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').

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());

View on GitHub (pinned to 9b90983fd2)

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 offer result to output queue
• Failed to load initial batch of results
• Exception while waiting to extract distributions.
• Transaction failure publishing segments for sequence [%s]
• Stream ingestion task unexpectedly attempted to overwrite se

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