这是一个关于springxdrelease1.0.1与maprfs协同工作的问题，目前官方还不支持maprfs。但我还是想让它发挥作用。
我们就是这么做的：
1） 调整了xd shell、xd worker和xd singlenode shell脚本以接受参数 --hadoopDistro mapr 2） 向新目录$xd\u home/lib/mapr添加了库

avro-1.7.4.jar                              jersey-core-1.9.jar
hadoop-annotations-2.2.0.jar                jersey-server-1.9.jar
hadoop-core-1.0.3-mapr-3.0.2.jar            jetty-util-6.1.26.jar
hadoop-distcp-2.2.0.jar                     maprfs-1.0.3-mapr-3.0.2.jar
hadoop-hdfs-2.2.0.jar                       protobuf-java-2.5.0.jar
hadoop-mapreduce-client-core-2.2.0.jar      spring-data-hadoop-2.0.2.RELEASE-hadoop24.jar
hadoop-streaming-2.2.0.jar                  spring-data-hadoop-batch-2.0.2.RELEASE-hadoop24.jar
hadoop-yarn-api-2.2.0.jar                   spring-data-hadoop-core-2.0.2.RELEASE-hadoop24.jar
hadoop-yarn-common-2.2.0.jar                spring-data-hadoop-store-2.0.2.RELEASE-hadoop24.jar

3） 跑 bin/xd-singlenode --hadoopDistro mapr 以及 shell/bin/xd-shell --hadoopDistro mapr .
通过创建和部署流时 stream create foo --definition "time | hdfs" --deploy ，数据将写入maprfs上的tmp/xd/foo/foo-1.txt.tmp文件。但是，在取消部署流时，会出现以下异常：

org.springframework.data.hadoop.store.StoreException: Failed renaming from /xd/foo/foo-1.txt.tmp to /xd/foo/foo-1.txt; nested exception is java.io.FileNotFoundException: Requested file /xd/foo/foo-1.txt does not exist.
at org.springframework.data.hadoop.store.support.OutputStoreObjectSupport.renameFile(OutputStoreObjectSupport.java:261)
at org.springframework.data.hadoop.store.output.TextFileWriter.close(TextFileWriter.java:92)
at org.springframework.xd.integration.hadoop.outbound.HdfsDataStoreMessageHandler.doStop(HdfsDataStoreMessageHandler.java:58)
at org.springframework.xd.integration.hadoop.outbound.HdfsStoreMessageHandler.stop(HdfsStoreMessageHandler.java:94)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:201)
at com.sun.proxy.$Proxy120.stop(Unknown Source)
at org.springframework.integration.endpoint.EventDrivenConsumer.doStop(EventDrivenConsumer.java:64)
at org.springframework.integration.endpoint.AbstractEndpoint.stop(AbstractEndpoint.java:100)
at org.springframework.integration.endpoint.AbstractEndpoint.stop(AbstractEndpoint.java:115)
at org.springframework.integration.config.ConsumerEndpointFactoryBean.stop(ConsumerEndpointFactoryBean.java:303)
at org.springframework.context.support.DefaultLifecycleProcessor.doStop(DefaultLifecycleProcessor.java:229)
at org.springframework.context.support.DefaultLifecycleProcessor.access$300(DefaultLifecycleProcessor.java:51)
at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.stop(DefaultLifecycleProcessor.java:363)
at org.springframework.context.support.DefaultLifecycleProcessor.stopBeans(DefaultLifecycleProcessor.java:202)
at org.springframework.context.support.DefaultLifecycleProcessor.stop(DefaultLifecycleProcessor.java:106)
at org.springframework.context.support.AbstractApplicationContext.stop(AbstractApplicationContext.java:1186)
at org.springframework.xd.module.core.SimpleModule.stop(SimpleModule.java:234)
at org.springframework.xd.dirt.module.ModuleDeployer.destroyModule(ModuleDeployer.java:132)
at org.springframework.xd.dirt.module.ModuleDeployer.handleUndeploy(ModuleDeployer.java:111)
at org.springframework.xd.dirt.module.ModuleDeployer.undeploy(ModuleDeployer.java:83)
at org.springframework.xd.dirt.server.ContainerRegistrar.undeployModule(ContainerRegistrar.java:261)
at org.springframework.xd.dirt.server.ContainerRegistrar$StreamModuleWatcher.process(ContainerRegistrar.java:884)
at org.apache.curator.framework.imps.NamespaceWatcher.process(NamespaceWatcher.java:67)
at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:522)
at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:498)
Caused by: java.io.FileNotFoundException: Requested file /xd/foo/foo-1.txt does not exist.
at com.mapr.fs.MapRFileSystem.getMapRFileStatus(MapRFileSystem.java:805)
at com.mapr.fs.MapRFileSystem.delete(MapRFileSystem.java:629)
at org.springframework.data.hadoop.store.support.OutputStoreObjectSupport.renameFile(OutputStoreObjectSupport.java:258)
... 29 more

我看了一眼 OutputStoreObjectSupport.renameFile() 功能。当hdfs上的文件完成时，此方法尝试将文件/xd/foo/foo-1.txt.tmp重命名为xd/foo/foo1.txt。这是相关代码：

try {
        FileSystem fs = path.getFileSystem(getConfiguration());

        boolean succeed;
        try {
            fs.delete(toPath, false);
            log.info("Renaming path=[" + path + "] toPath=[" + toPath + "]");
            succeed = fs.rename(path, toPath);
        } catch (Exception e) {
            throw new StoreException("Failed renaming from " + path + " to " + toPath, e);
        }
        if (!succeed) {
            throw new StoreException("Failed renaming from " + path + " to " + toPath + " because hdfs returned false");
        }
    }

当目标文件在hdfs上不存在时，maprfs似乎在 fs.delete(toPath, false) 被称为。但是在这种情况下抛出一个异常是没有意义的。我假设其他文件系统实现的行为不同，但这一点我仍然需要验证。不幸的是，我找不到maprfilesystem.java的源代码。这是封闭源吗？这将有助于我更好地理解这个问题。有人有从springxd到maprfs的写作经验吗？或者用spring-data-hadoop重命名maprfs上的文件？

编辑

我设法用一个简单的测试用例（见下文）在springxd之外重现了这个问题。请注意，只有在设置了inwritingsuffix或inwritingprefix时才会引发此异常。否则springhadoop将不会尝试重命名该文件。所以这对我来说仍然是一个令人不满意的解决方法：不要使用inwritingprefixes和inwritinguffixes。

@ContextConfiguration("context.xml")
@RunWith(SpringJUnit4ClassRunner.class)
public class MaprfsSinkTest {

    @Autowired 
    Configuration configuration;

    @Autowired
    FileSystem filesystem;

    @Autowired 
    DataStoreWriter<String >storeWriter;

    @Test
    public void testRenameOnMaprfs() throws IOException, InterruptedException {
        Path testPath = new Path("/tmp/foo.txt");
        filesystem.delete(testPath, true);
        TextFileWriter writer = new TextFileWriter(configuration, testPath, null);
        writer.setInWritingSuffix("tmp");
        writer.write("some entity");
        writer.close();
    }

    @Test
    public void testStoreWriter() throws IOException {
        this.storeWriter.write("something");
    }

}