Major Description
In many failed map tasks we see things like this:
INFO org.apache.hadoop.ipc.Server: IPC Server handler 2 on 64020, call next(-8330618580557781998) from 192.168.1.84:59678: error: org.apache.hadoop.hbase.UnknownScannerException: Name: -8330618580557781998
Here is an excerpt of the regionserver log:
2008-08-08 10:49:13,276 INFO org.apache.hadoop.hbase.regionserver.HRegion: Starting split of region entities,North_America-United_States-Missouri-Oran-b9c7e44a-4a2b-11dd-abd4-1231390079f2,1218205066272 2008-08-08 10:49:13,310 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: Compactions and cache flushes disabled for region entities,North_America-United_States-Missouri-Oran-b9c7e44a-4a2b-11dd-abd4-1231390079f2,1218205066272 2008-08-08 10:49:13,310 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: Updates and scanners disabled for region entities,North_America-United_States-Missouri-Oran-b9c7e44a-4a2b-11dd-abd4-1231390079f2,1218205066272 2008-08-08 10:49:13,310 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: waiting for 1 scanners to finish 2008-08-08 10:50:13,306 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Scanner -8330618580557781998 lease expired 2008-08-08 10:50:13,307 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: No more active scanners for region entities,North_America-United_States-Missouri-Oran-b9c7e44a-4a2b-11dd-abd4-1231390079f2,1218205066272 2008-08-08 10:50:13,307 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: No more row locks outstanding on region entities,North_America-United_States-Missouri-Oran-b9c7e44a-4a2b-11dd-abd4-1231390079f2,1218205066272 2008-08-08 10:50:13,307 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: Started memcache flush for region entities,North_America-United_States-Missouri-Oran-b9c7e44a-4a2b-11dd-abd4-1231390079f2,1218205066272. Current region memcache size 3.7m 2008-08-08 10:50:13,821 DEBUG org.apache.hadoop.hbase.regionserver.HStore: Added /hbase/amsterdam_migration/entities/858230020/attribute/mapfiles/5987693228942080783 with 54576 entries, sequence id 9333266, data size 3.7m, file size 4.5m 2008-08-08 10:50:13,821 DEBUG org.apache.hadoop.hbase.regionserver.HRegion: Finished memcache flush for region entities,North_America-United_States-Missouri-Oran-b9c7e44a-4a2b-11dd-abd4-1231390079f2,1218205066272 in 514ms, sequence id=9333266, compaction requested=true 2008-08-08 10:50:13,821 DEBUG org.apache.hadoop.hbase.regionserver.HStore: closed 858230020/attribute 2008-08-08 10:50:13,822 DEBUG org.apache.hadoop.hbase.regionserver.HStore: closed 858230020/context 2008-08-08 10:50:13,822 DEBUG org.apache.hadoop.hbase.regionserver.HStore: closed 858230020/view 2008-08-08 10:50:13,822 INFO org.apache.hadoop.hbase.regionserver.HRegion: closed entities,North_America-United_States-Missouri-Oran-b9c7e44a-4a2b-11dd-abd4-1231390079f2,1218205066272 ... 2008-08-08 10:50:23,437 INFO org.apache.hadoop.ipc.Server: IPC Server handler 2 on 64020, call next(-8330618580557781998) from 192.168.1.84:59678: error: org.apache.hadoop.hbase.UnknownScannerException: Name: -8330618580557781998 org.apache.hadoop.hbase.UnknownScannerException: Name: -8330618580557781998 at org.apache.hadoop.hbase.regionserver.HRegionServer.next(HRegionServer.java:1115) at sun.reflect.GeneratedMethodAccessor6.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$Server.call(HbaseRPC.java:473) at org.apache.hadoop.ipc.Server$Handler.run(Server.java:896)
We have to have some way of telling the client code that it's scanner lease was canceled because of a split so that it stays hidden from the user.