【发布时间】：2013-05-16 14:48:20
【问题描述】：
- 我有一个 3 节点 C* 集群。
- C* 客户端已将读取一致性级别设置为 QUORUM。
- 当集群中的一个节点关闭时，我收到一个 UnavailableException 以响应读取查询
为什么？ 由 3 个节点组成的集群的法定人数为 2，因此它应该处理一个节点的中断。
更多细节：
Cassandra 版本：
ReleaseVersion: 1.1.6
键空间和列族的配置：
Keyspace: QuestionAnswerService:
Replication Strategy: org.apache.cassandra.locator.NetworkTopologyStrategy
Durable Writes: true
Options: [datacenter1:2]
Column Families:
//...
ColumnFamily: answersByQuestion
Key Validation Class: org.apache.cassandra.db.marshal.BytesType
Default column value validator: org.apache.cassandra.db.marshal.BytesType
Columns sorted by: org.apache.cassandra.db.marshal.BytesType
GC grace seconds: 864000
Compaction min/max thresholds: 4/32
Read repair chance: 1.0
DC Local Read repair chance: 0.0
Populate IO Cache on flush: false
Replicate on write: true
Caching: KEYS_ONLY
Bloom Filter FP chance: default
Compaction Strategy: org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy
Compression Options:
sstable_compression: org.apache.cassandra.io.compress.SnappyCompressor
//...
当一个节点关闭时，在读取查询期间抛出异常：
2013-05-21 17:43:37 ERROR CountingConnectionPoolMonitor:81 - com.netflix.astyanax.connectionpool.exceptions.TokenRangeOfflineException: TokenRangeOfflineException: [host=cassandra.xxx.yyy(10.33.0.53):9160, latency=56(56), attempts=1]UnavailableException()
com.netflix.astyanax.connectionpool.exceptions.TokenRangeOfflineException: TokenRangeOfflineException: [host=cassandra.xxx.yyy(10.33.0.53):9160, latency=56(56), attempts=1]UnavailableException()
at com.netflix.astyanax.thrift.ThriftConverter.ToConnectionPoolException(ThriftConverter.java:165)
at com.netflix.astyanax.thrift.AbstractOperationImpl.execute(AbstractOperationImpl.java:60)
at com.netflix.astyanax.thrift.ThriftColumnFamilyQueryImpl$1$2.execute(ThriftColumnFamilyQueryImpl.java:198)
at com.netflix.astyanax.thrift.ThriftColumnFamilyQueryImpl$1$2.execute(ThriftColumnFamilyQueryImpl.java:190)
at com.netflix.astyanax.thrift.ThriftSyncConnectionFactoryImpl$1.execute(ThriftSyncConnectionFactoryImpl.java:136)
at com.netflix.astyanax.connectionpool.impl.AbstractExecuteWithFailoverImpl.tryOperation(AbstractExecuteWithFailoverImpl.java:69)
at com.netflix.astyanax.connectionpool.impl.AbstractHostPartitionConnectionPool.executeWithFailover(AbstractHostPartitionConnectionPool.java:248)
at com.netflix.astyanax.thrift.ThriftColumnFamilyQueryImpl$1.execute(ThriftColumnFamilyQueryImpl.java:188)
at org.example.Casstest$delayedInit$body.apply(Casstest.scala:66)
at scala.Function0$class.apply$mcV$sp(Function0.scala:34)
at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
at scala.App$$anonfun$main$1.apply(App.scala:60)
at scala.App$$anonfun$main$1.apply(App.scala:60)
at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
at scala.collection.immutable.List.foreach(List.scala:45)
at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:30)
at scala.App$class.main(App.scala:60)
at org.example.Casstest$.main(Casstest.scala:14)
at org.example.Casstest.main(Casstest.scala)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
Caused by: UnavailableException()
