Bluesky April 2026 Outage Post-Mortem (pckt.blog)
87 points by jcalabro 3 hours ago
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 3 hours ago
Ahh, the three relevant numbers in development: 0, 1, and infinity.
jandrese 20 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 3 hours ago
Zero, one, many, many thousands.
LoganDark 14 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 a few seconds ago
They mentioned it was a temporary fix that they removed after finding and fixing the true root cause, though.
htx80nerd an hour ago
less than ideal if I had to be frank.
drewg123 15 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 39 minutes ago
I don't really understand this architecture, but I thought Bluesky was distributed like Mastodon? How can it have an outage?
pfraze 35 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 22 minutes ago
This is a fantastic write-up, thanks for sharing!
isodev 30 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 34 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 36 minutes ago
Mastodon infra can have outages, too.
tapoxi 28 minutes ago
It's just confined to one instance if it goes down, not all of Mastodon.
LoganDark 13 minutes ago
A web interface and home server can have an outage. Bluesky is just a web interface and home server.
mwkaufma 30 minutes ago
Tell us more about this buggy "new internal service" that's scraping batch data :P
pembrook 5 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 3 minutes ago
Bluesky is a provider. Blacksky didn’t go down.
goekjclo 2 hours 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.
gsibble 35 minutes ago
Did all 3 users notice?
ffsm8 10 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
electrondood an hour ago
Great write up... curious about the RCA. Thanks!
rvz 2 hours ago
Thank you for the post mortem on this outage.
jonstaab an hour ago
nostr never goes down
jandrese 27 minutes ago
If nostr went down would people even notice?
jonstaab 24 minutes ago
probably not
pfraze an hour ago
All support to other decentralizers but nothing never goes down.
jonstaab an hour ago
1000x redundancy makes it vanishingly unlikely. Although I know we're due for a pole shift so all bets are off I suppose.
jmclnx 2 hours 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.