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Topic: IDE causes high cpu / fan usage (Read 11907 times) previous topic - next topic


Jan 12, 2017, 09:26 pm Last Edit: Jan 12, 2017, 09:27 pm by DaveEvans
Whenever I ran 1.6.5-r5, the cpu usage skyrocketed and the cooling fan ran at high speed.  Adding the Sparkfun FTDI seemed to make things worse.

I recently upgraded to 1.6.12 and have the same behavior.  Red arrows on the screenshot shows when the IDE was closed (FTDI not attached).

Windows 7 Home Premium 64-bit, 2.5 GHz i5 CPU, 6 GB RAM laptop.

Haven't found anything via Google re this problem.

Other than using the on-line IDE, is this fixable?

Coding Badly

Navigate to the Processes tab.  Sort by CPU.

What is first?

What is second?


The first is javaw.exe *32, and the second varies...taskmgr,firefox...

Coding Badly

Odd.  Here the IDE never goes idle but it also never goes above about 2%; usually staying below 1%.

How does Physical Memory Usage look?  About in the middle?


Thanks.  Yup, physical memory is about in the middle.

Coding Badly

Your computer is not much different than mine (Win 7 Pro, 64b, i7 @ 2.2 GHz, 8 GiB, laptop).

In Device Manager, how many serial ports are listed?


Coding Badly

The only ideas I have (all shots in the dark)...

Use Performance Monitor to determine if the CPU is wasting time in the kernel or in the application.  If it is kernel time you may have failing hardware or a buggy kernel driver.


Run the IDE under a debugger to determine what it is doing.


Check the Java version (I don't know how to do that).


Jan 12, 2017, 10:45 pm Last Edit: Jan 12, 2017, 11:03 pm by DaveEvans
Hmmmmmmm... ok, thank you.   Will try to figure out how to do those things.

If you don't mind one more thing... if you go to Control Panel and view by small icons, click on Java, and then General tab -> About..., what do you see?  I have Version 7 Update 9  build 1.7.0_09-b05   


Better than the std process viewer is process explorer from MS HERE

It will show things you would not normally see.

Other reports concerning high CPU usage and Arduinos range from serial modems, bluetooth devices, Antivirus issues, other security software, Actual virus or malware, Other USB devices taking COM resources.
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google (who would have thunk it ! ) or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.


Thank you - I'll try turning off the antivirus, for starters.


Jan 13, 2017, 08:18 am Last Edit: Jan 13, 2017, 08:30 am by DaveEvans
All four processors are pegged at 100% after updating Java to the latest version and turning off anti-virus, so those two items are off the list.

Anything here look unusual?

Coding Badly

Open a command shell.  Run this...



will do when I get home from work...


Jan 14, 2017, 06:39 am Last Edit: Jan 14, 2017, 06:39 am by DaveEvans
JAVA_HOME was not set.  I set it (and updated PATH) to point to the JRE.

CPU usage seems better, but it is still far above your 2%.

I (temporarily) set javaw.exe to run on one core, to be sure I was seeing the IDE, and took the following screenshot.  Usage hits 100% when compiling (horizontal red line).  Before and after, when I'm doing nothing with the IDE, it cycles as shown.  Drops to nothing when the IDE is closed (vertical red line).   Running on all cores...70-50% during compile.

I googled java high cpu usage windows 7 but found nothing definitive.

One good thing has come out of this: cleaning the fan ports helped reduce fan noise...

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