Very slow app response times

Hello,

Server response times from my app are around 4s.
I verified it using chrome dev tools as well as curl.

This happens only from my home, as I tried from curl’ing from hetzner vm and it was acceptable - between 50 up to 500ms.

I am even querying fly.io domain directcly skipping cloudflare which is normally sitting behind my app, just to make sure that this isn’t cloudflare problem.

It’s not a random accident - over last few weeks I noticed that periodically response times are geting very slow (2-5s) and the other time they are simillar to the ones from the remote VM (50-500ms).

During the slowdown period other websites / services respond normally, there are no slowdowns to be found. I even tried deployting same app behind nginx on hetzner vm and haven’t notied such issue.

Region of my app is the same city as I live and hetzner’ VM is in germany - I would expect response times to be much lower from my home.

It’s a go app using sqlite deployed on the smallest fly instance. Ram usage below 40% all the time. No cpu spikes at all.

According to the app and the fly grafana response times from the app are at most 2ms.
I also checked the fly proxy tab in grafana and p95 are under 5ms.

At this point I have no idea how to debug this issue - any suggestions?

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Added machines

If it’s not a memory issue then ISP routing might be the culprit. Do a traceroute debug.fly.dev to see if you’re getting bounced around.

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Thanks for the suggestion, I checked that and it’s seems that when there is the issue with long response time from the app traceroute is showing 255+ hops for some reason, while azure VM in my home city show up to 10 hops. Looks like an ISP issue then?

Or a fly routing issue. There’s been a dozen or more people with your issue. Try emailing support if you didn’t get a dev response here.

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