WebSocket API Gateway `PostToConnection` command seemingly hangs forever

[crispyricepc]

Checkboxes for prior research

• I've gone through Developer Guide and API reference
• I've checked AWS Forums and StackOverflow.
• I've searched for previous similar issues and didn't find any solution.

Describe the bug

When calling PostToConnection to an endpoint that might not respond, no timeout is used even if one is set.

Regression Issue

• Select this option if this issue appears to be a regression.

SDK version number

@aws-sdk/client-apigatewaymanagementapi v3.965.0

Which JavaScript Runtime is this issue in?

Node.js

Details of the browser/Node.js/ReactNative version

v24.11.1

Reproduction Steps

Timeout appears to be ignored, which was observed in #6896 but closed prematurely.

Simple slow-responding server PoC

import express from "express";

const app = express();
const PORT = 3000;

async function response(req, res) {
  // Respond slowly
  await new Promise((resolve) => setTimeout(resolve, 10_000));
  res.send("hello");
}

app.use(response);

app.listen(PORT, (err) => {
  if (err) {
    console.error(err);
    return;
  }

  console.log(`Listening on port ${PORT}`);
});

Try to access this endpoint with a short timeout set

import {
  ApiGatewayManagementApiClient,
  PostToConnectionCommand,
} from "@aws-sdk/client-apigatewaymanagementapi";

const client = new ApiGatewayManagementApiClient({
  endpoint: "http://localhost:3000/",
  logger: console,
});

await client.send(
  new PostToConnectionCommand(
    {
      ConnectionId: "conn",
      Data: new TextEncoder().encode("hello"),
    },
    { requestTimeout: 5 }
  )
);

Observed Behavior

Process exited after 10 seconds

Expected Behavior

Process should have exited after 5 seconds (or 5 milliseconds, I couldn't find documentation on requestTimeout)

Possible Solution

No response

Additional Information/Context

No response

[crispyricepc]

Thought I would answer the question #6896 (comment) too, since when creating the PoC I did notice that postToConnection exists on the ApiGatewayManagementApi class too, as well as the standard send command that I used above. When using postToConnection I observed the same behaviour

[smilkuri]

Hi @crispyricepc,
It's recommended to use NodeHttpHandler for configuring timeouts in this scenario. See docs: https://github.com/aws/aws-sdk-js-v3/blob/main/supplemental-docs/CLIENTS.md#request-handler-requesthandler

[crispyricepc]

Understood, so the requestTimeout property doesn't do anything? Should it be removed?

[crispyricepc]

We actually noticed this line appearing a lot in our logs:

@smithy/node-http-handler:WARN - socket usage at capacity=50 and 532 additional requests are enqueued.

Which suggests that connections aren't being closed. Not sure what could be causing this though