ARTICLE AD BOX
I'm running into a frustrating issue with a Promise.all chain in Node.js when trying to execute several data-fetching tasks concurrently.
My setup involves a few asynchronous API calls. To make sure my app is aware of potential external issues before starting the main logic, I've added an initial network availability check (a simple fetch or axios.get) on a known monitoring endpoint.
The problem is that if the initial network check targets a specific kind of internal monitoring URL, the entire Promise.all seems to hang indefinitely if that network check fails or times out (even with a defined timeout on the fetch call). If I swap the check URL for something generic like google.com, the rest of the promises run correctly, regardless of the check result.
This is the general structure of my code (simplified):
JavaScript
const monitoringCheck = () => { const checkUrl = 'https://some-internal-api/status'; // The URL causing the issue // The goal is to see if the monitoring system is down/slow return fetch(checkUrl, { timeout: 5000 }) .then(response => response.ok) .catch(error => { console.error("Monitoring check failed:", error); return false; // Crucially, I want this to resolve to 'false' if it fails }); }; const fetchData1 = () => { /* ... returns a promise ... */ }; const fetchData2 = () => { /* ... returns a promise ... */ }; Promise.all([ monitoringCheck(), fetchData1(), fetchData2() ]) .then(([isMonitoringUp, data1, data2]) => { if (!isMonitoringUp) { console.log("Monitoring system seems down. Proceeding with caution."); } // Process data1 and data2 console.log("All data processed."); }) .catch(err => { console.error("A critical promise failed:", err); });What I've tried:
Wrapping the monitoringCheck in a Promise.race with a manual timeout—no change.
Ensuring the catch block in monitoringCheck always resolves, even on error.
I suspect it might be something specific about how Node/OS handles a failed connection to certain types of endpoints (maybe an SSL/TLS handshake issue, or a routing block). For example, I've seen similar deep network issues discussed when users are trying to diagnose network outages like those tracked on sites like spectrumoutage.org – sometimes the problem is subtle and local, not a simple 404.
The Question:
Why would one specific internal URL cause a silent, non-failing hang across the entire Promise.all chain when its promise is explicitly set to resolve (to false) within its own .catch() block, and how can I reliably force it to resolve and allow the rest of the promises to continue?
