Ui-control possible memory leak

[Gaetano]

I use Dashboard 2 under NodeRed 4.0.2.
I use ui-control to go to a specific page.

My syslog has many lines produced every time ui-control is used.

The syslog lines are as follows:

2024-09-07T13:47:36.641313+02:00 PI4bOpenVPN Node-RED[1245]: 7 Sep 13:47:36 - [info] [ui-base:My Dashboard] Disconnected qa_VLuMd2wRUj_SPAABK due to transport close
2024-09-07T13:47:36.900614+02:00 PI4bOpenVPN Node-RED[1245]: (node:1245) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 disconnect listeners added to [Socket]. MaxListeners is 10. Use emitter.setMaxListeners() to increase limit
2024-09-07T13:47:36.900909+02:00 PI4bOpenVPN Node-RED[1245]: (node:1245) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 ui-control listeners added to [Socket]. MaxListeners is 10. Use emitter.setMaxListeners() to increase limit

I think the limit of 10 MaxListeners is too low, but I think it should be evaluated better by FlowFuse.

Thanks, bye

[Gaetano]

Sorry to insist but the problem could be important.
Can I have some feedback on my post?
Thanks a lot, bye!

[Steve-Mcl]

Hi @Gaetano, it is likely down to how many nodes are in use (i.e. it is not spiralling away).

Please raise this as a new issue on the dashboard repository so that it can be tracked and not forgotten or lost in a forum thread.

Please include info like the dashboard version, how many ui-control nodes you have, how and when the log event happens (i.e. on node-red start up, when you deploy changes to Node-RED, every time you page change in the dashboard, every time you refresh the dashboard, every time a new browser connects to the dashboard etc) - that will help us pin it down.

Thanks.

[Gaetano]

Steve,
thank you for your reply.

I use NodeRed 4.0.2 on Raspberry PI 4b (4 GB RAM, free 400 KB) with Raspbian 6.6.47. Number of nodes is about 80.
Dashboard 2 version 1.16.0.
NodeJS version 20.17.0

ui-control is used only in 4 places:
3 of them directly in flows
1 in a subflow (named "Trigger-DB2") that is used to refresh a page on the browser and to trigger a flow. See the content of subflow:

The number of instances of this subflow is 15.

The content of ui-ctrl-db2 is:

I obtain the message on syslog each time I use ui-control. For example, if I do a refresh on this page (but the message is presented on all pages):

On syslog I see:

2024-09-10T08:01:34.754384+02:00 PI4bOpenVPN Node-RED[502]: 10 Sep 08:01:34 - [info] [ui-base:My Dashboard] Disconnected IpwNNDsYi01xHTbzAACd due to transport close
2024-09-10T08:01:34.955434+02:00 PI4bOpenVPN Node-RED[502]: (node:502) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 disconnect listeners added to [Socket]. MaxListeners is 10. Use emitter.setMaxListeners() to increase limit
2024-09-10T08:01:34.955830+02:00 PI4bOpenVPN Node-RED[502]: (node:502) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 ui-control listeners added to [Socket]. MaxListeners is 10. Use emitter.setMaxListeners() to increase limit

The NodeRed flow that is under "Soglia Attuale" of the page is:

If you need other information, don't hesitate to ask me.

Ciao!