HBase Master 无法启动

Question

我在 CDH 集群 5.7.0 中运行 HBase。在运行了几个月没有任何问题后，hbase 服务停止了，现在无法启动 HBase 主服务器（1 个主服务器和 4 个区域服务器）。

当我尝试在某个时候启动它时，机器挂起，我在主日志中看到的最后一件事是：

2016-10-24 12:17:15,150 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recover lease on dfs file hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005528.log
2016-10-24 12:17:15,152 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recovered lease, attempt=0 on file=hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005528.log after 2ms
2016-10-24 12:17:15,177 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recover lease on dfs file hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005529.log
2016-10-24 12:17:15,179 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recovered lease, attempt=0 on file=hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005529.log after 2ms
2016-10-24 12:17:15,394 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recover lease on dfs file hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005530.log
2016-10-24 12:17:15,397 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recovered lease, attempt=0 on file=hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005530.log after 3ms
2016-10-24 12:17:15,405 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recover lease on dfs file hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005531.log
2016-10-24 12:17:15,409 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recovered lease, attempt=0 on file=hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005531.log after 3ms
2016-10-24 12:17:15,414 WARN org.apache.hadoop.hdfs.BlockReaderFactory: I/O error constructing remote block reader.
java.net.SocketException: No buffer space available
    at sun.nio.ch.Net.connect0(Native Method)
    at sun.nio.ch.Net.connect(Net.java:465)
    at sun.nio.ch.Net.connect(Net.java:457)
    at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:670)
    at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:192)
    at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:530)
    at org.apache.hadoop.hdfs.DFSClient.newConnectedPeer(DFSClient.java:3499)
    at org.apache.hadoop.hdfs.BlockReaderFactory.nextTcpPeer(BlockReaderFactory.java:838)
    at org.apache.hadoop.hdfs.BlockReaderFactory.getRemoteBlockReaderFromTcp(BlockReaderFactory.java:753)
    at org.apache.hadoop.hdfs.BlockReaderFactory.build(BlockReaderFactory.java:374)
    at org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:662)
    at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:889)
    at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:942)
    at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:742)
    at java.io.FilterInputStream.read(FilterInputStream.java:83)
    at com.google.protobuf.AbstractParser.parsePartialDelimitedFrom(AbstractParser.java:232)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:253)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:259)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:49)
    at org.apache.hadoop.hbase.protobuf.generated.ProcedureProtos$ProcedureWALHeader.parseDelimitedFrom(ProcedureProtos.java:3870)
    at org.apache.hadoop.hbase.procedure2.store.wal.ProcedureWALFormat.readHeader(ProcedureWALFormat.java:138)
    at org.apache.hadoop.hbase.procedure2.store.wal.ProcedureWALFile.open(ProcedureWALFile.java:76)
    at org.apache.hadoop.hbase.procedure2.store.wal.WALProcedureStore.initOldLog(WALProcedureStore.java:1006)
    at org.apache.hadoop.hbase.procedure2.store.wal.WALProcedureStore.initOldLogs(WALProcedureStore.java:969)
    at org.apache.hadoop.hbase.procedure2.store.wal.WALProcedureStore.recoverLease(WALProcedureStore.java:300)
    at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.start(ProcedureExecutor.java:509)
    at org.apache.hadoop.hbase.master.HMaster.startProcedureExecutor(HMaster.java:1175)
    at org.apache.hadoop.hbase.master.HMaster.startServiceThreads(HMaster.java:1097)
    at org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:681)
    at org.apache.hadoop.hbase.master.HMaster.access$500(HMaster.java:187)
    at org.apache.hadoop.hbase.master.HMaster$1.run(HMaster.java:1756)
    at java.lang.Thread.run(Thread.java:745)
2016-10-24 12:17:15,427 WARN org.apache.hadoop.hdfs.DFSClient: Failed to connect to /xxx.xxx.xxx.xxx:50010 for block, add to deadNodes and continue. java.net.SocketException: No buffer space available
java.net.SocketException: No buffer space available
    at sun.nio.ch.Net.connect0(Native Method)
    at sun.nio.ch.Net.connect(Net.java:465)
    at sun.nio.ch.Net.connect(Net.java:457)
    at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:670)
    at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:192)
    at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:530)
    at org.apache.hadoop.hdfs.DFSClient.newConnectedPeer(DFSClient.java:3499)
    at org.apache.hadoop.hdfs.BlockReaderFactory.nextTcpPeer(BlockReaderFactory.java:838)
    at org.apache.hadoop.hdfs.BlockReaderFactory.getRemoteBlockReaderFromTcp(BlockReaderFactory.java:753)
    at org.apache.hadoop.hdfs.BlockReaderFactory.build(BlockReaderFactory.java:374)
    at org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:662)
    at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:889)
    at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:942)
    at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:742)
    at java.io.FilterInputStream.read(FilterInputStream.java:83)
    at com.google.protobuf.AbstractParser.parsePartialDelimitedFrom(AbstractParser.java:232)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:253)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:259)
    at com.google.protobuf.AbstractParser.parseDelimitedFrom(AbstractParser.java:49)
    at org.apache.hadoop.hbase.protobuf.generated.ProcedureProtos$ProcedureWALHeader.parseDelimitedFrom(ProcedureProtos.java:3870)
    at org.apache.hadoop.hbase.procedure2.store.wal.ProcedureWALFormat.readHeader(ProcedureWALFormat.java:138)
    at org.apache.hadoop.hbase.procedure2.store.wal.ProcedureWALFile.open(ProcedureWALFile.java:76)
    at org.apache.hadoop.hbase.procedure2.store.wal.WALProcedureStore.initOldLog(WALProcedureStore.java:1006)
    at org.apache.hadoop.hbase.procedure2.store.wal.WALProcedureStore.initOldLogs(WALProcedureStore.java:969)
    at org.apache.hadoop.hbase.procedure2.store.wal.WALProcedureStore.recoverLease(WALProcedureStore.java:300)
    at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.start(ProcedureExecutor.java:509)
    at org.apache.hadoop.hbase.master.HMaster.startProcedureExecutor(HMaster.java:1175)
    at org.apache.hadoop.hbase.master.HMaster.startServiceThreads(HMaster.java:1097)
    at org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:681)
    at org.apache.hadoop.hbase.master.HMaster.access$500(HMaster.java:187)
    at org.apache.hadoop.hbase.master.HMaster$1.run(HMaster.java:1756)
    at java.lang.Thread.run(Thread.java:745)
2016-10-24 12:17:15,436 INFO org.apache.hadoop.hdfs.DFSClient: Successfully connected to /xxx.xxx.xxx.xxx:50010 for BP-813663273-xxx.xxx.xxx.xxx-1460963038761:blk_1079056868_5316127
2016-10-24 12:17:15,442 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recover lease on dfs file hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005532.log
2016-10-24 12:17:15,444 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recovered lease, attempt=0 on file=hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005532.log after 2ms
2016-10-24 12:17:15,669 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recover lease on dfs file hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005533.log
2016-10-24 12:17:15,672 INFO org.apache.hadoop.hbase.util.FSHDFSUtils: Recovered lease, attempt=0 on file=hdfs://namenode:8020/hbase/MasterProcWALs/state-00000000000000005533.log after 2ms 

