[providers] Fallback provider hangs

Describe the bug When using a FallbackProvider if you have an RPC that hangs, the entire request will hang even if other RPCs are returning quickly without issue.

Important usage note: this issue was reproduced with a quorum of 1 (either because there are only 2 provider URLs used, or quorum is explicitly set to 1.

Reproduction steps

import { JsonRpcProvider, FallbackProvider } from "@ethersproject/providers";

// Must use a list of URLs where one does not return quickly.
// This is the exhibited error behavior for some invalid or overloaded RPCs :(
const urls = ["http://....", "http://...."];
const providers = urls.map(url => new JsonRpcProvider(url));
const fallback = new FallbackProvider(providers, 1);
const promise = fallback.getBlockNumber();
await promise; // Hangs!

Environment: Reproducible in a node repl, difficult part is finding a URL that hangs! Using "ethers": "^5.4.6"

[gitpusha]

We noticed the same issue

[humblecoder]

Any updates on this? I’m having the same issue. Also, more detailed information overall (and perhaps even a quality recovery mechanism) would be nice.

I receive the call that timed out (e.g. method:eth_blockNumber), but no indication as to why the timeout occurred. I realize you can really only provide whatever info the node sends back, but perhaps some info on why every fallback provider failed would be useful.

Timing out (when you have 3 endpoints configured) then receiving noNetwork afterward (perpetually) while still being able to manually geth attach to every single endpoint listed (or run separate simultaneous scripts that use the same nodes) is 🤯 to say the least.