apache/hadoop · error · IOException

Unable to retrieve JMX: {}

Error message

Unable to retrieve JMX: {}

What it means

Error "Unable to retrieve JMX: {}" thrown in apache/hadoop.

Source

Thrown at hadoop-tools/hadoop-dynamometer/hadoop-dynamometer-infra/src/main/java/org/apache/hadoop/tools/dynamometer/DynoInfraUtils.java:553

   * @param jmxBeanQuery The JMX bean query to execute; should return a
   *                     JMX property matching {@code jmxProperty}.
   * @param property The name of the JMX property whose value should be polled.
   * @return The value associated with the property.
   */
  static String fetchNameNodeJMXValue(Properties nameNodeProperties,
      String jmxBeanQuery, String property) throws IOException {
    URI nnWebUri = getNameNodeWebUri(nameNodeProperties);
    URL queryURL;
    try {
      queryURL = new URL(nnWebUri.getScheme(), nnWebUri.getHost(),
          nnWebUri.getPort(), "/jmx?qry=" + jmxBeanQuery);
    } catch (MalformedURLException e) {
      throw new IllegalArgumentException("Invalid JMX query: \"" + jmxBeanQuery
          + "\" against " + "NameNode URI: " + nnWebUri);
    }
    HttpURLConnection conn = (HttpURLConnection) queryURL.openConnection();
    if (conn.getResponseCode() != 200) {
      throw new IOException(
          "Unable to retrieve JMX: " + conn.getResponseMessage());
    }
    InputStream in = conn.getInputStream();
    JsonFactory fac = new JsonFactory();
    JsonParser parser = fac.createParser(in);
    if (parser.nextToken() != JsonToken.START_OBJECT
        || parser.nextToken() != JsonToken.FIELD_NAME
        || !parser.getCurrentName().equals("beans")
        || parser.nextToken() != JsonToken.START_ARRAY
        || parser.nextToken() != JsonToken.START_OBJECT) {
      throw new IOException(
          "Unexpected format of JMX JSON response for: " + jmxBeanQuery);
    }
    int objectDepth = 1;
    String ret = null;
    while (objectDepth > 0) {
      JsonToken tok = parser.nextToken();
      if (tok == JsonToken.START_OBJECT) {

View on GitHub (pinned to 2add963021)

Solutions

1. Confirm the NameNode JMX servlet (usually /jmx) is reachable from the dynamometer host and that authentication succeeds.

When it happens

Trigger: The HTTP request to the NameNode /jmx endpoint fails (connection refused, timeout, or non-OK status), so the JMX properties cannot be retrieved.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/67f3bbb3e9984689. Report an issue: GitHub.