.next(HRegionServer.java:2483)                                                                  
        at sun.reflect.GeneratedMethodAccessor24.invoke(Unknown Source)                                                                                      
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)                                                             
        at java.lang.reflect.Method.invoke(Method.java:597)                                                                                                  
        at org.apache.hadoop.hbase.ipc.WritableRpcEngine$Server.call(WritableRpcEngine.java:320)                                                             
        at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:1426)


When regionservers CPU is not loaded, Scan gives same results every times.
In this case regionservers log doesn't include any WARNs.

Why does it happen? I want to be sure that Scan give me all the data that I request no matter how CPU is using now.


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