我将以下代码作为java程序运行。查询运行无限次，即使它只调用一次，我无法弄清楚原因。它在第一次查询期间丢弃了键空间，当它再次运行时（它不应该运行），它会不断地给出异常，键空间不存在。
如何才能使查询只运行一次？
Session session=cassandraSessionFactory.getSession();
String query = "drop keyspace "+keyspace_name";
session.execute(query);
session.close();
这是异常堆栈跟踪，它继续多次打印并仅在手动暂停时停止。
23:24:55,654 INFO BackendOperation:75 - Temporary exception during backend operation [messageReading@0:0]. Attempting backoff retry.
com.thinkaurelius.titan.diskstorage.TemporaryBackendException: Temporary failure in storage backend
at com.thinkaurelius.titan.diskstorage.cassandra.astyanax.AstyanaxKeyColumnValueStore.getNamesSlice(AstyanaxKeyColumnValueStore.java:114)
at com.thinkaurelius.titan.diskstorage.cassandra.astyanax.AstyanaxKeyColumnValueStore.getNamesSlice(AstyanaxKeyColumnValueStore.java:78)
at com.thinkaurelius.titan.diskstorage.cassandra.astyanax.AstyanaxKeyColumnValueStore.getSlice(AstyanaxKeyColumnValueStore.java:67)
at com.thinkaurelius.titan.diskstorage.log.kcvs.KCVSLog$MessagePuller$1.call(KCVSLog.java:769)
at com.thinkaurelius.titan.diskstorage.log.kcvs.KCVSLog$MessagePuller$1.call(KCVSLog.java:766)
at com.thinkaurelius.titan.diskstorage.util.BackendOperation.execute(BackendOperation.java:133)
at com.thinkaurelius.titan.diskstorage.util.BackendOperation$1.call(BackendOperation.java:147)
at com.thinkaurelius.titan.diskstorage.util.BackendOperation.executeDirect(BackendOperation.java:56)
at com.thinkaurelius.titan.diskstorage.util.BackendOperation.execute(BackendOperation.java:42)
at com.thinkaurelius.titan.diskstorage.util.BackendOperation.execute(BackendOperation.java:144)
at com.thinkaurelius.titan.diskstorage.log.kcvs.KCVSLog$MessagePuller.run(KCVSLog.java:703)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: com.netflix.astyanax.connectionpool.exceptions.BadRequestException: BadRequestException: [host=127.0.0.1(127.0.0.1):9160, latency=0(0), attempts=1]InvalidRequestException(why:Keyspace keyspace_name does not exist)
at com.netflix.astyanax.thrift.ThriftConverter.ToConnectionPoolException(ThriftConverter.java:159)
at com.netflix.astyanax.thrift.AbstractOperationImpl.execute(AbstractOperationImpl.java:65)
at com.netflix.astyanax.thrift.AbstractOperationImpl.execute(AbstractOperationImpl.java:28)
at com.netflix.astyanax.thrift.ThriftSyncConnectionFactoryImpl$ThriftConnection.execute(ThriftSyncConnectionFactoryImpl.java:153)
at com.netflix.astyanax.connectionpool.impl.AbstractExecuteWithFailoverImpl.tryOperation(AbstractExecuteWithFailoverImpl.java:119)
at com.netflix.astyanax.connectionpool.impl.AbstractHostPartitionConnectionPool.executeWithFailover(AbstractHostPartitionConnectionPool.java:352)
at com.netflix.astyanax.thrift.ThriftColumnFamilyQueryImpl$4.execute(ThriftColumnFamilyQueryImpl.java:538)
at com.thinkaurelius.titan.diskstorage.cassandra.astyanax.AstyanaxKeyColumnValueStore.getNamesSlice(AstyanaxKeyColumnValueStore.java:112)
... 17 more
Caused by: InvalidRequestException(why:Keyspace keyspace_name does not exist)
at org.apache.cassandra.thrift.Cassandra$multiget_slice_result$multiget_slice_resultStandardScheme.read(Cassandra.java:14678)
at org.apache.cassandra.thrift.Cassandra$multiget_slice_result$multiget_slice_resultStandardScheme.read(Cassandra.java:14633)
at org.apache.cassandra.thrift.Cassandra$multiget_slice_result.read(Cassandra.java:14559)
at org.apache.thrift.TServiceClient.receiveBase(TServiceClient.java:78)
at org.apache.cassandra.thrift.Cassandra$Client.recv_multiget_slice(Cassandra.java:741)
at org.apache.cassandra.thrift.Cassandra$Client.multiget_slice(Cassandra.java:725)
at com.netflix.astyanax.thrift.ThriftColumnFamilyQueryImpl$4$1.internalExecute(ThriftColumnFamilyQueryImpl.java:544)
at com.netflix.astyanax.thrift.ThriftColumnFamilyQueryImpl$4$1.internalExecute(ThriftColumnFamilyQueryImpl.java:541)
at com.netflix.astyanax.thrift.AbstractOperationImpl.execute(AbstractOperationImpl.java:60)
... 23 more