We currently do exactly that. We create multiple instances of TableSnapshotScanner each with a unique dir location against the same snapshot. But doing so gives us the exception mentioned. Does that mean we can’t run multiple instances at the same time? Deepti Bhogle | Senior Software Engineer | Connexity, Inc. Phone: 858.652.4318 | dbho...@connexity.com
On 1/7/16, 3:46 AM, "Enis Söztutar" <e...@apache.org> wrote: >TableSnapshotScanner itself does not support more than one scanner. Are you >creating more than 1 TableSnapshotScanner in your parallel scan? > >Everytime a snapshot scanner is initiated, it will try to "restore" the >snapshot to a temporary location out of the regular root directory in hdfs. >You can try to give different restore directories to each >TableSnapshotScanner. > >Enis > >On Wed, Jan 6, 2016 at 5:51 PM, dbhogle <dbho...@connexity.com> wrote: > >> Using the client api, we can scan the snapshot using a single scanner. We >> currently create an instance of TableSnapshotScanner providing it with a >> unique dir location per scanner. We are currently on cdh 5.4.5 and using >> the >> hbase 1.0.0-cdh5.4.5 api. In order to get desired throughput, we tried to >> increase the number of parallel scanners but raising the no. of scanner >> instances throws the following exception, the occurrence increases as the >> no. of scanners goes up. >> Can the client api support multiple scanners for a single snapshot? >> >> java.io.IOException: java.util.concurrent.ExecutionException: >> >> org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException): >> failed to create file >> >> /hbase/archive/data/default/<tableName>/cb794cfb7948ba8b1f4e73b690dfbfe5/L/.links-a04e1a5b2141445eb1b9e2429f1eced2/cb794cfb7948ba8b1f4e73b690dfbfe5.<tableName> >> for DFSClient_NONMAPREDUCE_672650916_1 for client 10.10.2.90 because >> current >> leaseholder is trying to recreate file. >> at >> >> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.recoverLeaseInternal(FSNamesystem.java:3077) >> at >> >> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal(FSNamesystem.java:2783) >> at >> >> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInt(FSNamesystem.java:2676) >> at >> >> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFile(FSNamesystem.java:2560) >> at >> >> org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.create(NameNodeRpcServer.java:585) >> at >> >> org.apache.hadoop.hdfs.server.namenode.AuthorizationProviderProxyClientProtocol.create(AuthorizationProviderProxyClientProtocol.java:110) >> at >> >> org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.create(ClientNamenodeProtocolServerSideTranslatorPB.java:395) >> at >> >> org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java) >> at >> >> org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:619) >> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1060) >> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2044) >> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2040) >> at java.security.AccessController.doPrivileged(Native Method) >> at javax.security.auth.Subject.doAs(Subject.java:415) >> at >> >> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1671) >> at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2038) >> >> at >> >> org.apache.hadoop.hbase.util.ModifyRegionUtils.createRegions(ModifyRegionUtils.java:162) >> at >> >> org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper.cloneHdfsRegions(RestoreSnapshotHelper.java:561) >> at >> >> org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper.restoreHdfsRegions(RestoreSnapshotHelper.java:237) >> at >> >> org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper.restoreHdfsRegions(RestoreSnapshotHelper.java:159) >> at >> >> org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper.copySnapshotForScanner(RestoreSnapshotHelper.java:812) >> at >> >> org.apache.hadoop.hbase.client.TableSnapshotScanner.init(TableSnapshotScanner.java:156) >> at >> >> org.apache.hadoop.hbase.client.TableSnapshotScanner.<init>(TableSnapshotScanner.java:124) >> at >> >> org.apache.hadoop.hbase.client.TableSnapshotScanner.<init>(TableSnapshotScanner.java:101) >> at >> net.connexity.aro.data.AudienceScanner.join(AudienceScanner.scala:68) >> at >> net.connexity.aro.actor.ScanActor.joinAudience(ScanActor.scala:190) >> at >> >> net.connexity.aro.actor.ScanActor$$anonfun$receive$1.applyOrElse(ScanActor.scala:90) >> at akka.actor.Actor$class.aroundReceive(Actor.scala:467) >> at >> net.connexity.aro.actor.ScanActor.aroundReceive(ScanActor.scala:36) >> at akka.actor.ActorCell.receiveMessage(ActorCell.scala:516) >> at akka.actor.ActorCell.invoke(ActorCell.scala:487) >> at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:238) >> at akka.dispatch.Mailbox.run(Mailbox.scala:220) >> at >> >> akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:397) >> at >> scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260) >> at >> >> scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339) >> at >> scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979) >> at >> >> scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107) >> >> >> >> -- >> View this message in context: >> http://apache-hbase.679495.n3.nabble.com/Parallel-scanning-of-snapshots-using-hbase-client-api-tp4077014.html >> Sent from the HBase Developer mailing list archive at Nabble.com. >>
