apache/hadoop · error · IOException

Invalid/missing generation bytes: {}

Error message

Invalid/missing generation bytes: {}

What it means

Error "Invalid/missing generation bytes: {}" thrown in apache/hadoop.

Source

Thrown at hadoop-tools/hadoop-gridmix/src/main/java/org/apache/hadoop/mapred/gridmix/GenerateData.java:245

        r.nextBytes(val.getBytes());
        val.setSize((int)Math.min(val.getLength(), bytes));
        context.write(key, val);
      }
    }

  }

  static class GenDataFormat extends InputFormat<NullWritable,LongWritable> {

    @Override
    public List<InputSplit> getSplits(JobContext jobCtxt) throws IOException {
      final JobClient client =
        new JobClient(new JobConf(jobCtxt.getConfiguration()));
      ClusterStatus stat = client.getClusterStatus(true);
      final long toGen =
        jobCtxt.getConfiguration().getLong(GRIDMIX_GEN_BYTES, -1);
      if (toGen < 0) {
        throw new IOException("Invalid/missing generation bytes: " + toGen);
      }
      final int nTrackers = stat.getTaskTrackers();
      final long bytesPerTracker = toGen / nTrackers;
      final ArrayList<InputSplit> splits = new ArrayList<InputSplit>(nTrackers);
      final Pattern trackerPattern = Pattern.compile("tracker_([^:]*):.*");
      final Matcher m = trackerPattern.matcher("");
      for (String tracker : stat.getActiveTrackerNames()) {
        m.reset(tracker);
        if (!m.find()) {
          System.err.println("Skipping node: " + tracker);
          continue;
        }
        final String name = m.group(1);
        splits.add(new GenSplit(bytesPerTracker, new String[] { name }));
      }
      return splits;
    }

View on GitHub (pinned to 2add963021)

Solutions

1. Pass a valid positive byte count via -generate <size> (e.g. -generate 100GB).

When it happens

Trigger: The gridmix.generate.file.size (or related generation byte count) configured for Gridmix data generation is missing or invalid.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/4fc58951aca684b9. Report an issue: GitHub.