这个就是兜底用的，如果发生了说明代码有 bug
leojie <leo...@apache.org> 于2023年1月28日周六 11:14写道：
>
> 感谢张老师的回复，再请教一下，BlockCacheUtil类中的validateBlockAddition方法内，
>
> public static int validateBlockAddition(Cacheable existing, Cacheable
> newBlock,
> BlockCacheKey cacheKey) {
> int comparison = compareCacheBlock(existing, newBlock, false);
> if (comparison != 0) {
> throw new RuntimeException(
> "Cached block contents differ, which should not have happened."
> + "cacheKey:" + cacheKey);
> }
> if ((existing instanceof HFileBlock) && (newBlock instanceof HFileBlock)) {
> comparison = ((HFileBlock) existing).getNextBlockOnDiskSize()
> - ((HFileBlock) newBlock).getNextBlockOnDiskSize();
> }
> return comparison;
> }
>
> 这里comparison != 0这个判断逻辑是必须的？
>
>
> 张铎(Duo Zhang) <palomino...@gmail.com> 于2023年1月28日周六 11:09写道：
>
> > 建议先升级到2.4或者2.5的最新版试试？2.2.6 已经是比较老的版本了，后面 BucketCache 修过不少小 bug
> >
> > https://issues.apache.org/jira/browse/HBASE-26281
> >
> > 比如这个就有可能导致BucketCache里的内容错乱，出现各种奇怪的错误
> >
> > leojie <leo...@apache.org> 于2023年1月28日周六 10:22写道：
> >
> > >
> > > Hi all，
> > > 向社区求助一个HBase的scan异常导致RS宕机的问题，异常日志如下：
> > >
> > > 2023-01-19 03:19:06,986 ERROR
> > > [RpcServer.default.RWQ.Fifo.scan.handler=226,queue=19,port=60020]
> > > ipc.RpcServer: Unexpected throwable object
> > > java.lang.RuntimeException: Cached block contents differ, which should
> > not
> > > have happened.cacheKey:bbec4ed53b6d475cbb8711f183556eb0_14145152
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.BlockCacheUtil.validateBlockAddition(BlockCacheUtil.java:205)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.BlockCacheUtil.shouldReplaceExistingCacheBlock(BlockCacheUtil.java:237)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.bucket.BucketCache.shouldReplaceExistingCacheBlock(BucketCache.java:432)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.bucket.BucketCache.cacheBlockWithWait(BucketCache.java:417)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.bucket.BucketCache.cacheBlock(BucketCache.java:403)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.CombinedBlockCache.cacheBlock(CombinedBlockCache.java:68)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.HFileReaderImpl.lambda$readBlock$2(HFileReaderImpl.java:1528)
> > > at java.util.Optional.ifPresent(Optional.java:159)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.HFileReaderImpl.readBlock(HFileReaderImpl.java:1526)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.HFileReaderImpl$HFileScannerImpl.readNextDataBlock(HFileReaderImpl.java:928)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.HFileReaderImpl$HFileScannerImpl.isNextBlock(HFileReaderImpl.java:1061)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.HFileReaderImpl$HFileScannerImpl.positionForNextBlock(HFileReaderImpl.java:1055)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.HFileReaderImpl$HFileScannerImpl._next(HFileReaderImpl.java:1073)
> > > at
> > > org.apache.hadoop.hbase.io
> > .hfile.HFileReaderImpl$HFileScannerImpl.next(HFileReaderImpl.java:1094)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.StoreFileScanner.reseekAtOrAfter(StoreFileScanner.java:351)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.StoreFileScanner.reseek(StoreFileScanner.java:244)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.NonLazyKeyValueScanner.doRealSeek(NonLazyKeyValueScanner.java:55)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.KeyValueHeap.generalizedSeek(KeyValueHeap.java:324)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.KeyValueHeap.reseek(KeyValueHeap.java:267)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.StoreScanner.reseek(StoreScanner.java:1099)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.StoreScanner.seekAsDirection(StoreScanner.java:1088)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.StoreScanner.seekOrSkipToNextColumn(StoreScanner.java:823)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.StoreScanner.next(StoreScanner.java:730)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.KeyValueHeap.next(KeyValueHeap.java:157)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.populateResult(HRegion.java:6681)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextInternal(HRegion.java:6845)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextRaw(HRegion.java:6615)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.RSRpcServices.scan(RSRpcServices.java:3238)
> > > at
> > >
> > org.apache.hadoop.hbase.regionserver.RSRpcServices.scan(RSRpcServices.java:3483)
> > > at
> > >
> > org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:42278)
> > > at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:379)
> > > at
> > org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:133)
> > > at
> > > org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:338)
> > > at
> > > org.apache.hadoop.hbase.ipc.RpcExecutor$Handler.run(RpcExecutor.java:318)
> > >
> > > 对应的源码（2.2.6）：
> > >
> > > public static int validateBlockAddition(Cacheable existing, Cacheable
> > newBlock,
> > > BlockCacheKey cacheKey) {
> > > int comparison = compareCacheBlock(existing, newBlock, false);
> > > if (comparison != 0) {
> > > throw new RuntimeException(
> > > "Cached block contents differ, which should not have happened."
> > > + "cacheKey:" + cacheKey);
> > > }
> > > if ((existing instanceof HFileBlock) && (newBlock instanceof
> > HFileBlock)) {
> > > comparison = ((HFileBlock) existing).getNextBlockOnDiskSize()
> > > - ((HFileBlock) newBlock).getNextBlockOnDiskSize();
> > > }
> > > return comparison;
> > > }
> > >
> > >
> > > scan操作的缓存置换过程中，触发了一个未捕获的RunTime异常，导致RS突然宕机，请教一下，什么情况会触发此异常，然后如何避免此异常的发生呢？
> >
