Race condition in SimpleNetworkWrapper; error locations

gistfile1.txt

Breakpoint on IndexOutOfBoundsException
AbstractByteBuf::
    @Override
    public ByteBuf readerIndex(int readerIndex) {
        if (readerIndex < 0 || readerIndex > writerIndex) {
            throw new IndexOutOfBoundsException(String.format(
                    "readerIndex: %d (expected: 0 <= readerIndex <= writerIndex(%d))", readerIndex, writerIndex));
        }
        this.readerIndex = readerIndex;
        return this;
    }
    
Further up the call stack is

AbstractByteBuf::
    @Override
    public ByteBuf writeBytes(ByteBuf src, int length) {
        if (length > src.readableBytes()) {
            throw new IndexOutOfBoundsException(String.format(
                    "length(%d) exceeds src.readableBytes(%d) where src is: %s", length, src.readableBytes(), src));
        }
        // at this point we have just checked that there is at least 7 bytes remaining to be read.
        writeBytes(src, src.readerIndex(), length);
        src.readerIndex(src.readerIndex() + length);  ///<--- here; length = 7, but causes a failure, i.e. something has advanced src by 1.
        return this;
    }


S3FPacketCustomPayload::
    public void writePacketData(PacketBuffer buf) throws IOException
    {
        buf.writeString(this.channel);
        synchronized(this) { //This may be access multiple times, from multiple threads, lets be safe.
        this.data.markReaderIndex();         // markedReaderIndex == 0
        buf.writeBytes((ByteBuf)this.data);  // <------------- here
        this.data.resetReaderIndex();
        }
    }