Yes it will, at around 1k websockets, the connections start to "break" randomly closing with 1006 close codes. And imagine you had a million websockets, the array would have a million elements and iterating over an array of a million elements takes a loooong time so this single durable object approach isn't scalable at all

sounds like a network connection limit.... can you shard them in some way maybe? or could you perhaps access a durable object from within a durable object?

That's what I want to do, shard the connections across multiple durable objects so those limits aren't hit but then doing things like broadcasting something to all connections would become impossible since there is no way to do this currently with durable objects afaik

I wonder if you can access a durable object from within a durable object?

Yes you can

How would that help solve this though?

you could drop your websockets into buckets so they are handled by separate threads

so you could shard them into buckets of 100 (or whatever)

and then just iterate through the buckets from the parent

Master DO -> Bucket DO (1-X) -> Connections if someone posts a message it would get passed up to the master and spread out

the connects between Master DO and Bucket DO's can just use the standard connections, I don't think they would need to use websockets...

then each Bucket DO is only iterating over 100 (or whatever number you choose) connections

That sounds great, I'm worried this will hit the subrequests hard limit of 50 since you'd be sending a request to all the bucket DO's

instead of mainting a number you could use some systematic way of bucketing connections (i.e. hasing the usernames and using the first two letter of the hash, or whatever)

oh right... didn't they just increase that limit though?

but yeah you might be stuck at 50 buckets for now

The website https://developers.cloudflare.com/workers/platform/limits says 50, hopefully it will be increased in the future or maybe they can provide some way of doing all this without having to make subrequests

yeah totes

That limit is for outbound HTTP requests. Durable Object stub requests have a different limit.

it's 1000 iirc

The limit increase from 50 subrequests to 1000 can be found in the release notes: https://community.cloudflare.com/t/2021-7-16-workers-runtime-release-notes/287327

@Brizy super interesting stuff. Thanks for sharing your issues! Please keep us posted about your progress on this, I'm also working on solving a similar issue of scaling wbesockets. Knowing these limits that you posted is super useful, if you have more details on this would love to hear about them too!

DurableObjectState.id.name

from within the durable object's fetch doesnt seem to return the name that was used to create the durable object, is this intentional?

idFromName()

is actually just a hashing function, so the DO has no way of knowing the name used. You'd have to pass it to the DO in a request.

You can do this with a parameter or a header, or you could set it as the hostname if it does not include invalid characters.

hostname is actually a nice one, haven't thought about that.

It also makes it easy to see which DO the request is going to when using

wrangler tail -f pretty

😛

speaking of URLs in DO requests, you can modify pretty much every part of it as long as it conforms to the URI spec

so something like

GET user://username/posts/1

is possible, if you want

For sure, I'll keep you posted