what happens when you hit the subrequest limit, does fetch throw an error? - Cloudflare Developers

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Sheng

S

Sheng•5/10/24, 12:26 PM

I don't think I hit any limit, because this error usually is the first request of the day / first request after deploy new version to CF worker, and the status 500 is coming from mailchannels api

Sheng

SSheng I don't think I hit any limit, because this error usually is the first request o...

johtso

J

johtsoOP•5/10/24, 12:28 PM

sorry, that wasn't in response to you, was an unrelated question

johtso

Jjohtso what happens when you hit the subrequest limit, does fetch throw an error?

kian

K

kian•5/10/24, 12:40 PM

Yes

kian

K

kian•5/10/24, 12:41 PM

So subrequests work in two ways - there are in-house subrequests, and everything else.

kian

K

kian•5/10/24, 12:41 PM

They have separate counters, separate 'buckets'

kian

K

kian•5/10/24, 12:41 PM

You can (on a paid plan) make 1000 subrequests with something like fetch(url)fetch(url), and another 1000 to in-house things (KV, R2, DO, D1, you get the idea)

kian

K

kian•5/10/24, 12:41 PM

Once you hit that limit, they throw a "subrequest limit exceeded" exception

johtso

J

johtsoOP•5/10/24, 12:55 PM

@kian thanks for clarifying!

johtso

J

johtsoOP•5/10/24, 12:56 PM

still not entirely sure how to deal with these limits when I'm doing work that requires making a lot of requests

johtso

J

johtsoOP•5/10/24, 1:10 PM

My instinct is to catch that error at a high level, and then schedule an immediate alarm

johtso

J

johtsoOP•5/10/24, 1:11 PM

Scheduling an alarm doesn't count as a request does it?

johtso

J

johtsoOP•5/10/24, 1:13 PM

Ah yes, they're transactional storage API operations, that's good

johtso

J

johtsoOP•5/10/24, 1:21 PM

@kian is there anywhere I can see exactly how to catch that exception?

kian

K

kian•5/10/24, 1:23 PM

Just a normal try/catchtry/catch around the subrequest

kian

Kkian Just a normal `try/catch` around the subrequest

johtso

J

johtsoOP•5/10/24, 1:54 PM

but how to I check if an error is a "subrequest limit exceeded" exception? is that the exact name of the exception? e.name === "subrequest limit exceeded"e.name === "subrequest limit exceeded"?

Sheng

SSheng Mailchannels + CF Workers, anyone facing status 500 error, EOF when sending emai...

James

J

James•5/10/24, 1:57 PM

Sadly not a direct solution to your problem, but I would recommend you avoid MailChannels. Cloudflare's continued partnership with them is very disappointing after their security issues and terrible response. See https://canary.discord.com/channels/595317990191398933/779390076219686943/1226529017763463219 for more details.

johtso

Jjohtso but how to I check if an error is a "subrequest limit exceeded" exception? is th...

kian

K

kian•5/10/24, 1:58 PM

export default {
  async fetch() {
    try {
      while (true) { await fetch("https://cloudflare.com/cdn-cgi/trace") }
    } catch (e) {
      return new Response(JSON.stringify(e, Object.getOwnPropertyNames(e)))
    }
  },
};

export default {
  async fetch() {
    try {
      while (true) { await fetch("https://cloudflare.com/cdn-cgi/trace") }
    } catch (e) {
      return new Response(JSON.stringify(e, Object.getOwnPropertyNames(e)))
    }
  },
};

kian

K

kian•5/10/24, 1:58 PM

You can test it with that and see what the error is

kian

Kkian ```js export default { async fetch() { try { while (true) { await fe...

johtso

J

johtsoOP•5/10/24, 1:59 PM

I'm guessing it's along the lines of this? https://github.com/cloudflare/miniflare/blob/c2ed3afdc1fed9f78d5cb6c50edc793a9a43a850/packages/shared/src/context.ts#L149

johtso

J

johtsoOP•5/10/24, 2:00 PM

which doesn't seem very amenable to being handled specifically

johtso

J

johtsoOP•5/10/24, 2:01 PM

Is this just the javascript way? generic errors with error text?

johtso

J

johtsoOP•5/10/24, 2:01 PM

coming from python I'm used to specific subclasses of errors

James

J

James•5/10/24, 2:02 PM

You absolutely can create subclasses of errors in JS, and attach things like a

code

code

, etc. but not everything does, sadly

johtso

J

johtsoOP•5/10/24, 2:03 PM

would be nice if core cloudflare errors did this :/

johtso

J

johtsoOP•5/10/24, 2:10 PM

{"stack":"Error: Too many subrequests.\n    at Object.fetch (worker.js:15:28)","message":"Too many subrequests."}

