Answer process jumps after few days to ~ 99% CPU usage

[brocaar]

Describe the bug

After leaving Answer for some time (days?) running, the CPU usage jumps and stays at around 99%, even when it is not serving any requests. The web-interface is still responsive enough to keep it functional, but after a restart (I have to kill the process) it hardly consumes any CPU.

To Reproduce

I'm not sure how to reproduce / trigger this. It happens after a couple of days running. I noticed web-requests take slightly longer and I inspected the CPU usage. This already happened a few times in a row.

Expected behavior

CPU usage stays stable.

Logs

Feb 02 10:32:48 chirpstack-support answer[2067003]: 2026-02-02 10:32:48.045        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""
Feb 02 10:32:48 chirpstack-support answer[2067003]: 2026-02-02 10:32:48.288        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""
Feb 02 10:32:48 chirpstack-support answer[2067003]: 2026-02-02 10:32:48.429        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""
Feb 02 10:36:25 chirpstack-support answer[2067003]: 2026-02-02 10:36:25.605        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""
Feb 02 10:36:25 chirpstack-support answer[2067003]: 2026-02-02 10:36:25.767        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""
Feb 02 10:40:00 chirpstack-support answer[2067003]: 2026-02-02 10:40:00.025        INFO        cron/cron.go:88        checking expired user suspensions
Feb 02 10:45:16 chirpstack-support answer[2067003]: 2026-02-02 10:45:16.946        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""
Feb 02 10:45:31 chirpstack-support answer[2067003]: 2026-02-02 10:45:31.729        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""
Feb 02 10:45:31 chirpstack-support answer[2067003]: 2026-02-02 10:45:31.870        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""
Feb 02 10:45:32 chirpstack-support answer[2067003]: 2026-02-02 10:45:32.032        ERROR        activity_common/vote.go:60        pq: invalid input syntax for type bigint: ""

There is nothing special in the logs. I will restart the process with LOG_LEVEL=DEBUG to gather more log-output.

Plugins

Platform

• OS: Linux AMD64
• Version: v1.7.1

[LinkinStars]

@brocaar Alright, if any additional error logs appear, please provide them to us. Then, please share the list of plugins you're currently using, and we'll continue to follow up on this issue.

[brocaar]

@LinkinStars, will do. I just restarted the process with DEBUG logging. It is now running at ~ 1% CPU as it should. Once it starts spiking again, I'll let you know.

[brocaar]

@LinkinStars it is back at 99% CPU. However, I can not find anything in the logs that might point to the cause....

The only additional logs I see with DEBUG are:

DEBUG        router/ui.go:68        open static path build/static/js/ .....

and

DEBUG        rank/rank_service.go:255        user XXX want to do action ....

I see you released a v2, which also solves two other issues that I reported. I will try upgrade to that version and continue my testing.

From the logs, I see there is a kind of cron scheduler that schedules periodic tasks. I have not looked at the implementation, but could it be that one of these tasks gets stuck, keeps retrying, then the scheduler schedules a new duplicate cron task meaning that there are now two tasks retrying, shortly after three and so on...?