t8y2/dbx · warning · IllegalArgumentException

Peek message count must be between 1 and " + MAX_PEEK_MESSAG

Error message

Peek message count must be between 1 and " + MAX_PEEK_MESSAGE_COUNT

What it means

KafkaAgent.validatePeekCount enforces that the `count` parameter of a peek operation is between 1 and MAX_PEEK_MESSAGE_COUNT. The library throws this IllegalArgumentException before creating a consumer to fail fast on out-of-range peek sizes. It protects the driver from building enormous fetch requests or returning unbounded result sets.

Source

Thrown at agents/drivers/kafka/src/main/java/com/dbx/agent/kafka/KafkaAgent.java:1708

                );
            }
            List<Map<String, Object>> messages = sortAndLimitPeekedMessages(
                collection.messages, count, startPosition
            );
            return peekMessagesResult(messages, collection.incomplete);
        }
    }

    static Map<String, Object> peekMessagesResult(List<Map<String, Object>> messages, boolean incomplete) {
        Map<String, Object> result = new LinkedHashMap<>();
        result.put("messages", messages);
        result.put("incomplete", incomplete);
        return result;
    }

    static int validatedPeekCount(int count) {
        if (count < 1 || count > MAX_PEEK_MESSAGE_COUNT) {
            throw new IllegalArgumentException(
                "Peek message count must be between 1 and " + MAX_PEEK_MESSAGE_COUNT
            );
        }
        return count;
    }

    static int peekRequestTimeoutMs(JsonObject conn, Properties props) {
        Integer connectionTimeout = integerOrNull(conn, "request_timeout_ms");
        if (connectionTimeout != null) {
            return positiveTimeoutMs("request_timeout_ms", connectionTimeout);
        }
        String configuredTimeout = props.getProperty(
            ConsumerConfig.REQUEST_TIMEOUT_MS_CONFIG,
            String.valueOf(DEFAULT_REQUEST_TIMEOUT_MS)
        );
        try {
            return positiveTimeoutMs(ConsumerConfig.REQUEST_TIMEOUT_MS_CONFIG, Integer.parseInt(configuredTimeout));
        } catch (NumberFormatException error) {

View on GitHub (pinned to c0390bff16)

Solutions

1. Clamp the requested count into the range [1, MAX_PEEK_MESSAGE_COUNT] before calling the peek API.
2. Default to a small sane value (e.g. 10) when the caller supplies 0/null.
3. Catch IllegalArgumentException and surface a validation message to the user prompting a value in range.

Example fix

// before
agent.peek(conn, topic, count /* count = 0 */);

// after
int safeCount = Math.max(1, Math.min(count, MAX_PEEK_MESSAGE_COUNT));
agent.peek(conn, topic, safeCount);

int MAX_PEEK_MESSAGE_COUNT = 100; // match driver constant
if (count < 1 || count > MAX_PEEK_MESSAGE_COUNT) {
    throw new IllegalArgumentException("count must be in [1, " + MAX_PEEK_MESSAGE_COUNT + "]");
}

boolean isValidPeekCount(int count) { return count >= 1 && count <= 100; }

try {
    result = agent.peek(conn, topic, count);
} catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("Peek message count")) {
        result = agent.peek(conn, topic, 10); // safe default
    } else throw e;
}

When it happens

Trigger: Calling the Kafka peek API with count < 1 (e.g. 0 or negative) or count > MAX_PEEK_MESSAGE_COUNT. validatedPeekCount is invoked on every peek request that specifies a message count.

Common situations: Defaulting a UI page size to 0 before the user picks a value; passing a raw user input string parsed to 0; copying a 'limit' of 0 from another connector; requesting tens of thousands of messages to 'drain' a topic.

Related errors

• offsets must be an array
• ${name} must be a positive integer
• Kafka partition ${partition} does not exist for topic '${top
• Unsupported peek startPosition: ${value}
• partition must be non-negative

AI-assisted analysis of t8y2/dbx@c0390bff16 (2026-09-05). Data as JSON: /api/errors/dc273891b8149613. Report an issue: GitHub.