karalabe / minority Public

As of writing, Ethereum has multiple client implementations, but Geth / go-ethereum stands out as a majority client with around 80-90% network ownership. Although this is an ode the client's stability and to its developers, it is also a situation with undesirable consequences.

The former issue is somewhat bad as it causes an outage, but that's about the worst that can happen. The latter issue, however, is especially bad, as it can cause double spends by irreversibly reacting to a false (invalid) state of the network. High profile users (e.g. exchanges) work around the above issues by running multiple flavor clients side by side and raise an alarm (e.g. disable deposits / withdrawals) when they disagree.

Mining pools usually also run multiple client flavors, though for them, it's worthwhile to mine on both sides of a chain split until the devs figure out what's happening, since that hedges them against losing all their earnings in case of being on the wrong side of history. Either way, the chain can still progress, the invalid side-chain being eventually orphaned. Life goes on.

The former case is again the lesser problem, users waiting for chain finality will never receive it, so their operations might go "offline" until the issue is fixed. The latter case however is a big problem, as an invalid state is marked final and may be acted upon. It can be fixed with a rollback to the last good state (same as on the PoW chain), but it invalidates the notion of finality.

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