v0.6.1 - Empty DHT routing table

[hsanjuan]

Since v0.6.1 I have a few of my tests are failing because the DHT routing table is empty, therefore discovery does not work any more.

The host setup process is as follows:

• N Hosts are created
• 1 Additional host is created
• This additional host does host.Connect(...) to each of the N hosts

The DHTs for each host are created before opening a connection.

Each of the N hosts is expected to be able to find routing to any of the others, with discovery happening via the DHT.

The routing table should have received 1 entry upon Connect and therefore auto-discovered everyone else on the first routing table refresh. However, this refresh is having no effect. Logs show how the refresh fails:

2020-04-07T00:59:25.105+0200    WARN    dht     go-libp2p-kad-dht@v0.6.1/dht_bootstrap.go:125   failed when refreshing routing table   {"error": "1 error occurred:\n\t* failed to do a random walk for cpl 0: failed to find any peer in table\n\n"}

This worked in v0.5.2. Any ideas on why there are no peers in the routing table when one peer has opened a connection?

[aschmahmann]

@hsanjuan it's hard to say exactly what the problem is without looking at the test, can you post the link?

A diagnostic questions though: are you waiting for the DHTs to be connected to each other (e.g. periodically polling routing table sizes to see if > 1) or doing something racy like time.Sleep(time.Second)? If you're doing this in a racy way I'd recommend doing some polling like we do with

go-libp2p-kad-dht/dht_test.go

Line 700 in 067f8ab

func waitForWellFormedTables(t *testing.T, dhts []*IpfsDHT, minPeers, avgPeers int, timeout time.Duration) bool {

This will inform us whether there's an issue wherein the routing table will never populate.

[Stebalien]

Ah, wait... The DHT now defaults to starting in "auto" mode. A DHT node will only transition to server mode if it finds an AutoNAT server that tells it that it's dialable. That's probably your issue.

I've filed two related issues: #564, libp2p/go-libp2p-autonat#73.

(and I'm going to cut an RC without the mode switching for now)

[hsanjuan]

Thanks, I'm closing this in favor of the other issues.