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复制本地文件到HDFS本地测试异常
项目中需要将本地文件拷贝到hdfs上,由于本人比较懒,于是使用擅长的Java程序通过Hadoop.FileSystem.CopyFromLocalFile方法来实现。 在本地(Window 7 环境)本地模式下运行却遇到了下述异常:
An exception or error caused a run to abort: org.apache.hadoop.io.nativeio.NativeIO$Windows.createFileWithMode0(Ljava/lang/String;JJJI)Ljava/io/FileDescriptor; java.lang.UnsatisfiedLinkError: org.apache.hadoop.io.nativeio.NativeIO$Windows.createFileWithMode0(Ljava/lang/String;JJJI)Ljava/io/FileDescriptor; at org.apache.hadoop.io.nativeio.NativeIO$Windows.createFileWithMode0(Native Method) at org.apache.hadoop.io.nativeio.NativeIO$Windows.createFileOutputStreamWithMode(NativeIO.java:559) at org.apache.hadoop.fs.RawLocalFileSystem$LocalFSFileOutputStream.<init>(RawLocalFileSystem.java:219) at org.apache.hadoop.fs.RawLocalFileSystem$LocalFSFileOutputStream.<init>(RawLocalFileSystem.java:209) at org.apache.hadoop.fs.RawLocalFileSystem.createOutputStreamWithMode(RawLocalFileSystem.java:307) at org.apache.hadoop.fs.RawLocalFileSystem.create(RawLocalFileSystem.java:295) at org.apache.hadoop.fs.RawLocalFileSystem.create(RawLocalFileSystem.java:328) at org.apache.hadoop.fs.ChecksumFileSystem$ChecksumFSOutputSummer.<init>(ChecksumFileSystem.java:388) at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:451) at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:430) at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:920) at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:901) at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:798) at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:368) at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:341) at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:292) at org.apache.hadoop.fs.LocalFileSystem.copyFromLocalFile(LocalFileSystem.java:82) at org.apache.hadoop.fs.FileSystem.copyFromLocalFile(FileSystem.java:1882)
通过分析异常堆栈可知,
org.apache.hadoop.io.nativeio.NativeIO$Windows.createFileWithMode0方法发生了异常,createFileWithMode0方法的实现如下:
/** Wrapper around CreateFile() with security descriptor on Windows */ private static native FileDescriptor createFileWithMode0(String path, long desiredAccess, long shareMode, long creationDisposition, int mode) throws NativeIOException;
通过代码可知,这个方法是hadoop不支持的方法。那么为什么会调用这个方法,通过异常堆栈继续向上追踪,
是在 org.apache.hadoop.fs.RawLocalFileSystem$LocalFSFileOutputStream.<init> 过程调用了nativeio.NativeIO$Windows类,对应的方法如下:
1 private LocalFSFileOutputStream(Path f, boolean append, 2 FsPermission permission) throws IOException { 3 File file = pathToFile(f); 4 if (permission == null) { 5 this.fos = new FileOutputStream(file, append); 6 } else { 7 if (Shell.WINDOWS && NativeIO.isAvailable()) { 8 this.fos = NativeIO.Windows.createFileOutputStreamWithMode(file, 9 append, permission.toShort());10 } else {11 this.fos = new FileOutputStream(file, append);12 boolean success = false;13 try {14 setPermission(f, permission);15 success = true;16 } finally {17 if (!success) {18 IOUtils.cleanup(LOG, this.fos);19 }20 }21 }22 }23 }
通过调用椎栈可知是上述代码第8行调用了NativeIO.Windows类。那么if判断应该是成立的,分析NativeIO.isAvailable方法代码如下:
1 /**2 * Return true if the JNI-based native IO extensions are available.3 */4 public static boolean isAvailable() {5 return NativeCodeLoader.isNativeCodeLoaded() && nativeLoaded;6 }
isAvailable方法主要是调用NativeCodeLoader.isNativeCodeLoaded方法
1 static { 2 // Try to load native hadoop library and set fallback flag appropriately 3 if(LOG.isDebugEnabled()) { 4 LOG.debug("Trying to load the custom-built native-hadoop library..."); 5 } 6 try { 7 System.loadLibrary("hadoop"); 8 LOG.debug("Loaded the native-hadoop library"); 9 nativeCodeLoaded = true;10 } catch (Throwable t) {11 // Ignore failure to load12 if(LOG.isDebugEnabled()) {13 LOG.debug("Failed to load native-hadoop with error: " + t);14 LOG.debug("java.library.path=" +15 System.getProperty("java.library.path"));16 }17 }18 19 if (!nativeCodeLoaded) {20 LOG.warn("Unable to load native-hadoop library for your platform... " +21 "using builtin-java classes where applicable");22 }23 }24 25 /**26 * Check if native-hadoop code is loaded for this platform.27 * 28 * @return <code>true</code> if native-hadoop is loaded, 29 * else <code>false</code>30 */31 public static boolean isNativeCodeLoaded() {32 return nativeCodeLoaded;33 }
通过可以看到,isNativeCodeLoaded方法就是返回一个属性值,那么问题出现在什么地方呢?
经过分析NativeCodeLoaded类的静态构造函数,有一个“System.loadLibrary("hadoop")”方法。 是不是这个方法导致的呢?通过在其他同事环境上调试,System.loadLibrary("hadoop") 会异常,从而运行catch部分,但是本人电脑却不会异常,直接继续运行。那么System.loadLibrary方法是什么用途呢,通过分析源码知道,这个方法是加载本地系统和用户的环境变量的。进而分析是因为本人在C:\\Windows\System32目录下有hadoop.dll文件或环境变量Path中配置了%Hadoop_Home%/bin目录而导致的。
简而言之,是因为配置的系统环境变量Path的任意目录下存在hadoop.dll文件,从而被认为这是一个hadoop集群环境,但是hadoop集群又不支持window环境而产生的异常。处理方法也很简单,检查系统环境变量Path下的每一个目录,确保没有hadoop.dll文件即可。
如果是删除系统环境变量Path的某一个目录,需要重启Intellij Idea后ClassLoader类中的usr_paths或sys_paths才会生效。
复制本地文件到HDFS本地测试异常