apache/cassandra · error · RuntimeException

Error reading:

Error message

Error reading: 

What it means

RuntimeException thrown by NodeProbe's thread-pool metric reader when reading the JMX attribute fails (IOException/instance errors while proxying the gauge/counter MBean). It is a wrapper guard: the metric name was recognized but the MBean attribute could not be read from the remote server.

Solutions

1. Retry; transient JMX failures are common under load
2. Verify the thread pool MBean still exists (pool may have been removed)
3. Check JMX connection stability and timeouts

When it happens

Trigger: Thrown at src/java/org/apache/cassandra/tools/NodeProbe.java:2032 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/3f94740710d2d04c. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/tools/NodeProbe.java:2032

          switch (metricName)
          {
              case ThreadPoolMetrics.ACTIVE_TASKS:
              case ThreadPoolMetrics.PENDING_TASKS:
              case ThreadPoolMetrics.COMPLETED_TASKS:
              case ThreadPoolMetrics.CORE_POOL_SIZE:
              case ThreadPoolMetrics.MAX_POOL_SIZE:
              case ThreadPoolMetrics.MAX_TASKS_QUEUED:
                  return JMX.newMBeanProxy(mbeanServerConn, oName, CassandraMetricsRegistry.JmxGaugeMBean.class).getValue();
              case ThreadPoolMetrics.TOTAL_BLOCKED_TASKS:
              case ThreadPoolMetrics.CURRENTLY_BLOCKED_TASKS:
                  return JMX.newMBeanProxy(mbeanServerConn, oName, CassandraMetricsRegistry.JmxCounterMBean.class).getCount();
              default:
                  throw new AssertionError("Unknown ThreadPools metric name " + metricName);
          }
      }
      catch (Exception e)
      {
          throw new RuntimeException("Error reading: " + name, e);
      }
    }

    public Object getSaiMetric(String ks, String cf, String metricName)
    {
        try
        {
            String scope = getSaiMetricScope(metricName);
            String objectNameStr = String.format("org.apache.cassandra.metrics:type=StorageAttachedIndex,keyspace=%s,table=%s,scope=%s,name=%s",ks, cf, scope, metricName);
            ObjectName oName = new ObjectName(objectNameStr);

            Set<ObjectName> matchingMBeans = mbeanServerConn.queryNames(oName, null);
            if (matchingMBeans.isEmpty())
                return null;

            return getSaiMetricValue(metricName, oName);
        }
        catch (MalformedObjectNameException e)

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