MyCATApache/Mycat-Server · error · IllegalArgumentException

The ring buffer cannot accommodate

Error message

The ring buffer cannot accommodate ${batchSize} it only has space for ${bufferSize} entities.

What it means

checkBatchSizing enforces that a batch does not exceed the ring buffer's total capacity (bufferSize). A batchSize larger than the buffer can never fit in one batch, so IllegalArgumentException is thrown stating the requested count and the buffer capacity.

Solutions

Chunk the events into batches of at most bufferSize (or less) and publish each chunk.
Increase the ring buffer's power-of-2 capacity to cover the largest expected batch.
Use the blocking publishEvents variant after splitting, or tryPublishEvents with backpressure handling for overflow.
Log/validate batch sizes against capacity at startup.

Example fix

// before
ring.publishEvents(translators, 0, 5000); // capacity 1024
// after
for (int i = 0; i < translators.length; i += 1024) {
    int n = Math.min(1024, translators.length - i);
    ring.publishEvents(translators, i, n);
}

Defensive patterns

Strategy: validation

Validate before calling

int chunkSize = Math.min(batchSize, ringBufferSize); // ringBufferSize must be the constructed power-of-2 capacity
for (int i = 0; i < translators.length; i += chunkSize) {
    int n = Math.min(chunkSize, translators.length - i);
    ring.publishEvents(translators, i, n);
}

Try / catch

try {
    ring.publishEvents(translators, 0, requestedBatch);
} catch (IllegalArgumentException e) {
    // split into capacity-sized chunks and republish
    publishInChunks(ring, translators);
}

Prevention

Keep batch size <= ring buffer capacity as an invariant in batch-publish helpers
If buffer capacity config changes, update batch size constants together
Chunk large imports/bulk loads instead of one giant publish

When it happens

Trigger: Calling batch publish APIs with batchSize > bufferSize, e.g. publishing 5000 events at once into a RingBuffer constructed with bufferSize = 1024.

Common situations: Bulk-loading historical data into a small ring buffer, a config change that shrank the buffer size while batch code still uses the old larger constant, or unbounded caller-supplied lists passed straight through as batchSize.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/8350e6a66fc6309b. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/memory/unsafe/ringbuffer/RingBuffer.java:281

    private void checkBounds(final EventTranslator<E>[] translators, final int batchStartsAt, final int batchSize) {
        checkBatchSizing(batchStartsAt, batchSize);
        batchOverRuns(translators, batchStartsAt, batchSize);
    }

    private <A> void batchOverRuns(final A[] arg0, final int batchStartsAt, final int batchSize) {
        if (batchStartsAt + batchSize > arg0.length) {
            throw new IllegalArgumentException(
                    "A batchSize of: " + batchSize +
                            " with batchStatsAt of: " + batchStartsAt +
                            " will overrun the available number of arguments: " + (arg0.length - batchStartsAt));
        }
    }

    private void checkBatchSizing(int batchStartsAt, int batchSize) {
        if (batchStartsAt < 0 || batchSize < 0) {
            throw new IllegalArgumentException("Both batchStartsAt and batchSize must be positive but got: batchStartsAt " + batchStartsAt + " and batchSize " + batchSize);
        } else if (batchSize > bufferSize) {
            throw new IllegalArgumentException("The ring buffer cannot accommodate " + batchSize + " it only has space for " + bufferSize + " entities.");
        }
    }

    /**
     * @see io.mycat.memory.unsafe.ringbuffer.common.event.EventSink#publishEvent(EventTranslator)
     */
    @Override
    public void publishEvents(EventTranslator<E>[] translators) {
        publishEvents(translators, 0, translators.length);
    }

    private void translateAndPublishBatch(
            final EventTranslator<E>[] translators, int batchStartsAt,
            final int batchSize, final long finalSequence) {
        final long initialSequence = finalSequence - (batchSize - 1);
        try {
            long sequence = initialSequence;
            final int batchEndsAt = batchStartsAt + batchSize;

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