By default, the number of gRPC channel is set to 1 channel and the max rpc per channel is set to Integer.MAX_VALUE. However, the max rpc per channel is set to 100 on GFE(pending confirmation), if a channel is overloaded and maxRpcsPerChannel is not set, ChannelPool will not resize correctly and would cause performance degradation. There is a related issue in gRPC repo.

We need to set the default maxRpcsPerChannel to 100, and prevents it from being set to any number that is greater than 100.

We also need to make sure directpath is not affected by this, as directpath doesn't suffer all the same limits as GFEs.