Slow browsing on http2 enabled reverse proxy (apache2), long-polling `/user/events` blocks other requests

[sub0ne]

I currently have the following setup

• gitea 1.16.5
• mysql 8.0.28
• apache 2.4.38
• gitea ssl is disabled
• apache does forward http to https
• apache is configured to reverse proxy to gitea
• Google Chrome shows that all requests are done via h2

When I navigate the files of any of my repository and do "fast directory browsing" (e.g. folder A -> folder B -> up to folder A -> folder B). Something is getting hiccups and I get requests which take about 10 seconds before the folder content is displayed. Those 10 seconds are pretty constant and can be seen in the apaches logs as follow:

2022/03/29 13:56:24 Completed GET /user/events 200 OK in 10.003202925s

I spend hours trying to track this down to what the problem is, and finally I found that adding Protocols http/1.1 to the VirtualDirectory of my apache configuration seems to fix this problem. Pretty fast browsing with low requests roundtrips.

Is this problem known? What logs can I provide else?

[wxiaoguang]

/user/events is a long-polling end point. The log is changed in 1.17, if you don't like the log, use 1.17 instead.

[wxiaoguang]

Hmm ..... /user/events is a long-polling end point.

If "I get requests which take about 10 seconds before the folder content is displayed." is the case, I think it may be caused by http2's muxing ........

Indeed the long-polling seems not friendly to http2, it should be replaced by websocket

[gertvdijk]

Same issue here; thanks for the hint about HTTP/2. I can confirm that only enabling HTTP/1.1 on the public side of the Apache httpd fixes it. It looks like some concurrency issue with Apache. While using the Event worker MPM one should get 25 concurrent connections to the backends and this should not be an issue with just one user and one browser, I think. But it does block a lot.

Moved to nginx with HTTP/2 enabled and did not experience any issue.

[samangh]

I have the same issue, when using an Apache as a proxy. I can confirm that disabling HTTP/2 on the Apache config fixes this issue.