java - 用MiniDFSCluster对hadoop hdfs写的进行单元测试

Question

我编写了一个写入 hadoop HDFS 的类。我使用的是 1.2.1 版的 hadoop jar。

我想测试这门课。所以基于博客如this one我写了我的代码:

private void createSimulatedHdfs() {
    conf = new Configuration();
    // 100K blocksize
    conf.setLong(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, 1024 * 100);
    conf.setLong(DFSConfigKeys.DFS_BLOCK_SIZE_KEY, 100);
    conf.setInt(DFSConfigKeys.DFS_BYTES_PER_CHECKSUM_KEY, 1);
    conf.setLong(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY, DFS_REPLICATION_INTERVAL);
    conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_INTERVAL_KEY, DFS_REPLICATION_INTERVAL);

    try {
        // simulated HDFS
        cluster = new MiniDFSCluster(conf, DATANODE_COUNT, true, null);
        cluster.waitActive();
        simulatedHdfs = cluster.getFileSystem();
    } catch (IOException e) {
        Assert.fail("Could not create simulated HDFS " + e.getMessage());
    }
    }

但是在运行新的 MiniDFSCluster 时遇到异常:

java.lang.AssertionError: Could not create simulated HDFS Cannot run program "du": CreateProcess error=2, The system cannot find the file specified
    at org.junit.Assert.fail(Assert.java:88)
    at com.taptica.hdfs.writer.HdfsWriterUTest.createSimulatedHdfs(HdfsWriterUTest.java:101)
    at com.taptica.hdfs.writer.HdfsWriterUTest.initJunitModeTest(HdfsWriterUTest.java:42)
    at com.taptica.hdfs.writer.HdfsWriterUTest.writeTest(HdfsWriterUTest.java:50)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

我没有在我的本地环境中安装 hadoop(我也不打算这样做)。我怎样才能克服这个问题？

Answer 1

对于 JUnit 测试，无需安装 Hadoop 和第三方实用程序即可使用本地文件系统:

        LocalFileSystem fs = FileSystem.getLocal(new Configuration());

另请查看 MUnit，这是一个对 MR 测试很有帮助的实用程序:http://mrunit.apache.org/