private final IntIndexMap<OutboundMessage> outboundMessages = new IntIndexHashMap<OutboundMessage>(OutboundMessage.INDEXER, Equaller.IDENTITY, 512, 0.5f);
    private final IntIndexMap<InboundMessage> inboundMessages = new IntIndexHashMap<InboundMessage>(InboundMessage.INDEXER, Equaller.IDENTITY, 512, 0.5f);

    public MessageOutputStream writeMessage() throws IOException {
        int tries = 50;
        IntIndexMap<OutboundMessage> outboundMessages = this.outboundMessages;
        openOutboundMessage();
        boolean ok = false;
        try {
            final Random random = ThreadLocalRandom.current();
            while (tries > 0) {
                final int id = random.nextInt() & 0xfffe;
                if (! outboundMessages.containsKey(id)) {
                    OutboundMessage message = new OutboundMessage((short) id, this, outboundWindow, maxOutboundMessageSize, messageAckTimeout);
                    OutboundMessage existing = outboundMessages.putIfAbsent(message);
                    if (existing == null) {
                        ok = true;
                        return message;
                    }
                }
                tries --;
            }
            throw log.channelBusy();
        } finally {
            if (! ok) {
                closeOutboundMessage();
            }
        }
    }