- 异常完整描述
Exception in thread "main" java.lang.UnsatisfiedLinkError:org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z
- 异常追踪信息如下:
java.lang.UnsatisfiedLinkError: org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z
at org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Native Method)
at org.apache.hadoop.io.nativeio.NativeIO$Windows.access(NativeIO.java:609)
at org.apache.hadoop.fs.FileUtil.canRead(FileUtil.java:980)
at org.apache.hadoop.util.DiskChecker.checkAccessByFileMethods(DiskChecker.java:187)
at org.apache.hadoop.util.DiskChecker.checkDirAccess(DiskChecker.java:174)
at org.apache.hadoop.util.DiskChecker.checkDir(DiskChecker.java:108)
at org.apache.hadoop.fs.LocalDirAllocator$AllocatorPerContext.confChanged(LocalDirAllocator.java:314)
at org.apache.hadoop.fs.LocalDirAllocator$AllocatorPerContext.getLocalPathForWrite(LocalDirAllocator.java:377)
at org.apache.hadoop.fs.LocalDirAllocator.getLocalPathForWrite(LocalDirAllocator.java:151)
at org.apache.hadoop.fs.LocalDirAllocator.getLocalPathForWrite(LocalDirAllocator.java:132)
at org.apache.hadoop.fs.LocalDirAllocator.getLocalPathForWrite(LocalDirAllocator.java:116)
at org.apache.hadoop.mapred.LocalDistributedCacheManager.setup(LocalDistributedCacheManager.java:125)
at org.apache.hadoop.mapred.LocalJobRunner$Job.<init>(LocalJobRunner.java:171)
at org.apache.hadoop.mapred.LocalJobRunner.submitJob(LocalJobRunner.java:758)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:244)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1307)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1304)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1920)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:1304)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1325)
……
- 该异常常见于windows环境中进行hadoop本地调试的场景
通过追踪信息可以找到问题发生源是由于NativeIO.java:609的access报错,代码如下:
/**
* Checks whether the current process has desired access rights on
* the given path.
*
* Longer term this native function can be substituted with JDK7
* function Files#isReadable, isWritable, isExecutable.
*
* @param path input path
* @param desiredAccess ACCESS_READ, ACCESS_WRITE or ACCESS_EXECUTE
* @return true if access is allowed
* @throws IOException I/O exception on error
*/
public static boolean access(String path, AccessRight desiredAccess)
throws IOException {
return access0(path, desiredAccess.accessRight());
}
可以看出是通过系统内核判断是否具有操作权限的判断功能,由于windows本身的权限设置此方法常会抛出异常。
- 解决方法1:临时测试修改源码
找到NativeIO的源码,在测试工程内建立同路径文件,复制全部代码,修改access方法如下所示:
public static boolean access(String path, AccessRight desiredAccess)
throws IOException {
return true;
//return access0(path, desiredAccess.accessRight());
}
通过设置恒允许来跳过该问题。
- 解决方法2:使用远程linux集群协助调试
由于问题发生源是windows的关系,只需借助远程linux环境下的(或配置好的windows 环境)hadoop集群进行远程调试即可。
解决方法即为将远程环境的hadoop配置文件(如下)加入调试工程的环境变量中。
- core-site.xml
- hdfs-site.xml
- yarn-site.xml (非任务调试可无)
- mapred-site.xml (一般可无)