apache/druid · error · RuntimeException

Failed to load next batch of results

Error message

Failed to load next batch of results

What it means

The CombiningYielderAdapter-style nextBatch() in ParallelMergeCombiningSequence blocks via ForkJoinPool.managedBlock() waiting for the next ResultBatch from workers. An InterruptedException is wrapped in RuntimeException('Failed to load next batch of results').

Solutions

1. Confirm whether the interruption was a deliberate cancel (check query cancellation logs/scheduler)
2. Retry the query if cancellation was unintended; adjust timeouts otherwise
3. Close the Yielder promptly on failure to release underlying batch yielders

Example fix

// before
while (!yielder.isDone()) { yielder = yielder.next(init); } // interrupted mid-stream
// after
try {
  while (!yielder.isDone()) { yielder = yielder.next(init); }
} catch (RuntimeException e) {
  if (e.getCause() instanceof InterruptedException) { /* cancelled */ }
  yielder.close();
  throw e;
}

try { yielder = yielder.next(init); } catch (RuntimeException e) {
  if (e.getCause() instanceof InterruptedException) { Thread.currentThread().interrupt(); yielder.close(); return; }
  throw e;
}

When it happens

Trigger: Thread interruption while advancing to the next result batch during iteration of a parallel merge combining sequence (after the first batch loaded successfully).

Common situations: Mid-stream query cancellation or timeout; broker or task shutdown while results are still streaming from parallel merge workers.

Understand the failure class

Background: Request timed out: what client-side request timeouts mean across libraries (Request timed out, TIMED_OUT, APITimeoutError) — this error's family across 39 libraries.

Related errors

• Failed to load initial batch of results
• Failed to offer result to output queue
• Exception while waiting to extract distributions.
• Query interrupted
• Stream ingestion task unexpectedly attempted to overwrite…

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/966a747e754740c3. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/java/util/common/guava/ParallelMergeCombiningSequence.java:1024

    BatchedResultsCursor(Ordering<E> ordering)
    {
      this.ordering = ordering;
    }

    public abstract void initialize();

    public abstract void advance();

    public abstract boolean isDone();

    void nextBatch()
    {
      try {
        ForkJoinPool.managedBlock(this);
      }
      catch (InterruptedException e) {
        throw new RuntimeException("Failed to load next batch of results", e);
      }
    }

    @Override
    public void close() throws IOException
    {
      // nothing to close for blocking queue, but yielders will need to clean up or they will leak resources
    }

    public E get()
    {
      return resultBatch.get();
    }

    @Override
    public int compareTo(BatchedResultsCursor<E> o)
    {
      return ordering.compare(get(), o.get());

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