Lots of Serial Monitor content without line break causes IDE to become unresponsive

[per1234]

Describe the problem

If the Arduino board prints a large amount of data without a line break to Serial Monitor, the IDE becomes unresponsive.

To reproduce

Equipment

• Any Arduino board

Steps

1. Upload the following sketch to the Arduino board:

   void setup() {
     Serial.begin(115200);
   }
   void loop() {
     Serial.print("hello");
   }

2. Open the "Serial Monitor" view.
3. Select "115200 baud" from the dropdown baud rate menu at the top right corner of the "Serial Monitor" view.
4. Wait a couple minutes.
   ⓘ It will likely occur much sooner than that, especially with a board that has native USB capability
5. Try to use the Arduino IDE UI.

🐛 The UI is unresponsive.

Expected behavior

Arduino IDE handles this condition gracefully.

That could even be a limit on the line length that will be displayed, since it is more likely that problematic line lengths would be caused by a missing line break in the sketch than intentionally formatting.

Arduino IDE version

Original report

2.0.0-rc5-snapshot-c9b498f

Last verified with

2.0.0-rc5-snapshot-df8658e (was not fixed by #982)

Operating system

Windows

Operating system version

10

Additional context

There were similar reports of Serial Monitor impact on CPU performance, but those were resolved by #524

• Fast Serial Port reading makes the IDE cpu usage really high and crashes after some time #397
• Serial Monitor lags behind and uses a lot of CPU #519

Additional reports

• Serial Monitor: IDE becomes nearly unusable with really long lines. #2459
• https://forum.arduino.cc/t/2-0-slows-down-if-very-long-lines-but-ok-with-crs-line-feeds-inserted/1021335
• https://forum.arduino.cc/t/ide-2-ver-2-1-wont-close-in-win10/1118105
• https://forum.arduino.cc/t/arduinos-breakdown/1264490

Issue checklist

• I searched for previous reports in the issue tracker
• I verified the problem still occurs when using the latest nightly build
• My report contains all necessary details

[ubidefeo]

@per1234
how does RC7 behave on this?

[per1234]

@ubidefeo still same problem with 2.0.0-rc7