【原創】大叔問題定位分享（17）spark查orc格式數據偶爾報錯NullPointerException

spark查orc格式的數據有時會報這個錯

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

跟進代碼

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.

 

可見hive.exec.orc.split.strategy默認是HYBRID，HYBRID時若是不知足

if (avgFileSize > context.maxSize) {

則

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

報錯的就是BISplitStrategy，具體這個類爲何報錯尚未細看，不過能夠修改設置避免這個問題

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

問題暫時解決，未完待續；