apache/hadoop · error · IllegalArgumentException

Read-ahead block size must be positive

Error message

Read-ahead block size must be positive

What it means

Error "Read-ahead block size must be positive" thrown in apache/hadoop.

Source

Thrown at hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/ReadBufferManager.java:221

  /**
   * Gets the block size used for read-ahead operations.
   *
   * @return the read-ahead block size in bytes
   */
  @VisibleForTesting
  protected static int getReadAheadBlockSize() {
    return blockSize;
  }

  /**
   * Sets the block size used for read-ahead operations.
   *
   * @param readAheadBlockSize the read-ahead block size in bytes
   */
  @VisibleForTesting
  protected static void setReadAheadBlockSize(int readAheadBlockSize) {
    if (readAheadBlockSize <= 0) {
      throw new IllegalArgumentException("Read-ahead block size must be positive");
    }
    blockSize = readAheadBlockSize;
  }

  /**
   * Gets the queue of read-ahead requests.
   *
   * @return the queue of {@link ReadBuffer} objects in the read-ahead queue
   */
  Queue<ReadBuffer> getReadAheadQueue() {
    return readAheadQueue;
  }

  /**
   * Gets the list of in-progress read buffers.
   *
   * @return the list of {@link ReadBuffer} objects that are currently being processed
   */

View on GitHub (pinned to 2add963021)

Solutions

1. Set fs.azure.readahead.block.size (or the relevant read-ahead size key) to a positive value.
2. Verify units and parsing of the configured block size.

When it happens

Trigger: ReadBufferManager is initialized with a non-positive read-ahead block size.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/1d9183bed4f2b0f5. Report an issue: GitHub.