4 ms·

> via round robin DNS (meaning that when people resolve the DNS it gives them a random server from the set of 20 to connect to) Most of the times, it's not sim

> via round robin DNS (meaning that when people resolve the DNS it gives them a random server from the set of 20 to connect to) Most of the times, it's not simple round-robin, but also geo-based. This means clients will get ip addresses of the servers closest to them.

magila 5y ago
My experience with Freenode/Libra Chat is that they either don't implement geo DNS or don't do a very good job of it. I'm on the US west coast and lookups to irc.libera.chat often return servers in Europe. Edit: Double checking Libra Chat's website I see that they have added regional hostnames so I guess that's their solution.
- pvtmert 5y ago
  if they're using aws route53, your isp needs to support edns. otherwise, your netblock might have been falsely advertised in the dns provider's geoip database. (eg. maxmind)
  - pushrax 5y ago
    They're using Cloudflare. When I resolve them from the east coast, I got a San Francisco server once and a server in Budapest once. They have a server in Toronto, Ashburn, Montreal, and other places that are closer. I know geodns works here since I use it for some of my own deployments.
melony 5y ago
Does IRC predates distributed state machines? Why can't the servers sync up the chat via Paxos or Raft?
- sterlind 5y ago
  hard to do Paxos over large geographical distances efficiently, but... it's IRC, so.. I just assume it was from an earlier internet where distributed systems weren't as well understood. I don't think it necessarily predates Paxos but it definitely predates Paxos being a household name.
- X6S1x6Okd1st 5y ago
  paxos was first created 1989, but not popularized for a long while after: https://en.m.wikipedia.org/wiki/Paxos_(computer_science) https://en.m.wikipedia.org/wiki/Paxos_(computer_science) irc 1988: https://en.m.wikipedia.org/wiki/Internet_Relay_Chat https://en.m.wikipedia.org/wiki/Internet_Relay_Chat Earliest reference for raft I can find is 2013.
- manquer 5y ago
  Chat is not that complex as other distributed applications you probably don't need Raft.Both Paxos and Raft are very complex algorithms to implement. A CRDT based append only implementation is probably more than enough?. Data is never modified only added/removed in typical chat workflows. Reading discourd engineering blog over the years it looks like scaling the pub/sub for the consumers in large channels is lot harder than DB/store itself being distributed.
- giantrobot 5y ago
  Distributing state wasn't the goal on IRC, only relaying messages. If you miss a message you miss a message. You can use client-side tools (bots, bouncers, etc) to record state but the protocol itself doesn't care.
  - jandrese 5y ago
    IRC is sized to run on 80s hardware. Storing messages wasn’t possible because few nodes would have enough memory to store more than a handful of messages. The links were so slow that spitting over a backlog on reconnect could stall the connection for a non-trivial amount of time.
- duskwuff 5y ago
  Implementing Paxos would mean that stateful operations (like connecting to the server, joining a channel, or changing modes) become impossible on a server, or a group of servers, that have lost quorum.

magila 5y ago

My experience with Freenode/Libra Chat is that they either don't implement geo DNS or don't do a very good job of it. I'm on the US west coast and lookups to irc.libera.chat often return servers in Europe. Edit: Double checking Libra Chat's website I see that they have added regional hostnames so I guess that's their solution.

pvtmert 5y ago
if they're using aws route53, your isp needs to support edns. otherwise, your netblock might have been falsely advertised in the dns provider's geoip database. (eg. maxmind)
- pushrax 5y ago
  They're using Cloudflare. When I resolve them from the east coast, I got a San Francisco server once and a server in Budapest once. They have a server in Toronto, Ashburn, Montreal, and other places that are closer. I know geodns works here since I use it for some of my own deployments.

melony 5y ago

Does IRC predates distributed state machines? Why can't the servers sync up the chat via Paxos or Raft?

sterlind 5y ago
hard to do Paxos over large geographical distances efficiently, but... it's IRC, so.. I just assume it was from an earlier internet where distributed systems weren't as well understood. I don't think it necessarily predates Paxos but it definitely predates Paxos being a household name.
X6S1x6Okd1st 5y ago
paxos was first created 1989, but not popularized for a long while after: https://en.m.wikipedia.org/wiki/Paxos_(computer_science) https://en.m.wikipedia.org/wiki/Paxos_(computer_science) irc 1988: https://en.m.wikipedia.org/wiki/Internet_Relay_Chat https://en.m.wikipedia.org/wiki/Internet_Relay_Chat Earliest reference for raft I can find is 2013.
manquer 5y ago
Chat is not that complex as other distributed applications you probably don't need Raft.Both Paxos and Raft are very complex algorithms to implement. A CRDT based append only implementation is probably more than enough?. Data is never modified only added/removed in typical chat workflows. Reading discourd engineering blog over the years it looks like scaling the pub/sub for the consumers in large channels is lot harder than DB/store itself being distributed.
giantrobot 5y ago
Distributing state wasn't the goal on IRC, only relaying messages. If you miss a message you miss a message. You can use client-side tools (bots, bouncers, etc) to record state but the protocol itself doesn't care.
- jandrese 5y ago
  IRC is sized to run on 80s hardware. Storing messages wasn’t possible because few nodes would have enough memory to store more than a handful of messages. The links were so slow that spitting over a backlog on reconnect could stall the connection for a non-trivial amount of time.
duskwuff 5y ago
Implementing Paxos would mean that stateful operations (like connecting to the server, joining a channel, or changing modes) become impossible on a server, or a group of servers, that have lost quorum.