Bluesky April 2026 Outage Post-Mortem

(pckt.blog)

88 points | by jcalabro 3 hours ago

13 comments

  • threecheese 3 hours ago
    > What I had missed is that we deployed a new internal service last week that sent less than three GetPostRecord requests per second, but it did sometimes send batches of 15-20 thousand URIs at a time. Typically, we'd probably be doing between 1-50 post lookups per request.

    That’ll do it.

    • 98codes 2 hours ago
      Ahh, the three relevant numbers in development: 0, 1, and infinity.
    • jandrese 23 minutes ago
      The incredible part about this is because their backend is all TCP/IP they were literally exhausting the ports by leaving all 65k of them in TIME_WAIT, and the workaround was to start randomizing the localhost address to give them another trillion ports or so.
    • bombcar 2 hours ago
      Zero, one, many, many thousands.
    • LoganDark 18 minutes ago
      And then they fix the issue by using multiple localhost IPs rather than, perhaps, not sending 15-20 thousand URIs at a time
      • odo1242 4 minutes ago
        They mentioned it was a temporary fix that they removed after finding and fixing the true root cause, though.
    • htx80nerd 53 minutes ago
      less than ideal if I had to be frank.
  • drewg123 19 minutes ago
    Golang's use of a potentially unbounded number of threads is just insane. I used to be fairly bullish on golang, but this, combined with the fact that its garbage collected, makes me feel its just unsuitable for production use.
  • tapoxi 43 minutes ago
    I don't really understand this architecture, but I thought Bluesky was distributed like Mastodon? How can it have an outage?
    • pfraze 39 minutes ago
      This writeup is useful for backend engineers: https://atproto.com/articles/atproto-for-distsys-engineers

      The simple answer is that atproto works like the web & search engines, where the apps aggregate from the distributed accounts. So the proper analogy here would be like yahoo going down in 1999.

      • tapoxi 25 minutes ago
        This is a fantastic write-up, thanks for sharing!
      • isodev 34 minutes ago
        Google and MSN Search were already available at this time. Also websites used to publish webrings and there was IRC and forums to ask people about things.
    • isodev 38 minutes ago
      It’s more of a concept of a plan for being distributed. I even went through the trouble of hosting my own PDC and still, I was unable to use the service during the outage
    • Retr0id 39 minutes ago
      Mastodon infra can have outages, too.
      • tapoxi 32 minutes ago
        It's just confined to one instance if it goes down, not all of Mastodon.
    • LoganDark 17 minutes ago
      A web interface and home server can have an outage. Bluesky is just a web interface and home server.
  • mwkaufma 33 minutes ago
    Tell us more about this buggy "new internal service" that's scraping batch data :P
  • goekjclo 1 hour ago
    > The timing of these log spikes lined up with drops in user-facing traffic, which makes sense. Our data plane heavily uses memcached to keep load off our main Scylla database, and if we're exhausting ports, that's a huge problem.

    I expect this is common.

  • pembrook 9 minutes ago
    Distributed social media goes down? hrmmm.

    Email and the internet don't have "downtime." Certain key infra providers do of course. ISPs can go down. DNS providers can go down. But the internet and email itself can't go down absent a global electricity outage.

    You haven't built a decentralized protocol until you reach that standard imo. Otherwise its just "distributed protocol" cosplay. Nice virtue signaling hat, but you aren't the real thing. Kind of like how everybody has been amnesia'd into thinking Obsidian is open source when it really isn't.

    • iAMkenough 7 minutes ago
      Bluesky is a provider. Blacksky didn’t go down.
  • gsibble 38 minutes ago
    Did all 3 users notice?
    • ffsm8 14 minutes ago
      Naw, only one did. Turns out the other two were his socket accounts he used to upvote and comment on his own content.

      Okay, nuff trolling for today

    • dogemaster2027 10 minutes ago
      [dead]
  • electrondood 1 hour ago
    Great write up... curious about the RCA. Thanks!
  • rvz 1 hour ago
    Thank you for the post mortem on this outage.
  • jonstaab 1 hour ago
    nostr never goes down
    • jandrese 31 minutes ago
      If nostr went down would people even notice?
    • pfraze 1 hour ago
      All support to other decentralizers but nothing never goes down.
      • jonstaab 55 minutes ago
        1000x redundancy makes it vanishingly unlikely. Although I know we're due for a pole shift so all bets are off I suppose.
  • dogemaster2027 24 minutes ago
    [dead]
  • templar_snow 2 hours ago
    [flagged]
  • jmclnx 1 hour ago
    Lite Blue on a dark Blue background. That is a new one, I have seen grey text on lite grey, but blue on blue ?

    The article does work in lynx, at least I can read it.