{"record":{"id":"8350e6a66fc6309b","repo":"MyCATApache/Mycat-Server","slug":"the-ring-buffer-cannot-accommodate-batchsize-it","errorCode":null,"errorMessage":"The ring buffer cannot accommodate ${batchSize} it only has space for ${bufferSize} entities.","messagePattern":"The ring buffer cannot accommodate (.+?) it only has space for (.+?) entities\\.","errorType":"validation","errorClass":"IllegalArgumentException","httpStatus":null,"severity":"error","filePath":"src/main/java/io/mycat/memory/unsafe/ringbuffer/RingBuffer.java","lineNumber":281,"sourceCode":"    private void checkBounds(final EventTranslator<E>[] translators, final int batchStartsAt, final int batchSize) {\n        checkBatchSizing(batchStartsAt, batchSize);\n        batchOverRuns(translators, batchStartsAt, batchSize);\n    }\n\n    private <A> void batchOverRuns(final A[] arg0, final int batchStartsAt, final int batchSize) {\n        if (batchStartsAt + batchSize > arg0.length) {\n            throw new IllegalArgumentException(\n                    \"A batchSize of: \" + batchSize +\n                            \" with batchStatsAt of: \" + batchStartsAt +\n                            \" will overrun the available number of arguments: \" + (arg0.length - batchStartsAt));\n        }\n    }\n\n    private void checkBatchSizing(int batchStartsAt, int batchSize) {\n        if (batchStartsAt < 0 || batchSize < 0) {\n            throw new IllegalArgumentException(\"Both batchStartsAt and batchSize must be positive but got: batchStartsAt \" + batchStartsAt + \" and batchSize \" + batchSize);\n        } else if (batchSize > bufferSize) {\n            throw new IllegalArgumentException(\"The ring buffer cannot accommodate \" + batchSize + \" it only has space for \" + bufferSize + \" entities.\");\n        }\n    }\n\n    /**\n     * @see io.mycat.memory.unsafe.ringbuffer.common.event.EventSink#publishEvent(EventTranslator)\n     */\n    @Override\n    public void publishEvents(EventTranslator<E>[] translators) {\n        publishEvents(translators, 0, translators.length);\n    }\n\n    private void translateAndPublishBatch(\n            final EventTranslator<E>[] translators, int batchStartsAt,\n            final int batchSize, final long finalSequence) {\n        final long initialSequence = finalSequence - (batchSize - 1);\n        try {\n            long sequence = initialSequence;\n            final int batchEndsAt = batchStartsAt + batchSize;","sourceCodeStart":263,"sourceCodeEnd":299,"githubUrl":"https://github.com/MyCATApache/Mycat-Server/blob/65f8d8beb752f935752f2a0eec0ab017facab9ef/src/main/java/io/mycat/memory/unsafe/ringbuffer/RingBuffer.java#L263-L299","documentation":"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.","triggerScenarios":"Calling batch publish APIs with batchSize > bufferSize, e.g. publishing 5000 events at once into a RingBuffer constructed with bufferSize = 1024.","commonSituations":"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.","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."],"exampleFix":"// before\nring.publishEvents(translators, 0, 5000); // capacity 1024\n// after\nfor (int i = 0; i < translators.length; i += 1024) {\n    int n = Math.min(1024, translators.length - i);\n    ring.publishEvents(translators, i, n);\n}","handlingStrategy":"validation","validationCode":"int chunkSize = Math.min(batchSize, ringBufferSize); // ringBufferSize must be the constructed power-of-2 capacity\nfor (int i = 0; i < translators.length; i += chunkSize) {\n    int n = Math.min(chunkSize, translators.length - i);\n    ring.publishEvents(translators, i, n);\n}","typeGuard":null,"tryCatchPattern":"try {\n    ring.publishEvents(translators, 0, requestedBatch);\n} catch (IllegalArgumentException e) {\n    // split into capacity-sized chunks and republish\n    publishInChunks(ring, translators);\n}","preventionTips":["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"],"tags":["java","ringbuffer","capacity","batch"],"backgroundTag":"value-out-of-range","analyzedSha":"65f8d8beb752f935752f2a0eec0ab017facab9ef","analyzedAt":"2026-09-11T00:12:21.696Z","contentChangedAt":"2026-09-11T00:12:21.696Z","schemaVersion":2},"datasetVersion":"2026-09-16T04:17:20.429Z"}