oozie 调度异常 JA009: Filesystem closed

     最近几天发现oozie调度的任务经常会被挂起(SUSPENDED), 之前也存在被挂起的情况，但频率很低， 一周也就一两次， 出现问题时由监控脚本重跑，也不影响正常业务，但最近一两天被挂起的非常频繁，甚至一天有3，4个小时的任务被挂起， 影响正常业务.
      个人猜测跟hadoop集群状态(稳定性)有一定关系，但咨询hadoop运维人员后得知集群近几天并未做改动，也没异常。
    被挂起任务截图:

 
   
   注: loadFlash是一个hive节点，是把flash日志load到hive中, 在这里出现异常，状态变成
    START_MANUAL， 点开loadFlash结点, 如下图:

 
     
     从Error Code和Error Message可以看出，此action出现JA009 Filesystem closed异常
为了定位该问题，先来看看oozie日志吧，来到oozie安装目录， 找到oozie.log日志文件, 搜索 JA009: Filesystem closed 信息，果然，有很多该异常信息

org.apache.oozie.action.ActionExecutorException: JA009: Filesystem closed
    at org.apache.oozie.action.ActionExecutor.convertException(ActionExecutor.java:361)
    at org.apache.oozie.action.hadoop.JavaActionExecutor.prepareActionDir(JavaActionExecutor.java:390)
    at org.apache.oozie.action.hadoop.JavaActionExecutor.start(JavaActionExecutor.java:636)
    at org.apache.oozie.command.wf.ActionStartCommand.call(ActionStartCommand.java:128)
    at org.apache.oozie.command.wf.ActionStartCommand.execute(ActionStartCommand.java:249)
    at org.apache.oozie.command.wf.ActionStartCommand.execute(ActionStartCommand.java:47)
    at org.apache.oozie.command.Command.call(Command.java:202)
    at org.apache.oozie.service.CallableQueueService$CompositeCallable.call(CallableQueueService.java:211)
    at org.apache.oozie.service.CallableQueueService$CallableWrapper.run(CallableQueueService.java:128)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:662)
Caused by: java.io.IOException: Filesystem closed
    at org.apache.hadoop.hdfs.DFSClient.checkOpen(DFSClient.java:232)
    at org.apache.hadoop.hdfs.DFSClient.delete(DFSClient.java:648)
    at org.apache.hadoop.hdfs.DistributedFileSystem.delete(DistributedFileSystem.java:255)
    at org.apache.oozie.action.hadoop.JavaActionExecutor.prepareActionDir(JavaActionExecutor.java:383)
    ... 10 more

      有了该异常信息， 定位问题方便多了， 将ooize源码工程导入eclipse, 找到 JavaActionExecutor.java文件，定位到 prepareActionDir方法:

void prepareActionDir(FileSystem actionFs, Context context) throws ActionExecutorException {
        try {
            Path actionDir = context.getActionDir();
            Path tempActionDir = new Path(actionDir.getParent(), actionDir.getName() + ".tmp");
            if (!actionFs.exists(actionDir)) {
                try {
                    actionFs.copyFromLocalFile(new Path(getOozieRuntimeDir(), getLauncherJarName()), new Path(
                            tempActionDir, getLauncherJarName()));
                    actionFs.rename(tempActionDir, actionDir);
                }
                catch (IOException ex) {
                    actionFs.delete(tempActionDir, true);
                    actionFs.delete(actionDir, true);
                    throw ex;
                }
            }
        }
        catch (Exception ex) {
            throw convertException(ex);
        }
    }

     从prepareActionDir 方法可以看出， 在使用actionFs的时候有可能会出现Filesystem closed异常（如果拿到的这个actionFs已经关闭自然就会抛出异常了）
接下来看看prepareActionDir 方法中FileSystem actionFs参数是如何传入的，找到调用prepareActionDir 的方法:

