High CPU load - Bug of code editor?

[PascalKoe]

When I have Arduino running in the background (doesn't matter if device is connected or not) the IDE has a ~33% load on my CPU.
If I loose the focus of the code editor within the IDE by for example opening the serial monitor, clicking the little down arrow to create a new tab or using the upper menu, the load on the CPU drops to ~0%. After closing the serial monitor (or closing the menus, ...) and typing in the code editor the CPU load stays low. Everything fine like that.
But now if I loose focus of the IDE Window and regain focus on the window, the CPU load rises back up again to ~33% load.

Arduino IDE Version 1.8.7
Windows 10 Pro 64bit Version 10.0.17134 Build 17134
Intel Core i5-4570
8GB DDR3 RAM

Only thing special about my system is that I'm using WinToUsb (Bootloader installed on an external M.2 drive, Windows is on a VHD on the external drive which gets mounted and started from).

Does this bug exist on other systems?

Thank you

[facchinm]

Hi @PascalKoe ,
there's some similar report (#7505) but nothing so reproducible 😳
Could you test 1.8.6 down to 1.8.4 (using the zip non admin "installation") and report if the same problem occurs?
My guess is that an action called by some focusLost() is getting stuck in an infinite loop.
If you were on IDE 1.9.0 beta it would almost certainly be caused by the file watcher, but on 1.8.7 I don't have a clue.

[PascalKoe]

Hi @facchinm
Tester Versions 1.8.7 to 1.8.4 and 1.9.0-beta-81.
Version 1.8.6 and higher (including the 1.9.0 beta) have the same issue.

Other modifications I made to the IDE are...
... changing the font to Consolas but changing back to Monospaced doesn't make a difference
... installed the ESP32 Core using the boardmanager
... installed VisualMicro

Additionally I do not have Java installed on my machine.
Maybe I will try to install Java and see if that makes a difference.

[PascalKoe]

Just build the IDE myself like described on the wiki page. Works without the bug :)
The hourly build (17 September 2018 10:43:2 GMT) still has the bug.. Shouldn't the hourly and the self build be identically?
I was able to recreate the bug on a different installation by booting a Windows 10 Edge developer vhdx, available here (MSEdge on Windows 10, HyperV).

[facchinm]

@PascalKoe I've been able to reproduce the problem and it looks related with JRE u171 . Moving to u181 seems to fix the high CPU load while in background issue. I'm updating the bundled jre in hourly, it would be nice if you could try it in some hours to make sure the bug has gone.

[pierre83]

Hello,
Please note that I have the same problem with my Windows Vista but not on my Windows 10 PC.
The JAVA process is using 50% of my old CPU.(JAVA_VERSION="1.8.0_171")
Trying your new bundle but this is the same package...(JAVA_VERSION="1.8.0_171")
Pierre

[facchinm]

Hi @pierre83 ,
the hourly version available here (https://www.arduino.cc/download.php?f=/arduino-nightly-windows.zip) contains JREu181 ; would you mind testing it? Thanks!

[PascalKoe]

Sorry for the delay.
Yes, the bug seems fixed in the current nightly :)
Thank you!
Pascal

[pierre83]

Hi !
Thank you all, yesterday, I downloaded the nightly (with JREu181) and the problem is gone !

Pierre

[sergbrest]

I also confirm the problem is gone ! Ver. nightly 2018/09/20 02:27

[pierre83]

Hello,
The CPU problem is gone but I encountered a new problem, which is not related to the JAVA version.
It's impossible to load thru "ArduinoAsISP" on a barebone ATMEGA328P, because the "
arduinoasisp.protocol=stk500v1" and "arduinoasisp.program.protocol=stk500v1" lines in the programmers.txt file are not to "stk500v1" like here but with "arduino"

[facchinm]

@pierre83 this is another problem, please open another issue to properly keep track of it, thanks.