【发布时间】：2014-10-12 10:40:25
【问题描述】：
也许我误解了 Astyanax Cassandra API 中的自动节点发现是如何工作的， 但这是我的问题：
我有以下设置：
2 个数据中心，每个数据中心有 2 个节点，复制因子为 2。
DC1：N1 和 N2 和 DC2：N3 和 N4
种子节点是 N1 和 N3（也提供给应用程序）。 其他节点（N2 和 N4）的自动发现似乎有效。即使它们没有显示在主机池中。
如果 N3 失败，则数据正确写入 N4，并且在节点再次启动时也正确同步到 N3。 N1 和 N2 也是如此。
当两个种子节点（N1 和 N3）都失败时，就会出现问题。然后数据不再写入 N2 和 N4（如预期的那样），但异常导致应用程序失败（Astyanax 将异常信息写入日志，当一个种子节点关闭时，但这通常不会导致申请失败）。
很明显，应用程序启动时种子节点必须在线，但我认为astyanax中的自动节点发现会允许种子节点失败，以便复制节点可以接管（使用一致性级别CL_ONE)。
有没有办法避免这个故障，还是我只是误解了自动节点发现， 还是我只是做错了什么？
一些附加信息： 节点主要使用 cassandra.yaml 中的默认设置，并且令牌是使用 python 脚本生成的， 在文档中提出。
private AstyanaxContext<Cluster> connect(final String hosts) {
AstyanaxConfigurationImpl asConfig = new AstyanaxConfigurationImpl();
asConfig.setDefaultWriteConsistencyLevel(ConsistencyLevel.CL_ONE);
asConfig.setDefaultReadConsistencyLevel(ConsistencyLevel.CL_ONE);
AstyanaxContext<Cluster> context = new AstyanaxContext.Builder()
.forCluster("TestSuitCluster")
.withAstyanaxConfiguration(
asConfig.setDiscoveryType(NodeDiscoveryType.TOKEN_AWARE)
.setConnectionPoolType(ConnectionPoolType.TOKEN_AWARE))
.withConnectionPoolConfiguration(
new ConnectionPoolConfigurationImpl(
"CassandraConnectionPool").setSeeds(hosts)
.setMaxConnsPerHost(8).setMaxConns(8))
.withConnectionPoolMonitor(new ConnectionPoolMonitor())
.buildCluster(ThriftFamilyFactory.getInstance());
context.start();
return context;
}
当最后一个种子节点脱落时显示的堆栈跟踪：
com.netflix.astyanax.connectionpool.exceptions.PoolTimeoutException: PoolTimeoutException: [host=127.0.0.1(127.0.0.1):9160, latency=2000(2000), attempts=1]Timed out waiting for connection
at com.netflix.astyanax.connectionpool.impl.SimpleHostConnectionPool.waitForConnection(SimpleHostConnectionPool.java:218)
at com.netflix.astyanax.connectionpool.impl.SimpleHostConnectionPool.borrowConnection(SimpleHostConnectionPool.java:185)
at com.netflix.astyanax.connectionpool.impl.RoundRobinExecuteWithFailover.borrowConnection(RoundRobinExecuteWithFailover.java:66)
at com.netflix.astyanax.connectionpool.impl.AbstractExecuteWithFailoverImpl.tryOperation(AbstractExecuteWithFailoverImpl.java:67)
at com.netflix.astyanax.connectionpool.impl.AbstractHostPartitionConnectionPool.executeWithFailover(AbstractHostPartitionConnectionPool.java:256)
at com.netflix.astyanax.thrift.ThriftClusterImpl.describeKeyspaces(ThriftClusterImpl.java:165)
at com.netflix.astyanax.thrift.ThriftClusterImpl.describeKeyspace(ThriftClusterImpl.java:184)
at at.dbeg.cassandra.CasandraTestSuit.deleteKeyspace(CasandraTestSuit.java:134)
at at.dbeg.cassandra.CasandraTestSuit.runTests(CasandraTestSuit.java:189)
at at.dbeg.cassandra.CasandraTestSuit.main(CasandraTestSuit.java:50)
com.netflix.astyanax.connectionpool.exceptions.ConnectionAbortedException: ConnectionAbortedException: [host=127.0.0.1(127.0.0.1):9160, latency=0(0), attempts=1]org.apache.thrift.transport.TTransportException: java.net.SocketException: Connection reset by peer: socket write error
at com.netflix.astyanax.thrift.ThriftConverter.ToConnectionPoolException(ThriftConverter.java:193)
at com.netflix.astyanax.thrift.AbstractOperationImpl.execute(AbstractOperationImpl.java:65)
at com.netflix.astyanax.thrift.AbstractOperationImpl.execute(AbstractOperationImpl.java:28)
at com.netflix.astyanax.thrift.ThriftSyncConnectionFactoryImpl$ThriftConnection.execute(ThriftSyncConnectionFactoryImpl.java:151)
at com.netflix.astyanax.connectionpool.impl.AbstractExecuteWithFailoverImpl.tryOperation(AbstractExecuteWithFailoverImpl.java:69)
at com.netflix.astyanax.connectionpool.impl.AbstractHostPartitionConnectionPool.executeWithFailover(AbstractHostPartitionConnectionPool.java:256)
at com.netflix.astyanax.thrift.ThriftKeyspaceImpl.executeOperation(ThriftKeyspaceImpl.java:485)
at com.netflix.astyanax.thrift.ThriftKeyspaceImpl.access$000(ThriftKeyspaceImpl.java:79)
at com.netflix.astyanax.thrift.ThriftKeyspaceImpl$6$3.execute(ThriftKeyspaceImpl.java:355)
at at.dbeg.cassandra.CasandraTestSuit.testWrite(CasandraTestSuit.java:269)
at at.dbeg.cassandra.CasandraTestSuit.runTests(CasandraTestSuit.java:168)
at at.dbeg.cassandra.CasandraTestSuit.main(CasandraTestSuit.java:50)
Caused by: org.apache.thrift.transport.TTransportException: java.net.SocketException: Connection reset by peer: socket write error
at org.apache.thrift.transport.TIOStreamTransport.write(TIOStreamTransport.java:147)
at org.apache.thrift.transport.TFramedTransport.flush(TFramedTransport.java:156)
at org.apache.thrift.TServiceClient.sendBase(TServiceClient.java:65)
at org.apache.cassandra.thrift.Cassandra$Client.send_insert(Cassandra.java:833)
at org.apache.cassandra.thrift.Cassandra$Client.insert(Cassandra.java:822)
at com.netflix.astyanax.thrift.ThriftKeyspaceImpl$6$3$1.internalExecute(ThriftKeyspaceImpl.java:367)
at com.netflix.astyanax.thrift.ThriftKeyspaceImpl$6$3$1.internalExecute(ThriftKeyspaceImpl.java:358)
at com.netflix.astyanax.thrift.AbstractOperationImpl.execute(AbstractOperationImpl.java:60)
... 10 more
Caused by: java.net.SocketException: Connection reset by peer: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:113)
at java.net.SocketOutputStream.write(SocketOutputStream.java:159)
at org.apache.thrift.transport.TIOStreamTransport.write(TIOStreamTransport.java:145)
... 17 more
【问题讨论】：