[BUG] possible memory leak to modbus tcp write

[mcmilleraltronic]

Describe the bug
after roughly 8 hours of running on a CM4, the memory of a process named "node main.js" went from almost no memory usage to taking up ~1gb of memory usage on a 2gb max, causing the system to crash.

To Reproduce
Steps to reproduce the behavior:
See the images and script below, writing values in the script to the "modbusTOde' is where the issue appears to be.

Expected behavior
I would expect FUXA to handle the writes without crashing.

Screenshots

Example project
FUXA_WH_16OCT2025_rev0.json

Environment

• FUXA version: 1.2.5-2292
• Node.js version: 20.15.1
• npm version: 10.7.0
• Platform/OS: Debian GNU/linux 12
• Browser: chromium 125.0.6422.133

fuxa187.log

modbus_forward_script.txt

[unocelli]

@mcmilleraltronic Thanks for reporting this!

From a first look at your project, it seems the issue might also be related to resource overload rather than a direct memory leak.
I noticed that the script in your project runs every 0.5 seconds, and inside it there are about 120 system calls ($getTag / $setTag) - including 58 $setTag writes to the PLC on each cycle.
In addition, you have 4 Modbus devices with a 1 second polling rate, and 2 devices polling every 200 ms, each with roughly 30 tags.
This combination means that multiple write and read cycles may overlap before the previous one has completed, which can cause growing memory usage or pending promises accumulating over time.

You could try: increasing the script interval (e.g. 2–5 seconds), or reducing the polling frequency of some devices, to see if the memory usage stabilizes.

[mcmilleraltronic]

@unocelli that makes a lot of sense, I will tweak my timings and see if can get it stabilized. I will update with my findings.