跑tez任务报：Previous writer likely failed to write hdfs://xx, Failing because I am unlikely to write too

报这个错有点坑， hive并没把真实的异常错误信息输出，而是返回一个笼统的错`Previous writer likely failed to write hdfs://xx, Failing because I am unlikely to write too`。源码如下：
```
public LocalResource localizeResource(
      Path src, Path dest, LocalResourceType type, Configuration conf) throws IOException {
    FileSystem destFS = dest.getFileSystem(conf);
    // We call copyFromLocal below, so we basically assume src is a local file.
    FileSystem srcFs = FileSystem.getLocal(conf);
    if (src != null && !checkPreExisting(srcFs, src, dest, conf)) {
      // copy the src to the destination and create local resource.
      // do not overwrite.
      String srcStr = src.toString();
      LOG.info("Localizing resource because it does not exist: " + srcStr + " to dest: " + dest);
      Object notifierNew = new Object(),
          notifierOld = copyNotifiers.putIfAbsent(srcStr, notifierNew),
          notifier = (notifierOld == null) ? notifierNew : notifierOld;
      // To avoid timing issues with notifications (and given that HDFS check is anyway the
      // authoritative one), don't wait infinitely for the notifier, just wait a little bit
      // and check HDFS before and after.
      if (notifierOld != null
          && checkOrWaitForTheFile(srcFs, src, dest, conf, notifierOld, 1, 150, false)) {
        return createLocalResource(destFS, dest, type, LocalResourceVisibility.PRIVATE);
      }
      try {
        destFS.copyFromLocalFile(false, false, src, dest);
        synchronized (notifier) {
          notifier.notifyAll(); // Notify if we have successfully copied the file.
        }
        copyNotifiers.remove(srcStr, notifier);
      } catch (IOException e) {
        if ("Exception while contacting value generator".equals(e.getMessage())) {
          // HADOOP-13155, fixed version: 2.8.0, 3.0.0-alpha1
          throw new IOException("copyFromLocalFile failed due to HDFS KMS failure", e);
        }

LOG.info("Looks like another thread or process is writing the same file");
        int waitAttempts = HiveConf.getIntVar(
            conf, ConfVars.HIVE_LOCALIZE_RESOURCE_NUM_WAIT_ATTEMPTS);
        long sleepInterval = HiveConf.getTimeVar(
            conf, HiveConf.ConfVars.HIVE_LOCALIZE_RESOURCE_WAIT_INTERVAL, TimeUnit.MILLISECONDS);
        // Only log on the first wait, and check after wait on the last iteration.
        if (!checkOrWaitForTheFile(
            srcFs, src, dest, conf, notifierOld, waitAttempts, sleepInterval, true)) {
          LOG.error("Could not find the jar that was being uploaded");
          throw new IOException("Previous writer likely failed to write " + dest +
              ". Failing because I am unlikely to write too.");
        }
      } finally {
        if (notifier == notifierNew) {
          copyNotifiers.remove(srcStr, notifierNew);
        }
      }
    }
    return createLocalResource(destFS, dest, type,
        LocalResourceVisibility.PRIVATE);
  }
```
由于tez要加载的第三方是放在本地，如果有多个HiveServer2的实例，比较容易漏掉哪个服务器忘记放第三方包。如果确认不是包的问题，则需要调试跟踪下
最好的解决方法是调试跟进去看异常信息

阿川CH