我担心 WALProcedureStore 中的某些内容已损坏，但我不知道如何继续挖掘以找出问题所在。有什么线索吗？我可以在不尝试加载之前损坏的状态的情况下重新启动 Master 吗？

编辑：

我刚刚看到this bug，我认为这与发生在我身上的问题相同。我可以安全地删除 /hbase/MasterProcWALs 中的所有内容而不删除存储在 hbase 中的旧数据吗？

没有

谢谢

Answer 1

WAL 或 Write-Ahead-Log 是一种 HBase 机制，能够在一切崩溃时恢复对数据的修改。基本上，对 HBase 的每个写入操作都会事先记录在 WAL 中，如果系统崩溃并且数据仍然没有持久化，那么 HBase 将能够从 WAL 重新创建这些写入。

这个article帮助我更好地理解了整个过程：

WAL 是灾难发生时所需的生命线。类似于 MySQL 中的 BIN 日志，它记录对数据的所有更改。如果主存储发生问题，这很重要。因此，如果服务器崩溃，它可以有效地重播该日志，以使所有内容都恢复到服务器在崩溃之前应该处于的位置。这也意味着如果将记录写入 WAL 失败，则必须将整个操作视为失败。

让我们看一下如何在 HBase 中完成此操作的高级视图。首先，客户端启动一个修改数据的操作。目前这是对 put(Put)、delete(Delete) 和 incrementColumnValue() 的调用（有时缩写为“incr”）。这些修改中的每一个都被包装到一个 KeyValue 对象实例中，并使用 RPC 调用通过网络发送。调用（理想情况下是批处理）到为受影响区域提供服务的 HRegionServer。一旦它到达有效载荷，即所述 KeyValue，被路由到负责受影响行的 HRegion。数据被写入 WAL，然后放入保存记录的实际 Store 的 MemStore。这也几乎描述了 write- HBase 的路径。

最终，当 MemStore 达到特定大小或特定时间后，数据将异步持久化到文件系统。在该时间范围之间，数据易失性地存储在内存中。如果托管该内存的 HRegionServer 崩溃，则数据会丢失......但是对于这篇文章的主题，WAL 的存在！

这里的问题是，由于this bug (HBASE-14712)，WAL 最终拥有数千条日志。每次 master 尝试变得活跃时，它都有许多不同的日志要恢复、租用和读取……最终导致 namenode 被破坏。它用完了 tcp 缓冲区空间，一切都崩溃了。

为了能够启动 master，我必须手动删除 /hbase/MasterProcWALs 和 /hbase/WALs 下的日志。完成此操作后，master 能够变为活动状态，并且 HBase 集群重新上线。

编辑：

正如 Ankit Singhai 指出的，删除 /hbase/WALs 中的日志会导致数据丢失。只删除 /hbase/MasterProcWALs 中的日志应该没问题。