Shorter chain is chosen in re-org when totalDifficulty is the same

[guoyiteng]

Hi, I noticed that geth picked up the the shorter chain when totalDifficulty is the same in ForkChoice. May I ask why this is the case?
https://github.com/ethereum/go-ethereum/blob/master/core/forkchoice.go#L96

number, headNumber := header.Number.Uint64(), current.Number.Uint64()

Also the variable name headerNumber here is a bit confusing. I know this came from a recent refactor #23761 but it would be clearer if we can rename these two variables to something like headerNumber, number.

[rjl493456442]

Regarding the reason for choosing the block with lower number, maybe you can try to read the paper we linked here.

And about the variable names, I think number, headNumber is better. current here refers to the local head header, and the header refers to a header given by a remote peer(so no guarantee it can be the canonical chain head).