apache/pulsar · error · RuntimeException

Error starting LogTopic Producer for function %s

Error message

Error starting LogTopic Producer for function %s

What it means

LogAppender.start() creates a Pulsar Producer bound to the function's log topic (batched, LZ4-compressed). If producer creation throws for any reason (broker unreachable, authorization, topic issues, client config), the appender wraps it in a RuntimeException naming the function FQN, preserving the cause.

Source

Thrown at pulsar-functions/instance/src/main/java/org/apache/pulsar/functions/instance/LogAppender.java:123

    @Override
    public void initialize() {
        this.state = State.INITIALIZED;
    }

    @Override
    public void start() {
        this.state = State.STARTING;
        try {
            producer = pulsarClient.newProducer()
                    .topic(logTopic)
                    .blockIfQueueFull(false)
                    .enableBatching(true)
                    .compressionType(CompressionType.LZ4)
                    .batchingMaxPublishDelay(100, TimeUnit.MILLISECONDS)
                    .property("function", fqn)
                    .create();
        } catch (Exception e) {
            throw new RuntimeException("Error starting LogTopic Producer for function " + fqn, e);
        }
        this.state = State.STARTED;
    }

    @Override
    public void stop() {
        this.state = State.STOPPING;
        if (producer != null) {
            producer.closeAsync();
            producer = null;
        }
        this.state = State.STOPPED;
    }

    @Override
    public boolean isStarted() {
        return state == State.STARTED;
    }

View on GitHub (pinned to 820761864e)

Solutions

1. Read the wrapped cause (e) in the stack trace — fix the underlying producer error (connectivity, auth, topic)
2. Verify the function's logTopic configuration points to a valid topic on the correct cluster/serviceUrl
3. Grant the function's role produce permissions on the log topic namespace (grant permissions on the namespace/topic)
4. Enable topic auto-creation or create the log topic manually; check broker reachability and TLS/auth settings from the function instance

Example fix

// before (conf/worker or function config)
logTopic: persistent://public/default/does-not-exist
// after
logTopic: persistent://public/default/functions-logs
# and grant produce rights:
# pulsar-admin namespaces grant-permissions public/default --role functions-role --actions produce

try { logAppender.start(); }
catch (RuntimeException e) {
  Throwable cause = e.getCause();
  log.error("Log topic producer failed for function: " + e.getMessage(), cause);
  // inspect cause: connectivity, authorization, or topic issues
}

When it happens

Trigger: Broker unavailable or TLS/auth misconfigured when the function instance starts; the function service account lacks produce permission on the log topic; log topic namespace doesn't exist and auto-creation is disabled; invalid producer config (e.g. bad serviceUrl).

Common situations: Function workers pointed at the wrong cluster; logTopic set to an illegal topic name; token/cert expiry at instance startup; network policy blocking broker port from function pods; Pulsar topic auto-creation disabled.

Related errors

• Unable to initialize crypto config %s
• Error creating client for HealthChecker
• maxMessages must be >= 0
• chunkSize must be > 0 when chunking is enabled
• Component cannot get state store

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/b39165a4f8702a60. Report an issue: GitHub.