Ext data too large; 2**32-1

[kawochen]

In this line , should the max length be (size_t) -1 instead?

[methane]

See https://github.com/msgpack/msgpack/blob/master/spec.md#formats-ext

Msgpack is suitable for small~medium data fits in memory.
When treating large data, "sequence of small message" is better than "one message has large array".

[kawochen]

Thanks!