Exception occurred updating coordinatorWriteLatency metric

Error message

Exception occurred updating coordinatorWriteLatency metric

What it means

After completing a write, StorageProxy updates the coordinatorWriteLatency latency metric. Any exception thrown while recording that metric (timing, histogram registration, etc.) is caught and logged at warn level — the write itself already succeeded, so this only indicates a metrics-infrastructure problem, not data loss.

Solutions

Read the attached exception stack trace in the log to identify the actual cause
Verify the metrics registry/JMX reporting configuration is valid
Upgrade to a version where the specific metrics bug (if any) is fixed — include the stack trace in a report if reproducible
Confirm writes are succeeding (check write latency/throughput metrics); this warning alone does not affect data

Defensive patterns

Strategy: try-catch

Try / catch

// the library already catches it; treat as noisy-log signal only
if (logsContain("Exception occurred updating coordinatorWriteLatency metric"))
    alertOnMetricsPipeline(); // investigate metrics/JMX infra, not writes

Prevention

Keep Dropwizard/JMX registry configuration valid and tested
Alert on this log pattern to catch metrics-infrastructure regressions early
Confirm write SLOs independently of metric recording

When it happens

Trigger: An Exception escapes the metric update code in the write-completion path (e.g. during coordinatorWriteLatency latency recording), caught by the catch block that logs this message with the stack trace as the argument.

Common situations: Metrics library (Dropwizard) issues; unexpected nulls or races in the latency-recording path; usually seen in logs alongside JMX/metrics registry problems.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/82d5cceb5609dd26. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/service/StorageProxy.java:1640

                    ColumnFamilyStore store = keyspace.getColumnFamilyStore(tableId);
                    if (firstColumnFamilyStore == null)
                    {
                        store.metric.coordinatorWriteLatency.update(latency, NANOSECONDS);
                        firstColumnFamilyStore = store;
                    }
                    else if (!firstColumnFamilyStore.equals(store))
                    {
                        if (uniqueColumnFamilyStores == null)
                            uniqueColumnFamilyStores = new HashSet<>();
                        if (uniqueColumnFamilyStores.add(store))
                            store.metric.coordinatorWriteLatency.update(latency, NANOSECONDS);
                    }
                }
            }
        }
        catch (Exception ex)
        {
            logger.warn("Exception occurred updating coordinatorWriteLatency metric", ex);
        }
    }

    private static void syncWriteToBatchlog(Collection<Mutation> mutations, ReplicaPlan.ForWrite replicaPlan, TimeUUID uuid, Dispatcher.RequestTime requestTime)
    throws WriteTimeoutException, WriteFailureException
    {
        WriteResponseHandler<?> handler = new WriteResponseHandler<>(replicaPlan,
                                                                     WriteType.BATCH_LOG,
                                                                     null,
                                                                     requestTime);

        Batch batch = Batch.createLocal(uuid, FBUtilities.timestampMicros(), mutations);
        Message<Batch> message = Message.out(BATCH_STORE_REQ, batch);
        for (Replica replica : replicaPlan.liveAndDown())
        {
            if (logger.isTraceEnabled())
                logger.trace("Sending batchlog store request {} to {} for {} mutations", batch.id, replica, batch.size());

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