mprime1

There are some restrictions.

I had the foolish idea of installing a Tesla charger at home to charge my Bolt. I’ve been unable to ever use it.

The wall charger works fine with Teslas. My car and adapter charge fine at Tesla superchargers.

But the home Tesla charger refuses to charge my Bolt. (Yes I disabled vehicle restrictions and tried all sorts of combinations of settings for weeks before giving up. Tesla support was useless of course)

Restriction or bug, same difference.

> never really understood how just adding extra invisible stuff to make the equations work is justified

IANAP but here’s my understanding.

At the end of the month you spent $2000, you’re not sure how so you track down your expenses:

  - rent $500
  - groceries $120
  - gas $80
  - …
  - unknown: $123

That ‘unknown’ is dark matter. It’s a placeholder. It’s there and makes your total but you can’t explain it yet.

My anecdotal evidence confirms this. Friends in my home country are hooked on Telegram meme groups and as a result they’re spreading [Russian propaganda] conspiracy theories at alarming levels.

(Russia is really good at weaponizing memes but I don’t meant to single it out, the US has also been very successfully influencing the same country for decades via Hollywood movies for example)

Stay humble

  - There is someone else that is better at X than you are
  - The person not so good at X is probably better than you at Y

Same thing as what?

Parent was asking about deduping encrypted data.

Someone said (wrongly) it’s impossible and I shared a popular project that does exactly that.

I had a fascinating conversation with someone that has been working on this system for the last 20 or so years.

Water treatment is powered by the geyser and in turn the leftover brown water feeds the geyser.

Pretty neat (for sewage)!

Ordering gives you ... ordering. And nothing more.

Process 1 receives: 3:00 [1] "P1 is leader" 3:01 [2] "P2 is leader"

Process 2 receives: 3:00 [1] "P1 is leader" 4:00 [2] "P2 is leader"

This is perfectly valid Atomic Broadcast. Order is maintained.

However from 3:01 to 4:00PM you have 2 leaders (or 2 processes holding the lock).

Don't use ABCast to do locking / leader election for your "user-space" application!

Rounding up 'usually works' to 'is reliable' is a recipe for building crappy systems.

Rounding down 'usually works' to 'it's not perfect and we need to handle edge cases' is how you build dependable systems.

Your first comment seemed very much in the first camp to me.

The fatal flaw is calling them "locks".

When programmers think of locks, they think of something that can be used to guarantee mutual exclusion.

Distributed locks have edge cases where mutual exclusion is violated.

Implementation does not matter.

e.g. imagine someone shows you a design for a perpetual motion machine. You don't need to know the details to know it doesn't work! It would violate the laws of physics!

Similarly, anyone telling you they created an implementation of a distributed lock that is safe, is claiming their system breaks the laws of information theory.

"Distributed locks" are at best contention-reduction mechanisms. i.e. they can keep multiple processes from piling up and slowing each other down.

[Some] Paxos for example use leader election to streamline the protocol and achieve high throughput. But Paxos safety does NOT depend on it. If there are multiple leaders active (which will inevitably happen), the protocol still guarantees its safety properties.