at org.apache.cassandra.thrift.Cassandra$get_slice_result.read(Cassandra.java:7288)
at org.apache.thrift.TServiceClient.receiveBase(TServiceClient.java:78)
at org.apache.cassandra.thrift.Cassandra$Client.recv_get_slice(Cassandra.java:552)
at org.apache.cassandra.thrift.Cassandra$Client.get_slice(Cassandra.java:536)
at com.netflix.astyanax.thrift.ThriftColumnFamilyQueryImpl$1$2.internalExecute(ThriftColumnFamilyQueryImpl.java:203)
at com.netflix.astyanax.thrift.ThriftColumnFamilyQueryImpl$1$2.internalExecute(ThriftColumnFamilyQueryImpl.java:190)
at com.netflix.astyanax.thrift.AbstractOperationImpl.execute(AbstractOperationImpl.java:55)
... 22 more
重现上述错误的 Scala 代码：
package org.example
import com.netflix.astyanax.connectionpool.impl.{CountingConnectionPoolMonitor, ConnectionPoolConfigurationImpl}
import com.netflix.astyanax.{Keyspace, AstyanaxContext}
import com.netflix.astyanax.impl.AstyanaxConfigurationImpl
import com.netflix.astyanax.connectionpool.NodeDiscoveryType
import com.netflix.astyanax.retry.ConstantBackoff
import com.netflix.astyanax.model.{ColumnFamily, ConsistencyLevel}
import com.netflix.astyanax.thrift.ThriftFamilyFactory
import com.netflix.astyanax.serializers.StringSerializer
import org.slf4j.LoggerFactory
import scala.collection.JavaConversions._
object Casstest extends App {
println("Hello, cass-test")
val logger = LoggerFactory.getLogger(Casstest.getClass)
val clusterName = "Cassandra"
val hostname = "cassandra.xxx.yyy"
val port = 9160
val thriftSocketTimeout = 4000
val keyspaceName = "QuestionAnswerService"
val timeout = 5000
val connectionPool = new ConnectionPoolConfigurationImpl("ConnectionPool")
.setPort(port)
// .setMaxConnsPerHost(1)
.setSeeds(hostname + ":" + port)
.setSocketTimeout(timeout)
.setConnectTimeout(timeout)
.setTimeoutWindow(timeout)
val cassandraContext: AstyanaxContext[Keyspace] =
new AstyanaxContext.Builder()
.forCluster(clusterName)
.withAstyanaxConfiguration(new AstyanaxConfigurationImpl()
.setDiscoveryType(NodeDiscoveryType.TOKEN_AWARE)
.setRetryPolicy(new ConstantBackoff(timeout, 10000))
.setDefaultReadConsistencyLevel(ConsistencyLevel.CL_QUORUM))
.withConnectionPoolConfiguration(connectionPool)
.withConnectionPoolMonitor(new CountingConnectionPoolMonitor())
.forKeyspace(keyspaceName)
.buildKeyspace(ThriftFamilyFactory.getInstance())
cassandraContext.start()
val keyspace: Keyspace = cassandraContext.getEntity()
val answersByQuestionCf = new ColumnFamily[String, String](
"answersByQuestion", // Column Family Name
StringSerializer.get(), // Key Serializer
StringSerializer.get(), // Column Serializer
StringSerializer.get()) // Value Serializer
while(true) {
logger.info("query start")
val result = keyspace
.prepareQuery(answersByQuestionCf)
.getKey("birthyear")
.execute()
logger.info("query finished: " + result.toString)
result.getResult.getColumnNames.take(10) foreach {
logger.info
}
}
}
【问题讨论】：
-
你的所有节点都在datacenter1吗？可以通过cassandra-cli读写吗？
-
是的。更重要的是，我刚刚发现将复制因子增加到 3 可以解决问题 - 我可以成功地在一个节点关闭的情况下进行查询。但是，根据文档，它不应该有所作为。对于 RF = 2 和 RF = 3 QUORUM = 2 链接：datastax.com/docs/1.1/dml/data_consistency [关于读取一致性]