public ByteBuf get() {
        ByteBuf buffer = pool.poll();
        if (buffer == null) {
            return allocate();
        }
        poolSize.decrementAndGet();
        return buffer;
    }
Get a {@link ByteBuf} from the pool.
If the pool is empty, a new {@link ByteBuf} will be allocated.
s3stream/src/main/java/com/automq/stream/FixedSizeByteBufPool.java