PMM-QAN MongoDB - Errors - Explain plan not working

[kirangelli]

Hi @Ivan_Groenewold/Team

We are using PMM2 client version 2.29.1
PMM Server version 2.28.0

Currently, I am seeing the below errors with respect to pmm-agent service on the monitored mongoDB Instances.

Error 1:

couldn’t add document to aggregator agentID=/agent_id/5f4075d5-c97e-47a5-b042-3ae28084cbad component=agent-builtin type=qan_mongodb_profiler_agent

Error 2:

incomplete read of message header: context deadline exceeded: cannot explain this type of query. component=actions-runner id=/action_id/0577e31a-81d7-4acc-9220-98c49275b02c type=mongodb-explain
I see that the mongodb_exporter and mongodb_profiler_agent are in running state.

I am seeing these errors very often and I had to restart pmm-agent service to fix.
Even after the restart, the errors get appeared again after 1-2 hours.

How can we avoid these errors? Please help me out.

Thank you,
Kiran

[Jiri_Ctvrtka]

Hi Kiran, for error 2 I already replied to you in another thread. Here is ticket for it: [PMM-11185] QAN: Mongo explain doesnt work for queries with aggregation. - Percona JIRA. About error 1, please do you have any queries which causing this error? Or if you can share steps to reproduce? Thank you.

[kirangelli]

Hi @Jiri_Ctvrtka

Thank you for your response.
We were able to fix the errors after version upgrade of pmm2 client.
Current version of client and server are 2.32.0

Now, we are seeing different errors when we click on the Explain tab.

Attached the screenshot for reference.

Also, at times we observe that the data is not being collected by PMM in MongoDB Repl summary dashboard. We had to restart the pmm-agent to fix that.

Do we need any maintenance (service restart) to be taken care once we deploy PMM?

Please advise.

Thank you
Kiran