apache/cassandra · error · RuntimeException

No readable value attribute for CQL metric:

Error message

No readable value attribute for CQL metric: 

What it means

RuntimeException thrown by NodeProbe.getCQLMetric when no readable value attribute is found on the CQL metrics MBean for the given metric name. The MBean exists under org.apache.cassandra.metrics:type=CQL but exposes no attribute the code can read a value from — the metric name is wrong or the metric type exposes no scalar attribute.

Solutions

1. Check the exact metric name with nodetool or JConsole under org.apache.cassandra.metrics:type=CQL
2. Use a metric name that maps to a gauge/counter attribute
3. Handle the returned exception in nodetool callers by validating metric names first

When it happens

Trigger: Thrown at src/java/org/apache/cassandra/tools/NodeProbe.java:1965 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/172c484bac874986. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/tools/NodeProbe.java:1965

    }

    /**
     * Retrieve a CQL metric value by name. Works generically for any metric registered under
     * {@code org.apache.cassandra.metrics:type=CQL,name=<metricName>} by inspecting the MBean
     * attributes at runtime, without requiring knowledge of the underlying metric type.
     */
    public Object getCQLMetric(String metricName)
    {
        try
        {
            ObjectName objectName = new ObjectName(DefaultNameFactory.GROUP_NAME + ":type=" + CQLMetrics.TYPE_NAME + ",name=" + metricName);
            for (MBeanAttributeInfo attr : mbeanServerConn.getMBeanInfo(objectName).getAttributes())
            {
                String name = attr.getName();
                if ("Value".equals(name) || "Count".equals(name))
                    return mbeanServerConn.getAttribute(objectName, name);
            }
            throw new RuntimeException("No readable value attribute for CQL metric: " + metricName);
        }
        catch (MalformedObjectNameException | InstanceNotFoundException | IntrospectionException |
               ReflectionException | AttributeNotFoundException | MBeanException | IOException e)
        {
            throw new RuntimeException(e);
        }
    }

    private static Multimap<String, String> getJmxThreadPools(MBeanServerConnection mbeanServerConn)
    {
        try
        {
            Multimap<String, String> threadPools = HashMultimap.create();

            Set<ObjectName> threadPoolObjectNames = mbeanServerConn.queryNames(
                    new ObjectName("org.apache.cassandra.metrics:type=ThreadPools,*"),
                    null);

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