Arduino GUI consumes CPU when serial monitor is opened while board is unattached

dma_k · August 10, 2019, 10:37pm

Dear all,

I have noticed the following misbehaviour of Arduino GUI v1.8.9. I am monitoring the messages produced by my board Arduino Nano (ATmega328P) using “Serial Monitor”.

Once the board is disconnected (USB is unattached) Arduino GUI starts to consume CPU. Not much, but greedy enough to force CPU fan to rotate faster. If I close “Serial Monitor” window, Arduino GUI is OK again.

Does somebody observe the same problem?

pert · August 11, 2019, 12:04am

This is a known bug:

github.com/arduino/Arduino

Disconnecting USB causes IDE to use 100% CPU on Linux

opened 05:48AM - 27 Sep 14 UTC

closed 08:15AM - 18 Jul 19 UTC

nickgammon

Component: IDE OS: Linux Type: Bug

On the Ubuntu version of the Arduino IDE 1.0.5, disconnecting (unplugging) the …USB cable from the PC to the Arduino Uno causes CPU usage for the Java IDE runtime to jump to 100%. What is it doing? Code: ``` top - 09:43:14 up 1 day, 23:54, 4 users, load average: 0.71, 0.60, 0.60 Tasks: 246 total, 1 running, 244 sleeping, 0 stopped, 1 zombie %Cpu(s): 8.8 us, 5.7 sy, 0.0 ni, 85.5 id, 0.1 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 16376056 total, 16104688 used, 271368 free, 641840 buffers KiB Swap: 31249404 total, 0 used, 31249404 free. 9019168 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2142 nick 20 0 6874812 163476 25408 S 100.1 1.0 0:27.44 java ^^^^^ ``` Steps to reproduce: - Compile and upload Blink sketch - Open Serial monitor - Run the "top" command in a console window - Unplug the USB cable from the Arduino - Note that the java process CPU climbs from around 7% to 100%

It has already been fixed, but there has not been a production release of the Arduino IDE since that time. If you want to test the fix, you can try using the hourly build of the Arduino IDE:

system · May 5, 2021, 4:23pm