[Bug]: `MaxListenersExceededWarning` when using newer AWS SDK version

[peter-asztalos-mf]

[Bug]: `MaxListenersExceededWarning` when using newer AWS SDK version

[erichkuba]

I've possibly been able to resolve this by pinning the @smithy/node-http-handler package (which is used internally by @AWS-SDK) to version 3.0.1

With this, I have been able to upgrade the @AWS-SDK packages to version ^3.600.0. This is not a long-term solution but provides a bridging solution until the root cause is addressed.

So, in short, add the following to your dependencies in your package.json file:

    "@smithy/node-http-handler": "3.0.1",

I've deployed this change into our systems and will monitor memory usage over the next few days, but the warning no longer presents.

I hope this is helpful.

[erichkuba]

After reviewing the impact of the above fix, it does appear that the leak has been resolved, so I'm happy to recommend it as a temporary solution until a more permanent fix is available.

[nicholasgriffintn]

Hey, thanks for raising an issue.

3.6 of the sdk would be a major version, we don't naturally support major version releases as they come out as they come with breaking changes like this.

It would be something that we'd have to look at for our next major/minor release ourselves.

I am rather busy at the moment though, so I would suggest staying on 3.5 for a little while longer.

We'd be happy to take a pr though if this is an issue for anyone.

[peter-asztalos-mf]

Hej, thanks for the quick response.

I can reproduce this issue just upgrading to 3.582.0 which if I understood correctly is part of 3.5, right? 🤔

I can look into it and open a PR. My fix during the test was very simple: passing new AbortController per request. Do you see any issue with that?

[nicholasgriffintn]

Ahh sorry, I thought you said it was 3.6, the pr you linked also seems like a breaking change to me.

If I have time I might be able to look into it. In terms of a possible solution, that might be if, I've not looked too deep though.

[erichkuba]

I'm having the same issue and can confirm that this is not just a warning but continues to leak until the process is out of memory.

[nicholasgriffintn]

If I have spare time this week I'll take a look, unfortunately, until then, I'd have to ask that everyone bares with.

If anyone has the time themselves to look, that'd be super helpful, but if not, you'll have to wait on me. Unfortunately, it has come at a particularly busy time for the BBC.

[nicholasgriffintn]

Awesome! So it is a change in the next version that causes the issue, that makes it easier to figure out what's going on, thanks!

(This one: https://github.com/smithy-lang/smithy-typescript/releases/tag/%40smithy/node-http-handler%403.1.0 which is the change mentioned at the top, spot on!)

[nicholasgriffintn]

On further research, this may be because the Aborts are not automatically being cleaned up, there's an old Node issue around this: nodejs/node#46525

Possibly because smithy is adding event listeners: https://github.com/smithy-lang/smithy-typescript/pull/1308/files#diff-98216b22e6b39a1cd6f2ab013304d4964152b554c4ad8fee4182a961b42285d8R192 but not removing them?

Update: I've opened an issue around this here: smithy-lang/smithy-typescript#1318

[nicholasgriffintn]

Update on this, I have published 11.0.0-canary.1 with the latest version of the aws-sdk to test this with that new version and I've made a new example that sets up Docker with localstack for a truer test: https://github.com/bbc/sqs-consumer-starter/tree/main/examples/docker

With this, I have replicated the issue:

Still trying to figure out the best way to resolve it though.

[joseamt]

@erichkuba Still I have the issue.

Node version : 18.20.2
"@aws-sdk/client-sqs": "^3.600.0",
"@ssut/nestjs-sqs": "^2.1.0",

I tried with @smithy/node-http-handler package and still the issue persists.

[nicholasgriffintn]

Hey, I'm still waiting on a response from AWS on the issue I raised above.

Outside of that, the current suggestion is to do what was described here: #500 (comment), or pin your AWS SDK version to before this change.

Outside of that, if anyone has any ideas for how it might be resolved in SQS Consumer, feel free to open a PR, we are in an election period at the moment, so I'm strapped for time.

Could we avoid adding "me too" comments though please? This just fills up the thread and makes it unreadable for other people coming in.