@Override
   public void start(Context context, WorkflowAction action) throws ActionExecutorException {
       try {
           XLog.getLog(getClass()).debug("Starting action " + action.getId() + " getting Action File System");
           FileSystem actionFs = getActionFileSystem(context, action);
           XLog.getLog(getClass()).debug("Preparing action Dir through copying " + context.getActionDir());
           prepareActionDir(actionFs, context);
           XLog.getLog(getClass()).debug("Action Dir is ready. Submitting the action ");
           submitLauncher(context, action);
           XLog.getLog(getClass()).debug("Action submit completed. Performing check ");
           check(context, action);
           XLog.getLog(getClass()).debug("Action check is done after submission");
       }
       catch (Exception ex) {
           throw convertException(ex);
       }
   }

     通过FileSystem actionFs = getActionFileSystem(context, action);代码可知，actionFs 是通过getActionFileSystem方法获取的， 再来看getActionFileSystem方法:

protected FileSystem getActionFileSystem(Context context, Element actionXml) throws ActionExecutorException {
        try {
            return context.getAppFileSystem();
        }
        catch (Exception ex) {
            throw convertException(ex);
        }
    }

public FileSystem getAppFileSystem() throws HadoopAccessorException, IOException, URISyntaxException {
           WorkflowJob workflow = getWorkflow();
           XConfiguration jobConf = new XConfiguration(new StringReader(workflow.getConf()));
           Configuration fsConf = new Configuration();
           XConfiguration.copy(jobConf, fsConf);
           return Services.get().get(HadoopAccessorService.class).createFileSystem(workflow.getUser(),
                   workflow.getGroup(), new URI(getWorkflow().getAppPath()), fsConf);

       }

     至此终于找到actionFs是通过HadoopAccessorService来获取的,看看HadoopAccessorService的createFileSystem方法:

public FileSystem createFileSystem(String user, String group, URI uri, Configuration conf)
           throws HadoopAccessorException {
       validateNameNode(uri.getAuthority());
       conf = createConfiguration(user, group, conf);
       try {
           return FileSystem.get(uri, conf);
       }
       catch (IOException e) {
           throw new HadoopAccessorException(ErrorCode.E0902, e);
       }
   }

     真相大白，oozie通过调用hadoop的FileSystem.get(uri, conf);  方法来得到FileSystem.
接着看FileSystem.get(uri, conf)源码:

public static FileSystem get(URI uri, Configuration conf) throws IOException {
    String scheme = uri.getScheme();
    String authority = uri.getAuthority();

    if (scheme == null) {                       // no scheme: use default FS
      return get(conf);
    }

    if (authority == null) {                       // no authority
      URI defaultUri = getDefaultUri(conf);
      if (scheme.equals(defaultUri.getScheme())    // if scheme matches default
          && defaultUri.getAuthority() != null) {  // & default has authority
        return get(defaultUri, conf);              // return default
      }
    }

    String disableCacheName = String.format("fs.%s.impl.disable.cache", scheme);
    if (conf.getBoolean(disableCacheName, false)) {
      return createFileSystem(uri, conf);
    }

    return CACHE.get(uri, conf);  // 有缓存哦
  }

      FileSystem.get(uri, conf)方法会根据conf.getBoolean(disableCacheName, false)的值决定是创建FileSystem还是从cache中获取FileSystem, 而默认情况下conf.getBoolean(disableCacheName, false)值为flase(除非特别指定disableCacheName 值为true), 即从cache获取. 问题正是出在这里，我们的oozie作业是小时任务，并由多个action节点组成，每个action节点执行时从cache中获取FileSystem, 有可能该FileSystem因为网络原因或者其他原因已经被closed, 但仍旧被cache, 导致拿到该FileSystem的action在使用时发生IOException异常.
      定位到问题原因后就需要设法改进，方法也很简单，只要使conf.getBoolean(disableCacheName, false)   为true即可，这样每次都会重新创建一个FileSystem, 也就不会从cache中拿到失效的FileSystem了.
     在oozie的workflow里进行如下配置:

<configuration>
 <name>oozie.launcher.fs.hdfs.impl.disable.cachename>
      <value>truevalue>
    property>
  configuration>

   另外从源代码中发现oozie对action节点调度过程中的瞬态错误会有重试机制，默认状态下是3次，我在提交作业时修改成10次

oozie.wf.action.max.retries=10

经过上述修改后， oozie调度健壮性得到了提升^_^

转载于:https://blog.51cto.com/yaoyinjie/762342