apache/hadoop · error · IOException

Initialization of all the collectors failed.

Error message

Initialization of all the collectors failed.

What it means

Error "Initialization of all the collectors failed." thrown in apache/hadoop.

Source

Thrown at hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java:427

        collector.init(context);
        LOG.info("Map output collector class = " + collector.getClass().getName());
        return collector;
      } catch (Exception e) {
        String msg = "Unable to initialize MapOutputCollector " + clazz.getName();
        if (--remainingCollectors > 0) {
          msg += " (" + remainingCollectors + " more collector(s) to try)";
        }
        lastException = e;
        LOG.warn(msg, e);
      }
    }

    if (lastException != null) {
      throw new IOException("Initialization of all the collectors failed. " +
          "Error in last collector was:" + lastException.toString(),
          lastException);
    } else {
      throw new IOException("Initialization of all the collectors failed.");
    }
  }

  @SuppressWarnings("unchecked")
  private <INKEY,INVALUE,OUTKEY,OUTVALUE>
  void runOldMapper(final JobConf job,
                    final TaskSplitIndex splitIndex,
                    final TaskUmbilicalProtocol umbilical,
                    TaskReporter reporter
                    ) throws IOException, InterruptedException,
                             ClassNotFoundException {
    InputSplit inputSplit = getSplitDetails(new Path(splitIndex.getSplitLocation()),
           splitIndex.getStartOffset());

    updateJobWithSplit(job, inputSplit);
    reporter.setInputSplit(inputSplit);

    RecordReader<INKEY,INVALUE> in = isSkipping() ? 

View on GitHub (pinned to 2add963021)

Solutions

1. Fix the map output collector configuration (io.sort.mb, spill.percent, collector class) and ensure adequate task memory, then rerun the task.

When it happens

Trigger: Thrown at hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java:427 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/f1cf9f478637b7f7. Report an issue: GitHub.