大家好，我是君哥。
Kafka 是一款性能非常优秀的消息队列，每秒处理的消息体量可以达到千万级别。今天来聊一聊 Kafka 高性能背后的技术原理。
1、批量发送
Kafka 收发消息都是批量进行处理的。我们看一下 Kafka 生产者发送消息的代码：
private Future<RecordMetadata> doSend(ProducerRecord<K, V> record, Callback callback) {
TopicPartition tp = null;
try {
//省略前面代码
Callback interceptCallback = new InterceptorCallback<>(callback, this.interceptors, tp);
//把消息追加到之前缓存的这一批消息上
RecordAccumulator.RecordAppendResult result = accumulator.append(tp, timestamp, serializedKey,
serializedValue, headers, interceptCallback, remainingWaitMs);
//积累到设置的缓存大小，则发送出去
if (result.batchIsFull || result.newBatchCreated) {
log.trace("Waking up the sender since topic {} partition {} is either full or getting a new batch", record.topic(), partition);
this.sender.wakeup();
}
return result.future;
// handling exceptions and record the errors;
// for API exceptions return them in the future,
// for other exceptions throw directly
} catch /**省略 catch 代码*/
}