Issue with timerng - lua udp socket read timed out

[martin-gg]

Hello,

I hope you are doing well.

I have an OpenResty implementation feature that is used as a counter via a timerng object. The code related to the functionality that is being used is the following:
local timer_module = require("resty.timerng")
local timer_sys = timer_module.new({restart_thread_after_runs = 1000}) -- restart_thread_after_runs was added after the problem started
[. . .] -- unrelated other nginx code
timer_sys:start()
timer_sys:named_every(key, 1, function_new)

After about an hour of execution, we are seeing the following logs:
2024/07/26 09:03:08 [error] 1771830#1771830: *1339053 lua udp socket read timed out, client: [IP], server: , request: "GET [Request_URI] HTTP/2.0", host: "[host]"

Have you ever encountered an issue similar to that one and what would be a possible solution?

[ADD-SP]

Hi @martin-gg, do you have steps for reproducing this issue?

[martin-gg]

Hi, thank you for the fast response and apologies for the delay.

It happens randomly, usually after about an hour. The way the Lua script is triggered is by hitting an URL with a specific query string, pretty standard stuff. From there on, there is an a content_by_lua_file directive which starts the handling script.

The code itself is present in the opening post, the [...] part is another lua extension which then runs a shell command on a Linux system (Rocky Linux 8 if this would be of any help). Since the log message mentions UDP sockets, I checked if the UDP connections have reached a certain limit, but they were in the 100-200 range. The issue is resolved once Openresty is restarted, however in this case the URL has to be accessed again to trigger the script, which is not sufficient, since the plan is to use an automated cURL request from a 3rd party VM.