Good morning fellow alchemists! I have a question about quite a low level implementation topic regarding copy/concurrency semantics, let me explain the situation briefly first: I have some (~10) ETS tables (set/unordered) that contain a few 100k records each, where the primary keys are either str…

As a start, do you want that cache to be multi-node or single-node?

In Rustler you can use resource/ResourceArc to pass a reference into Elixir code. The documentation is quite lacking, but you can look at this test . If you want to have mutable resource, you must manually synchronise on the Rust side. E.g. you can use RwLock, or an rcu. Beware, that resource refer…

single node, as in every node in the cluster has its own local cache, but every node in the cluster has the cache :slight_smile:

oh cool, that already helps a bit, thanks!

Resource references can be shared across nodes, but they can only be used (in a NIF) on the node that created them initially and only if it’s still alive when accessed. E.g. if you generate a resource object on your node from a process, send it to another node, let the process die and receive the an…

My Rust chops have eroded a little bit since I haven’t used it actively in like half a year now but last I remember I have used DashMap successfully before in an application that had a very heavy usage of read and write caching. It’s single-node. Sadly this was predating the times I became obsessed…

If you’re precomputing the data, you could look into using :persistent_term but I’m not sure the viability of updating that data, since you’d force a global GC on every update. How frequent are the updates?

Data is always passed by reference into NIFs as they run in the same process environment as the calling process this is hugely valuable information for me already, thanks for that! so this would solve part of my problem already, passing the data blob into rust for further computations is “free”! …

I have used DashMap successfully before in an application that had a very heavy usage of read and write caching. this looks nice indeed, but my problem around it is still: where to store that data in Elixir land? a GenServer afaik does not allow for truly concurrent reads

How frequent are the updates? unpredictable unfortunately - could be nothing for an hour but also some cronjob somewhere could trigger thousands of updates in a few seconds… also I think (mis-) using persistent term for that is kind of dirty, isn’t it?

Elixir Programming Language Forum

GenServer/ETS/Rustler performance questions

Questions & Help Questions

Hisako1337 June 27, 2024, 3:37pm 16

thanks @dimitarvp - will check this out, too!