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https://issues.apache.org/jira/browse/HBASE-26482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17447819#comment-17447819
]
Duo Zhang commented on HBASE-26482:
-----------------------------------
I think this is definately a problem...
> HMaster may clean wals that is replicating in rare cases
> --------------------------------------------------------
>
> Key: HBASE-26482
> URL: https://issues.apache.org/jira/browse/HBASE-26482
> Project: HBase
> Issue Type: Bug
> Components: Replication
> Reporter: zhuobin zheng
> Priority: Critical
>
> In our cluster, i can found some FileNotFoundException when
> ReplicationSourceWALReader running for replication recovery queue.
> I guss the wal most likely removed by hmaste. And i found something to
> support it.
> The method getAllWALs:
> [https://github.com/apache/hbase/blob/master/hbase-replication/src/main/java/org/apache/hadoop/hbase/replication/ZKReplicationQueueStorage.java#L509
>
> |https://github.com/apache/hbase/blob/master/hbase-replication/src/main/java/org/apache/hadoop/hbase/replication/ZKReplicationQueueStorage.java#L509]Use
> zk cversion of /hbase/replication/rs as an optimistic lock to control
> concurrent ops.
> But, zk cversion *only can only reflect the changes of child nodes, but not
> the changes of grandchildren.*
> So, HMaster may loss some wal from this method in follow situation.
> # HMaster do log clean , and invoke getAllWALs to filter log which should
> not be deleted.
> # HMaster cache current cversion of /hbase/replication/rs as *v0*
> # HMaster cache all RS server name, and traverse them, get the WAL in each
> Queue
> # *RS2* dead after HMaster traverse {*}RS1{*}, and before traverse *RS2*
> # *RS1* claim one queue of *RS2,* which named *peerid-RS2* now
> # By the way , the cversion of /hbase/replication/rs not changed before all
> of *RS2* queue is removed, because the children of /hbase/replication/rs not
> change.
> # So, Hmaster will lost the wals in *peerid-RS2,* because we have already
> traversed *RS1 ,* and ** this queue not exists in *RS2*
> The above expression is currently only speculation, not confirmed
> Flie Not Found Log.
>
> {code:java}
> // code placeholder
> 2021-11-22 15:18:39,593 ERROR
> [ReplicationExecutor-0.replicationSource,peer_id-hostname,60020,1636802867348.replicationSource.wal-reader.hostname%2C60020%2C1636802867348,peer_id-hostname,60020,1636802867348]
> regionserver.WALEntryStream: Couldn't locate log:
> hdfs://namenode/hbase/oldWALs/hostname%2C60020%2C1636802867348.1636944748704
> 2021-11-22 15:18:39,593 ERROR
> [ReplicationExecutor-0.replicationSource,peer_id-hostname,60020,1636802867348.replicationSource.wal-reader.hostname%2C60020%2C1636802867348,peer_id-hostname,60020,1636802867348]
> regionserver.ReplicationSourceWALReader: Failed to read stream of
> replication entries
> java.io.FileNotFoundException: File does not exist:
> hdfs://namenode/hbase/oldWALs/hostname%2C60020%2C1636802867348.1636944748704
> at
> org.apache.hadoop.hdfs.DistributedFileSystem$29.doCall(DistributedFileSystem.java:1612)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem$29.doCall(DistributedFileSystem.java:1605)
> at
> org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1620)
> at
> org.apache.hadoop.hbase.regionserver.wal.ReaderBase.init(ReaderBase.java:64)
> at
> org.apache.hadoop.hbase.regionserver.wal.ProtobufLogReader.init(ProtobufLogReader.java:168)
> at
> org.apache.hadoop.hbase.wal.WALFactory.createReader(WALFactory.java:321)
> at
> org.apache.hadoop.hbase.wal.WALFactory.createReader(WALFactory.java:303)
> at
> org.apache.hadoop.hbase.wal.WALFactory.createReader(WALFactory.java:291)
> at
> org.apache.hadoop.hbase.wal.WALFactory.createReader(WALFactory.java:427)
> at
> org.apache.hadoop.hbase.replication.regionserver.WALEntryStream.openReader(WALEntryStream.java:355)
> at
> org.apache.hadoop.hbase.replication.regionserver.WALEntryStream.openNextLog(WALEntryStream.java:303)
> at
> org.apache.hadoop.hbase.replication.regionserver.WALEntryStream.checkReader(WALEntryStream.java:294)
> at
> org.apache.hadoop.hbase.replication.regionserver.WALEntryStream.tryAdvanceEntry(WALEntryStream.java:175)
> at
> org.apache.hadoop.hbase.replication.regionserver.WALEntryStream.hasNext(WALEntryStream.java:101)
> at
> org.apache.hadoop.hbase.replication.regionserver.ReplicationSourceWALReader.readWALEntries(ReplicationSourceWALReader.java:192)
> at
> org.apache.hadoop.hbase.replication.regionserver.ReplicationSourceWALReader.run(ReplicationSourceWALReader.java:138)
> {code}
>
>
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