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https://issues.apache.org/jira/browse/HBASE-9582?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13779824#comment-13779824
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Igor Vikhrov commented on HBASE-9582:
-------------------------------------
Also I've noticed that problem is solved by setting "setCaching" to less value
(for example,2). In this case same Scans give same results.
> 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: Igor Vikhrov
>
> 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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