[
https://issues.apache.org/jira/browse/HBASE-1207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12720194#action_12720194
]
Jonathan Gray commented on HBASE-1207:
--------------------------------------
I have started up a patch to do what you're describing; reusing the open
scanners, basically diff'ing what has changed rather than rebuilding.
It's certainly possible but requires a bunch of changes, from the
ChangedReadersObserver interface to actually adding some stuff to
KeyValueScanner. The actual modification of the heap should probably actually
happen in the KeyValueHeap. The set of parameters that gets passed through
changed readers to KVHeap is (List<StoreFile> deleted, StoreFile added) where
added always exists but deleted list is sometimes null.
I'm happy to finish the patch, but wanted to know if you still think it's a
good idea given the complexity. It will be far easier to just rebuild the heap
and won't require changing much. Another approach might be to actually do a
"diff", looking at current storefiles against what's in the heap. This will
prevent us from needing to change the changed observer interface but we'll
basically be recalculating what we already know when we make the call to it.
If no one comments I will try to get a patch up later today.
> Fix locking in memcache flush
> -----------------------------
>
> Key: HBASE-1207
> URL: https://issues.apache.org/jira/browse/HBASE-1207
> Project: Hadoop HBase
> Issue Type: Bug
> Affects Versions: 0.19.0
> Reporter: Ben Maurer
> Assignee: Jonathan Gray
> Fix For: 0.20.0
>
>
> memcache flushing holds a write lock while it reopens StoreFileScanners. I
> had a case where this process timed out and caused an exception to be thrown,
> which made the region server believe it had been unable to flush it's cache
> and shut itself down.
> Stack trace is:
> #
> "regionserver/0:0:0:0:0:0:0:0:60020.cacheFlusher" daemon prio=10
> tid=0x00000000562df400 nid=0x15d1 runnable
> [0x000000004108b000..0x000000004108bd90]
> #
> java.lang.Thread.State: RUNNABLE
> #
> at java.util.zip.CRC32.updateBytes(Native Method)
> #
> at java.util.zip.CRC32.update(CRC32.java:45)
> #
> at org.apache.hadoop.util.DataChecksum.update(DataChecksum.java:223)
> #
> at
> org.apache.hadoop.fs.FSInputChecker.readChecksumChunk(FSInputChecker.java:241)
> #
> at org.apache.hadoop.fs.FSInputChecker.fill(FSInputChecker.java:177)
> #
> at org.apache.hadoop.fs.FSInputChecker.read1(FSInputChecker.java:194)
> #
> at org.apache.hadoop.fs.FSInputChecker.read(FSInputChecker.java:159)
> #
> - locked <0x00002aaaec1bd2d8> (a
> org.apache.hadoop.hdfs.DFSClient$BlockReader)
> #
> at
> org.apache.hadoop.hdfs.DFSClient$BlockReader.read(DFSClient.java:1061)
> #
> - locked <0x00002aaaec1bd2d8> (a
> org.apache.hadoop.hdfs.DFSClient$BlockReader)
> #
> at
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.readBuffer(DFSClient.java:1616)
> #
> - locked <0x00002aaad1239000> (a
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream)
> #
> at
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.read(DFSClient.java:1666)
> #
> - locked <0x00002aaad1239000> (a
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream)
> #
> at
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.read(DFSClient.java:1593)
> #
> - locked <0x00002aaad1239000> (a
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream)
> #
> at java.io.DataInputStream.readInt(DataInputStream.java:371)
> #
> at
> org.apache.hadoop.hbase.io.SequenceFile$Reader.next(SequenceFile.java:1943)
> #
> - locked <0x00002aaad1238c38> (a
> org.apache.hadoop.hbase.io.SequenceFile$Reader)
> #
> at
> org.apache.hadoop.hbase.io.SequenceFile$Reader.next(SequenceFile.java:1844)
> #
> - locked <0x00002aaad1238c38> (a
> org.apache.hadoop.hbase.io.SequenceFile$Reader)
> #
> at
> org.apache.hadoop.hbase.io.SequenceFile$Reader.next(SequenceFile.java:1890)
> #
> - locked <0x00002aaad1238c38> (a
> org.apache.hadoop.hbase.io.SequenceFile$Reader)
> #
> at org.apache.hadoop.hbase.io.MapFile$Reader.next(MapFile.java:525)
> #
> - locked <0x00002aaad1238b80> (a
> org.apache.hadoop.hbase.io.HalfMapFileReader)
> #
> at
> org.apache.hadoop.hbase.io.HalfMapFileReader.next(HalfMapFileReader.java:192)
> #
> - locked <0x00002aaad1238b80> (a
> org.apache.hadoop.hbase.io.HalfMapFileReader)
> #
> at
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.getNext(StoreFileScanner.java:312)
> #
> at
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.openReaders(StoreFileScanner.java:110)
> #
> at
> org.apache.hadoop.hbase.regionserver.StoreFileScanner.updateReaders(StoreFileScanner.java:378)
> #
> at
> org.apache.hadoop.hbase.regionserver.HStore.notifyChangedReadersObservers(HStore.java:737)
> #
> at
> org.apache.hadoop.hbase.regionserver.HStore.updateReaders(HStore.java:725)
> #
> at
> org.apache.hadoop.hbase.regionserver.HStore.internalFlushCache(HStore.java:694)
> #
> - locked <0x00002aaab7b41d30> (a java.lang.Integer)
> #
> at
> org.apache.hadoop.hbase.regionserver.HStore.flushCache(HStore.java:630)
> #
> at
> org.apache.hadoop.hbase.regionserver.HRegion.internalFlushcache(HRegion.java:881)
> #
> at
> org.apache.hadoop.hbase.regionserver.HRegion.flushcache(HRegion.java:789)
> #
> at
> org.apache.hadoop.hbase.regionserver.MemcacheFlusher.flushRegion(MemcacheFlusher.java:227)
> #
> at
> org.apache.hadoop.hbase.regionserver.MemcacheFlusher.run(MemcacheFlusher.java:137)
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
