Hello J.G, Thank you for your reply. My hbase version is the newest : 0.20.0.
I have two tables, both having 10000 cells, one having 100 rows and 100 columns per row, another having 10000 rows and 1 column per row. I wanted to test the speed scanning all the cells in 2 tables. When I scanned this 2 tables, at "scanner = table.getScanner(s);", the same exceptions in last mail were both thrown . And following is the complete codes: public class HbaseScannerTest { // private final String TableNameA = "ttest1"; // private final String TableNameB = "ttest2"; private final String ColumnFamily = "cf_test"; private final String Column = "c_test"; private void scan(String tableName) { HBaseConfiguration config = new HBaseConfiguration(); HTable table = null; ResultScanner scanner = null; try { table = new HTable(config, tableName); Scan s = new Scan(); s = s.addFamily(Bytes.toBytes(ColumnFamily)); scanner = table.getScanner(s); for (Result rr = scanner.next(); rr != null; rr = scanner.next()) { NavigableMap<byte[], byte[]> map = rr.getFamilyMap(Bytes.toBytes(ColumnFamily)); Set<byte[]> set = map.keySet(); Iterator<byte[]> iter = set.iterator(); while(iter.hasNext()){ byte[] key = iter.next(); String strKey = Bytes.toString(key); String strValue = Bytes.toString(map.get(key)); System.out.println("key:" + strKey + ", value:" + strValue); } } } catch(Exception e){ e.printStackTrace(); } finally { try{ if(scanner != null){ scanner.close(); } if(table != null){ table.close(); } }catch(Exception e){ e.printStackTrace(); } } } public static void main(String[] args) { if(args == null || args.length == 0){ System.out.println("param error."); return; }else{ HbaseScannerTest scannerTest = new HbaseScannerTest(); long t1 = System.currentTimeMillis(); scannerTest.scan(args[0]); long t2 = System.currentTimeMillis(); System.out.println("*********scan " + args[0] + " need : " + (t2 - t1)); } } } When the exceptions were thrown, the log in master was normal, and the logs in other region servers were normal too, but in /192.168.33.6:60020(sometimes another server) which pointed in the exceptions, the log is abnormal. I think I have put all the relational logs in last mail, because the remained logs looks like unrelated at all. The following is the more complete logs: 2009-09-18 11:08:37,050 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_CLOSE: TestTable,0002215349,1251708925379: Overloaded 2009-09-18 11:08:37,051 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_CLOSE: TestTable,0001302275,1251708861978: Overloaded 2009-09-18 11:08:37,051 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_CLOSE: TestTable,0000884288,1251705503037: Overloaded 2009-09-18 11:08:37,051 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_CLOSE: TestTable,0000065336,1251705454231: Overloaded 2009-09-18 11:08:37,051 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_CLOSE: TestTable,0001062941,1251708879165: Overloaded 2009-09-18 11:08:37,051 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_CLOSE: TestTable,0002215349,1251708925379: Overloaded 2009-09-18 11:08:37,052 INFO org.apache.hadoop.hbase.regionserver.HRegion: Closed TestTable,0002215349,1251708925379 2009-09-18 11:08:37,052 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_CLOSE: TestTable,0001302275,1251708861978: Overloaded 2009-09-18 11:08:37,052 INFO org.apache.hadoop.hbase.regionserver.HRegion: Closed TestTable,0001302275,1251708861978 2009-09-18 11:08:37,053 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_CLOSE: TestTable,0000884288,1251705503037: Overloaded 2009-09-18 11:08:37,053 INFO org.apache.hadoop.hbase.regionserver.HRegion: Closed TestTable,0000884288,1251705503037 2009-09-18 11:08:37,053 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_CLOSE: TestTable,0000065336,1251705454231: Overloaded 2009-09-18 11:08:37,053 INFO org.apache.hadoop.hbase.regionserver.HRegion: Closed TestTable,0000065336,1251705454231 2009-09-18 11:08:37,053 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_CLOSE: TestTable,0001062941,1251708879165: Overloaded 2009-09-18 11:08:37,054 INFO org.apache.hadoop.hbase.regionserver.HRegion: Closed TestTable,0001062941,1251708879165 2009-09-18 11:08:49,109 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_OPEN: TestTable,0000952473,1251709074516 2009-09-18 11:08:49,109 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_OPEN: TestTable,0000595460,1251708629215 2009-09-18 11:08:49,109 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_OPEN: webpage,http:\x2F\x2Fnews.163.com \x2F09\x2F0803\x2F01\x2F5FOO155J0001124J.html1251254047232_16208,1251254433708 2009-09-18 11:08:49,109 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: MSG_REGION_OPEN: TestTable,0002805208,1251709024537 2009-09-18 11:08:49,109 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_OPEN: TestTable,0000952473,1251709074516 2009-09-18 11:08:49,148 INFO org.apache.hadoop.hbase.regionserver.HRegion: region TestTable,0000952473,1251709074516/1184073320 available; sequence id is 5922826 2009-09-18 11:08:49,148 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_OPEN: TestTable,0000595460,1251708629215 2009-09-18 11:08:49,191 INFO org.apache.hadoop.hbase.regionserver.HRegion: region TestTable,0000595460,1251708629215/1982730697 available; sequence id is 5937085 2009-09-18 11:08:49,191 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_OPEN: webpage,http:\x2F\x2Fnews.163.com \x2F09\x2F0803\x2F01\x2F5FOO155J0001124J.html1251254047232_16208,1251254433708 2009-09-18 11:08:49,285 INFO org.apache.hadoop.hbase.regionserver.HRegion: region webpage,http:\x2F\x2Fnews.163.com\x2F09\x2F0803\x2F01\x2F5FOO155J0001124J.html1251254047232_16208,1251254433708/174964099 available; sequence id is 173787 2009-09-18 11:08:49,285 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Worker: MSG_REGION_OPEN: TestTable,0002805208,1251709024537 2009-09-18 11:08:49,355 INFO org.apache.hadoop.hbase.regionserver.HRegion: region TestTable,0002805208,1251709024537/1263036978 available; sequence id is 5922825 2009-09-18 11:18:04,909 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: compactions no longer limited 2009-09-18 11:32:03,523 ERROR org.apache.hadoop.hbase.regionserver.HRegionServer: org.apache.hadoop.hbase.UnknownScannerException: Name: -1 at org.apache.hadoop.hbase.regionserver.HRegionServer.next(HRegionServer.java:1905) at sun.reflect.GeneratedMethodAccessor3.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.HBaseRPC$Server.call(HBaseRPC.java:650) at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:913) 2009-09-18 11:32:03,529 INFO org.apache.hadoop.ipc.HBaseServer: IPC Server handler 1 on 60020, call next(-1, 1) from 192.168.33.7:43810: error: org.apache.hadoop.hbase.UnknownScannerException: Name: -1 org.apache.hadoop.hbase.UnknownScannerException: Name: -1 at org.apache.hadoop.hbase.regionserver.HRegionServer.next(HRegionServer.java:1905) at sun.reflect.GeneratedMethodAccessor3.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.HBaseRPC$Server.call(HBaseRPC.java:650) at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:913) Any suggestion? LvZheng