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0 pointstombert10mo ago0 comments

Yeah, similarly, Joe Armstrong (RIP), co-creator of Erlang explained it to me like this:

> In distributed systems there is no real shared state (imagine one machine in the USA another in Sweden) where is the shared state? In the middle of the Atlantic? — shared state breaks laws of physics. State changes are propagated at the speed of light — we always know how things were at a remote site not how they are now. What we know is what they last told us. If you make a software abstraction that ignores this fact you’ll be in trouble.

He wrote this to me in 2014, and it has really informed how I think about these things.

0 comments

throwawaymaths10mo ago

The thing is that go channels themselves are shared state (if the owner closes the channel and a client tries to write you're not gonna have a good time)! Erlang message boxes are not.

tombertOP10mo ago

Strictly speaking they’re shared state, but the way you model your application around channels is generally to have independent little chunks of work and the channels are just a means of communicating. I know it’s not one-for-one with Erlang.

Kubuxu10mo ago

You can think of closing the channel as sending a message “there will be no further messages”, the panic on write is enforcement of that contract.

Additionally the safe way to use closing of a channel is the writer closing it. If you have multiple writers, you have to either synchronise them, or don’t close the channel.

throwawaymaths10mo ago

Sure but the fact that it is shared state is why you can't naively have a go channel that spans a cluster but Erlang's "actor" system works just fine over a network and the safety systems (nodedowns, monitors etc) are a simple layer on top.

kbolino10mo ago

You don't have to close a channel in Go and in many cases you actually shouldn't.

Even if you choose to close a channel because it's useful to you, it's not necessarily shared state. In a lot of cases, closing a channel behaves just like a message in its queue.

aatd8610mo ago

Isn't entanglement in quantum physics the manifestation of shared state? tongue-in-cheek

psychoslave10mo ago

Maybe. Or maybe we observe the same point of information source from two points which happen to be distant in the 3-coordinates we are accustomized to deal with, but both close to this single point in some other.

aatd8610mo ago

but that still means that there is shared state on the projection from the higher tensor space.

orthogonality needs to be valid for all subspaces.

j / k navigate · click thread line to collapse

0 pointstombert10mo ago0 comments

Yeah, similarly, Joe Armstrong (RIP), co-creator of Erlang explained it to me like this:

He wrote this to me in 2014, and it has really informed how I think about these things.

0 comments

throwawaymaths10mo ago

The thing is that go channels themselves are shared state (if the owner closes the channel and a client tries to write you're not gonna have a good time)! Erlang message boxes are not.

tombertOP10mo ago

Kubuxu10mo ago

You can think of closing the channel as sending a message “there will be no further messages”, the panic on write is enforcement of that contract.

Additionally the safe way to use closing of a channel is the writer closing it. If you have multiple writers, you have to either synchronise them, or don’t close the channel.

throwawaymaths10mo ago

kbolino10mo ago

You don't have to close a channel in Go and in many cases you actually shouldn't.

Even if you choose to close a channel because it's useful to you, it's not necessarily shared state. In a lot of cases, closing a channel behaves just like a message in its queue.

aatd8610mo ago

Isn't entanglement in quantum physics the manifestation of shared state? tongue-in-cheek

psychoslave10mo ago

aatd8610mo ago

but that still means that there is shared state on the projection from the higher tensor space.

orthogonality needs to be valid for all subspaces.

j / k navigate · click thread line to collapse