apache/hadoop · error · IOException

Initialization of all the collectors failed. Error in last c

Error message

Initialization of all the collectors failed. Error in last collector was:{lastException}

What it means

Error "Initialization of all the collectors failed. Error in last collector was:{lastException}" 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:423

          clazz.asSubclass(MapOutputCollector.class);
        LOG.debug("Trying map output collector class: " + subclazz.getName());
        MapOutputCollector<KEY, VALUE> collector =
          ReflectionUtils.newInstance(subclazz, job);
        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());

View on GitHub (pinned to 2add963021)

Solutions

1. Review the reported last exception to fix collector initialization, commonly invalid mapreduce.task.io.sort.mb or spill.percent settings or insufficient memory.

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:423 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/eccf55dc278ab04c. Report an issue: GitHub.