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Comment by djtriptych | Hacker News Reader

Could it be the obvious? Everyone signing on / loading slack clients at the same time?

My gut feeling is everyone coming out of the holidays reading back weeks of notifications.

then wouldn't this happen every monday morning?

Perhaps it is a large number of people checking into channels that are backlogged with lots of bot message notifications.

A lot of organizations essentially took the last two weeks off from work, which is long enough for a 10-day autoscale window to spin down servers, and then get confronted by a load spike that wasn't pre-spun for.

I would be shocked if Slack operations wasn’t aware of this return to work spike and didn’t pre-scale in anticipation.

I wouldn't, since my personal theory is that the outage is due to AWS and GCP autoscale capacity exhaustion. We'll find out soon enough!

EDIT: And down goes Notion, too: https://news.ycombinator.com/item?id=25634159

>AWS and GCP autoscale capacity

What does this mean? What do cloud providers do when customers scale down their services? Do the providers literally power down servers? Do they sell the capacity to new customers?

They rate limit how fast you can auto scale which is dependent on a slew of factors.

They sell unused capacity at a much lower price (spot instances on AWS, preemptible VMs on GCP).

I don't know if they power down some servers if usage stays low for a very long time.

That doesn’t mean they chose the right number to scale to.

See for example, Amazon Prime day:

https://www.cnbc.com/2018/07/19/amazon-internal-documents-wh...

This is after many had a week vacation. I'm sure most weekends some people pop in and out, and logins are more staggered on a typical monday morning.

Just a theory though.

Nice of you to ignore the majority of the world's population who have been up and working long before America woke up.

Relax. GP is clearly referring to an increase in people signing on do to the holidays ending and everyone coming back from work.

Also, Slack has significantly more users in the US than in any other country[1], and it really isn't even close. So the offense you're taking is unwarranted anyway.

1: https://saasscout.com/statistics/slack-stats/

Slack makes ~61% of its revenue from US customers which only has 4 time zones compared to the remainder of their revenue being spread out across ~20 time zones. It's not an unreasonable hypothesis.

See page 12 of the document (which is page 14 of the PDF) https://d18rn0p25nwr6d.cloudfront.net/CIK-0001764925/70df834...

Slack most likely has more US customers but

- Revenue is not same as users. Slack have tons of free users and some countries also has lower priced plans.

- Many companies like Amazon etc. probably is counted as US revenue for Slack but they have more than 30% of their employees outside the US. This should not be huge numbers but significant.

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