{"stack":"Error: Too many subrequests.\n    at Object.fetch (worker.js:15:28)","message":"Too many subrequests."}

johtso

J

johtsoOP•5/10/24, 2:19 PM

and this is going to behave differently when ran locally?

johtso

J

johtsoOP•5/10/24, 2:20 PM

@kian and do you think I can safely run that snippet locally, or will I end up spamming cloudflare?

johtso

J

johtsoOP•5/10/24, 2:24 PM

I don't think local wrangler is respecting subrequest limits..

johtso

J

johtsoOP•5/10/24, 2:51 PM

should I be able to test locally with the same subrequest limit behaviour? the github issues I'm seeing give the impression that it should "just work"

James

J

James•5/10/24, 5:34 PM

I don't believe subrequest limits are enforced at all locally

James

J

James•5/10/24, 5:35 PM

so that'll probably just run forever

johtso

J

johtsoOP•5/10/24, 6:29 PM

@James that seems unfortunate? something can seem to run fine locally and then break when deployed

James

J

James•5/10/24, 6:29 PM

I agree, it's very much not ideal

James

J

James•5/10/24, 6:29 PM

https://github.com/cloudflare/workers-sdk/issues/4359 seems to be where this is tracked if you want to add your thoughts

johtso

J

johtsoOP•5/10/24, 6:30 PM

https://github.com/cloudflare/workerd/blob/a3de83cbbd338bb64f9782f3584ec17ad6995821/src/workerd/io/limit-enforcer.h#L84

johtso

J

johtsoOP•5/10/24, 6:30 PM

is this not being used when running locally?

johtso

J

johtsoOP•5/10/24, 6:30 PM

oh right, workerd is the production runtime, but also used locally

Walshy

W

Walshy•5/10/24, 6:31 PM

that is local but the implementation is internal, that's just the header file

Walshy

W

Walshy•5/10/24, 6:34 PM

how come you're doing 1k subrequests?

codebam

C

codebam•5/10/24, 6:53 PM

did cloudflare AI just go down? I didn't change any code and I'm getting Error: AiError: undefined: ERROR 3040: Unknown internal errorError: AiError: undefined: ERROR 3040: Unknown internal error

Walshy

W

Walshy•5/10/24, 6:54 PM

https://canary.discord.com/channels/595317990191398933/895794943182909470/1238495826683101194

Walshy

WWalshy https://canary.discord.com/channels/595317990191398933/895794943182909470/123849...

codebam

C

codebam•5/10/24, 6:55 PM

thanks

Walshy

WWalshy how come you're doing 1k subrequests?

johtso

J

johtsoOP•5/10/24, 7:17 PM

I'm mirroring data to my d1 database from an api that only allows requesting one thing at a time

Walshy

W

Walshy•5/10/24, 7:18 PM

i'd submit to a queue and process in a queue

Walshy

WWalshy i'd submit to a queue and process in a queue

johtso

J

johtsoOP•5/10/24, 7:25 PM

just seems a bit overkill.. I don't even want parallelism because I don't want to overload my API

johtso

J

johtsoOP•5/10/24, 7:26 PM

and I don't really need a concept of a "job" or queue item because anything not already in my database is something that still needs to be fetched

johtso

J

johtsoOP•5/10/24, 7:26 PM

alternatively I was thinking I might just run the "backfilling" as a local process on my computer

johtso

J

johtsoOP•5/10/24, 7:27 PM

as it's quite different from the work of constantly monitoring for new data (which should only involve a few requests)

liam | helius.dev

L

liam | helius.dev•5/10/24, 10:32 PM

Is anyone using workers to proxy websockets getting 502 errors currently? Suddenly all our websockets, across multiple accounts, stopped working

liam | helius.dev

Lliam | helius.dev Is anyone using workers to proxy websockets getting 502 errors currently? Sudden...

Walshy

W

Walshy•5/10/24, 10:53 PM

Hey, got a repro URL? and is this fully client <-> Worker or is there an origin involved?

export default {
  async fetch() {
    try {
      while (true) { await fetch("https://cloudflare.com/cdn-cgi/trace") }
    } catch (e) {
      return new Response(JSON.stringify(e, Object.getOwnPropertyNames(e)))
    }
  },
};

export default {
  async fetch() {
    try {
      while (true) { await fetch("https://cloudflare.com/cdn-cgi/trace") }
    } catch (e) {
      return new Response(JSON.stringify(e, Object.getOwnPropertyNames(e)))
    }
  },
};