presto-main/src/main/java/io/prestosql/operator/exchange/RandomExchanger.java/RandomExchanger/accept
class RandomExchanger:    @Override
    public void accept(Page page)
    {
        memoryManager.updateMemoryUsage(page.getRetainedSizeInBytes());

        PageReference pageReference = new PageReference(page, 1, () -> memoryManager.updateMemoryUsage(-page.getRetainedSizeInBytes()));

        int randomIndex = ThreadLocalRandom.current().nextInt(buffers.size());
        buffers.get(randomIndex).accept(pageReference);
    }