Currently, an open workspace page uses 2 server side event (SSE) connections. These connections remains open as long as the page is open.

Google Chrome only supports a maximum of 6 open connections per host.

Firefox also has a limit, but for whatever reason, the SSE endpoints fail on Firefox. So on firefox, we do not hit the concurrent connection limit.

You cannot reproduce this on https://dev.coder.com because (for w/e reason), all requests uses HTTP2. So there must be some multiplexing/connection pooling going on by Chrome.

I also tested this through a cloudflare tunnel, which uses HTTP3 and also does not have the issue.

Reproducing

1. To reproduce, you must be using HTTP 1.1 from Chrome.
2. Open a running workspace page on 4 tabs
3. Open on a fourth tab, and the web request will be stuck in "pending" forever.

Workaround

A current workaround is to use a reverse proxy in front of Coder that enables HTTP2. Or you can enable TLS on the Coder server (--tls-enable). Golang serves HTTP2 on TLS servers by default.

Implementation Notes

The easiest solution would just be to support HTTP2 on non-TLS connections in Coder. We explicitly opt in for TLS serving here:

HTTP2 does not work over non-tls.

Solution suggestion is to implement something in the frontend to detect HTTP 1.1 vs HTTP2.0 and display a warning?