Plot panel buffers data indefinitely by default for live connections

[jtbandes]

Current Experience
When using Plot with a live connection, the plot internally seems to buffer data indefinitely, and the app eventually slows down. As soon as the plot panel is removed, the app gets faster again.

cc @defunctzombie

Desired Experience
Maybe some combination of:

• having some max window size by default
• warning the user if they have no max window size and the connection is a live connection (or the plot seems to be gathering too much data)

[jhurliman]

Another option is to do something similar to what metrics-oriented TSDBs do and have time-based retention windows. Store up to N points for the last 1s, N points for the last 1m, N points for the last 1h, and N points for everything before the last hour for max memory usage of 4*N points. The downside of this approach is the scale of the retention windows makes assumptions about your data frequencies and the total time window you are observing.

[github-actions[bot]]

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[bertaveira]

We have had this issue. It is causing bit problems with our usage since after just 2min it starts getting slow. Even setting an X axis range does not change the fact. It still stores everything and get slow to the point where it refreshes every multiple seconds and becomes unresponsive.

Is there any plans to change this behaviour soon?

[defunctzombie]

We are aware of this and working on a fix. If you are using a websocket connection here's a preview deployment you can test: https://studio-hdnbgt93s.foxglove.party/ to see if it resolves your issue. 🙏

[bertaveira]

Thank you, it seems to improve significantly. I will continue testing it as new changes are made to the pull request

[defunctzombie]

The Plots! PR has merged which culls the accumulated data points during live playback.