apache/pulsar · error · NoSuchElementException

NoSuchElementException

Error message

NoSuchElementException

What it means

GrowableArrayBlockingQueue.remove (BlockingQueue contract): the queue was empty at removal time, so there is no element to remove and NoSuchElementException is thrown — the standard j.u.c. behavior for remove() on an empty queue.

Source

Thrown at pulsar-common/src/main/java/org/apache/pulsar/common/util/collections/GrowableArrayBlockingQueue.java:79

    public GrowableArrayBlockingQueue() {
        this(64);
    }

    @SuppressWarnings("unchecked")
    public GrowableArrayBlockingQueue(int initialCapacity) {
        headIndex.value = 0;
        tailIndex.value = 0;

        int capacity = io.netty.util.internal.MathUtil.findNextPositivePowerOfTwo(initialCapacity);
        data = (T[]) new Object[capacity];
    }

    @Override
    public T remove() {
        T item = poll();
        if (item == null) {
            throw new NoSuchElementException();
        }

        return item;
    }

    @Override
    public T poll() {
        return pollIf(v -> true);
    }

    public T pollIf(Predicate<T> predicate) {
        headLock.lock();
        try {
            if (SIZE_UPDATER.get(this) > 0) {
                T item = data[headIndex.value];
                if (!predicate.test(item)) {
                    return null;
                }

View on GitHub (pinned to 820761864e)

Solutions

1. Check size/emptiness before calling remove, or use poll() which returns null

Example fix

// before
T item = queue.remove();
// after
T item = queue.poll();
if (item == null) {
    return; // queue empty
}

if (!queue.isEmpty()) { T item = queue.remove(); ... }
// or preferably: T item = queue.poll();

try {
    T item = queue.remove();
} catch (NoSuchElementException e) {
    // queue was empty
}

When it happens

Trigger: Calling remove() on an empty queue (no elements ever added, or all elements already consumed).

Common situations: Draining a queue in a loop without checking isEmpty, or race where another consumer took the last element between isEmpty and remove.

Related errors

• Unable to determine latest version since broker version map
• ${key} already exists in the dynamicConfigurationMap
• Topic factory failed to create topic
• No more range can assigned to new consumer, assigned consume
• Range conflict with consumer ${conflictingConsumer}

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/a58a2b4a7aa576c1. Report an issue: GitHub.