You can publish multiple messages at the same time by using message batches. To use a message batch, you must create a Junges\Kafka\Producers\MessageBatch instance. Then create as many messages as you want and push them to the MesageBatch instance. Finally, create your producer and call the sendBatch, passing the MessageBatch instance as a parameter. This is helpful when you persist messages in storage before publishing (e.g. TransactionalOutbox Pattern).

use Junges\Kafka\Facades\Kafka;
use Junges\Kafka\Producers\MessageBatch;
use Junges\Kafka\Message\Message;

$message = new Message(
    headers: ['header-key' => 'header-value'],
    body: ['key' => 'value'],
    key: 'kafka key here'  
)

$messageBatch = new MessageBatch();
$messageBatch->push($message);
$messageBatch->push($message);
$messageBatch->push($message);
$messageBatch->push($message);

/** @var \Junges\Kafka\Producers\ProducerBuilder $producer */
$producer = Kafka::publishOn('topic')
    ->withConfigOptions(['key' => 'value']);

$producer->sendBatch($messageBatch);