apache/hadoop · error · IOException

Invalid request Map Id = {mapId} Reducer = {reduce} Index I

Error message

Invalid request  Map Id = {mapId} Reducer = {reduce} Index Info Length = {info.mapSpillRecord.size()}

What it means

Error "Invalid request Map Id = {mapId} Reducer = {reduce} Index Info Length = {info.mapSpillRecord.size()}" thrown in apache/hadoop.

Source

Thrown at hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/IndexCache.java:84

    if (info == null) {
      info = readIndexFileToCache(fileName, mapId, expectedIndexOwner);
    } else {
      synchronized(info) {
        while (isUnderConstruction(info)) {
          try {
            info.wait();
          } catch (InterruptedException e) {
            throw new IOException("Interrupted waiting for construction", e);
          }
        }
      }
      LOG.debug("IndexCache HIT: MapId " + mapId + " found");
    }

    if (info.mapSpillRecord.size() == 0 ||
        info.mapSpillRecord.size() <= reduce) {
      throw new IOException("Invalid request " +
        " Map Id = " + mapId + " Reducer = " + reduce +
        " Index Info Length = " + info.mapSpillRecord.size());
    }
    return info.mapSpillRecord.getIndex(reduce);
  }

  private boolean isUnderConstruction(IndexInformation info) {
    synchronized(info) {
      return (null == info.mapSpillRecord);
    }
  }

  private IndexInformation readIndexFileToCache(Path indexFileName,
                                                String mapId,
                                                String expectedIndexOwner)
    throws IOException {
    IndexInformation info;
    IndexInformation newInd = new IndexInformation();

View on GitHub (pinned to 2add963021)

Solutions

1. The requested map output index entry exceeds the cached spill record; verify the shuffle request references a valid mapId/reduce pair and regenerate the index by rerunning the map task.

When it happens

Trigger: Thrown at hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/IndexCache.java:84 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/a2e1131bbb09ac59. Report an issue: GitHub.