processor core pegged to 100% at (randomly) doing line plot but only with BitMapBackend

[themzlab]

I found a workaround for my problem: simply switch to SVGBackend. I am using Raspberry Pi computers based on CM4 module and with a 64-bit image of Raspberry pi OS. I am doing a pretty basic line plot with two series. My machines make a new plot every 5 minutes. The function appeared ok until I noticed that occasionally one cpu core would be pegged at 100%. I logged the information with a bash script and found it would be this way for 8-9 minutes in the occasion it happened.

Later, I added Rust code to time how long it took to generate the plots and also made a switch in my code to load one backend or the other and this confirmed that i could break the machine or correct it depending on the backend. My module does not crash/panic as far as I know because the machine does keep operating. what I found is that the plot generation command in Rust would take 8-9 minutes! instead of a fraction of a second and that matches what I see for cpu usage.

In the end my solution is to use the SVG backend to create that file and then I use a library called Cairo and python bindings to convert the svg to a png for use in my program.

plotters is a black box to me, so I didn't know how to do any more troubleshooting. I am just putting this here as fyi I guess.

plotters = "0.3.5"
rustc 1.74.1 (a28077b28 2023-12-04)
Python 3.9.2
UsingPy03 to create Rust modules for Python