apache/hadoop · warning · IllegalArgumentException

${objectName} is not a valid Hadoop mbean

Error message

${objectName} is not a valid Hadoop mbean

What it means

IllegalArgumentException from MBeans.getMbeanNameService(ObjectName) when the given JMX ObjectName does not match Hadoop's MBean naming pattern '^Hadoop:service=<SERVICE>,name=<NAME>' (MBEAN_NAME_PATTERN). Hadoop registers all its MBeans under the 'Hadoop:' domain with exactly a 'service=' key and a 'name=' key; these helper methods decompose such names and reject anything else. The message prints the offending ObjectName so the mismatch is obvious.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/util/MBeans.java:121

        if (LOG.isTraceEnabled()) {
          LOG.trace("Failed to register MBean \"" + name + "\"", iaee);
        } else {
          LOG.warn("Failed to register MBean \"" + name
              + "\": Instance already exists.");
        }
      } catch (Exception e) {
        LOG.warn("Failed to register MBean \"" + name + "\"", e);
      }
    }
    return null;
  }

  public static String getMbeanNameService(final ObjectName objectName) {
    Matcher matcher = MBEAN_NAME_PATTERN.matcher(objectName.toString());
    if (matcher.matches()) {
      return matcher.group(1);
    } else {
      throw new IllegalArgumentException(
          objectName + " is not a valid Hadoop mbean");
    }
  }

  public static String getMbeanNameName(final ObjectName objectName) {
    Matcher matcher = MBEAN_NAME_PATTERN.matcher(objectName.toString());
    if (matcher.matches()) {
      return matcher.group(2);
    } else {
      throw new IllegalArgumentException(
          objectName + " is not a valid Hadoop mbean");
    }
  }

  static public void unregister(ObjectName mbeanName) {
    LOG.debug("Unregistering "+ mbeanName);
    final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
    if (mbeanName == null) {

View on GitHub (pinned to 2add963021)

Solutions

1. Only call getMbeanNameService/getMbeanNameName on ObjectNames you obtained via MBeans.register() or that you have verified start with 'Hadoop:service=...,name=...'
2. Pre-filter ObjectNames with your own regex or startsWith("Hadoop:service=") check before calling the helper
3. If you register custom beans, use the standard form new ObjectName("Hadoop:service=<svc>,name=<name>") so decomposition works

Example fix

// before
String svc = MBeans.getMbeanNameService(objectName); // objectName = 'java.lang:type=Memory' -> IllegalArgumentException

// after
if (objectName.getDomain().equals("Hadoop")
    && objectName.getKeyPropertyList().size() == 2
    && objectName.getKeyProperty("service") != null
    && objectName.getKeyProperty("name") != null) {
  String svc = MBeans.getMbeanNameService(objectName);
}

private static final Pattern HADOOP_MBEAN =
    Pattern.compile("^Hadoop:service=([^,]+),name=(.+)$");
boolean isHadoopMbean(ObjectName n) { return HADOOP_MBEAN.matcher(n.toString()).matches(); }

static boolean isHadoopMbeanName(ObjectName n) {
  return "Hadoop".equals(n.getDomain())
      && n.getKeyProperty("service") != null
      && n.getKeyProperty("name") != null
      && n.getKeyPropertyList().size() == 2;
}

When it happens

Trigger: Calling getMbeanNameService() with an ObjectName from a non-Hadoop bean (e.g., 'java.lang:type=Memory'), or a Hadoop bean whose name was created with extra keys, missing keys, or a different domain (e.g., 'Hadoop:service=NameNode,name=NameNodeInfo,extra=1').

Common situations: Monitoring/tooling code that iterates all platform MBeans and blindly passes each name to these helpers; refactoring that renames MBeans away from the standard pattern; third-party code registering beans into the Hadoop domain with nonstandard keys.

Related errors

• Wrong length: {digest.length}
• Wrong length: {hex.length}
• Not a hex character: {c}
• No schema options are provided
• No codec option is provided

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/4f6f944efe875066. Report an issue: GitHub.