What's the biggest number of machines do we support in one group?

[jovany-wang]

We're now using CPU + tcp + redis store in our cluster with 250 machines.
It works well when the gloo instances number is under 1k in one group, but it fails with connect refused, connect timeout when connectFullMesh() when the gloo instances number > 1k(we're using 1.5k).

So I'd like to know the biggest number of gloo instances we support in one group.

[jovany-wang]

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