【原创】大叔问题定位分享（17）spark查orc格式数据偶尔报错NullPointerException

spark查orc格式的数据有时会报这个错

Caused by: java.lang.NullPointerException
at org.apache.hadoop.hive.ql.io.orc.OrcInputFormat$BISplitStrategy.getSplits(OrcInputFormat.java:560)
at org.apache.hadoop.hive.ql.io.orc.OrcInputFormat.generateSplitsInfo(OrcInputFormat.java:1010)
... 47 more

跟进代码

org.apache.hadoop.hive.ql.io.orc.OrcInputFormat

  static enum SplitStrategyKind {
    HYBRID,
    BI,
    ETL
  }
...

    Context(Configuration conf) {
      this.conf = conf;
      minSize = conf.getLong(MIN_SPLIT_SIZE, DEFAULT_MIN_SPLIT_SIZE);
      maxSize = conf.getLong(MAX_SPLIT_SIZE, DEFAULT_MAX_SPLIT_SIZE);
      String ss = conf.get(ConfVars.HIVE_ORC_SPLIT_STRATEGY.varname);
      if (ss == null || ss.equals(SplitStrategyKind.HYBRID.name())) {
        splitStrategyKind = SplitStrategyKind.HYBRID;
      } else {
        LOG.info("Enforcing " + ss + " ORC split strategy");
        splitStrategyKind = SplitStrategyKind.valueOf(ss);
      }

...
        switch(context.splitStrategyKind) {
          case BI:
            // BI strategy requested through config
            splitStrategy = new BISplitStrategy(context, fs, dir, children, isOriginal,
                deltas, covered);
            break;
          case ETL:
            // ETL strategy requested through config
            splitStrategy = new ETLSplitStrategy(context, fs, dir, children, isOriginal,
                deltas, covered);
            break;
          default:
            // HYBRID strategy
            if (avgFileSize > context.maxSize) {
              splitStrategy = new ETLSplitStrategy(context, fs, dir, children, isOriginal, deltas,
                  covered);
            } else {
              splitStrategy = new BISplitStrategy(context, fs, dir, children, isOriginal, deltas,
                  covered);
            }
            break;
        }

org.apache.hadoop.hive.conf.HiveConf.ConfVars

    HIVE_ORC_SPLIT_STRATEGY("hive.exec.orc.split.strategy", "HYBRID", new StringSet("HYBRID", "BI", "ETL"),
        "This is not a user level config. BI strategy is used when the requirement is to spend less time in split generation" +
        " as opposed to query execution (split generation does not read or cache file footers)." +
        " ETL strategy is used when spending little more time in split generation is acceptable" +
        " (split generation reads and caches file footers). HYBRID chooses between the above strategies" +
        " based on heuristics."),

The HYBRID mode reads the footers for all files if there are fewer files than expected mapper count, switching over to generating 1 split per file if the average file sizes are smaller than the default HDFS blocksize. ETL strategy always reads the ORC footers before generating splits, while the BI strategy generates per-file splits fast without reading any data from HDFS.

可见hive.exec.orc.split.strategy默认是HYBRID，HYBRID时如果不满足

if (avgFileSize > context.maxSize) {

则

splitStrategy = new BISplitStrategy(context, fs, dir, children, isOriginal, deltas,
covered);

报错的就是BISplitStrategy，具体这个类为什么报错还没有细看，不过可以修改设置避免这个问题

set hive.exec.orc.split.strategy=ETL

问题暂时解决，未完待续；