Idle CPU usage on Mac OS X



even running a very simple JUCE program with just a few combo boxes will cause CPU usage when I’m not touching the computer. Depending on the JUCE application it’s between 0.2 and 0.6% on a recent MacBook Pro with 2+2 cores. Other OS X applications stay at 0% when idle.

I’ve used the xcode profiler which identifies MessageManager::runDispatchLoop() as the method that increasingly “wastes” CPU cycles (e.g. 100ms CPU time for a 4-minute test run)

The same JUCE applications on Windows use 0% CPU when idle.

I’m using JUCE 1.52.

Is this anything you’re aware of? Can you reproduce it? (this was originally reported by a concerned customer of mine)



That sounds completely normal. All the apps on my MBP use at least 0.5% cpu when idle, including Apple apps like XCode, etc.

And I’ve changed the way messages are dispatched since 1.52, so there’s not really much point telling me about this unless you’re using the latest version.


Hi Jules,

I appreciate the quick reply! That’s exactly what I hoped to hear – that you’ve recently worked on the message dispatcher, and that for you, the latest dev version doesn’t “behave” differently than other applications.


PS: we just cannot afford to use the development version. Any update of JUCE will cause at least one full “man day” to be spent – re-apply our modifications to JUCE, deprecation/changed API’s, building and TESTING all JUCE based products, sending info and packages to other developers, etc. For reporting bugs, I can use (and have used) the tip, but here it seemed a rather quick thing to check out.