Is an iOS app CPU hovering around 100% normal?

Question

No matter how long I leave the app without touching my cpu doesn't drop below 90% or so. I'm using Parse and I've narrowed it down to Bolts using up the cpu. Is this normal? Is there any way to reduce the usage?

I don't believe I have any endless loops that would cause it.

Look at which thread is using all the CPU. Pause the app and look at the call stack for that thread. This is definitely bad if you aren't doing some obvious, specific processing. — rmaddy, Oct 30 '15 at 16:45
If you don't have an explicit reason for having that linker flag set turn it off, I'd be willing to bet it would fix your problem :) — Albert Renshaw, Oct 30 '15 at 16:48
It looks like it is required by one of the dependencies. I manually deleted it from the list but it still shows up. — Jeremiah, Oct 30 '15 at 16:54
@AlbertRenshaw Can you please explain why you think this (or any) linker flag has any bearing on whether an app is using too much CPU when it runs? — rmaddy, Oct 30 '15 at 17:25
@rmaddy When googling this topic (For Parse --> Bolts) I found many users say that removing that linker flag fixed their high CPU issues — Albert Renshaw, Oct 30 '15 at 18:04
@AlbertRenshaw Interesting but I have that flag in my project and I have no CPU issues. I think removing that flag has a side effect that hides the real issue. — rmaddy, Oct 30 '15 at 18:08
@rmaddy Agreed! I use that flag in most of my projects with fine CPU issues. I assumed it was a Parse Bolts issue with that flag. — Albert Renshaw, Oct 30 '15 at 18:36

Paul Cantrell · Accepted Answer · 2015-10-30T16:55:27.553

3

No, that is not normal, and will drain your users’ batteries. An app that does that is definitely not releasable.

It’s impossible to know how to reduce the usage without much more diagnostic info, but it’s well worth the time to track it down.

A starting point could be to pause the offending thread in the debugger while the CPU is pegged, and see what the code is doing. If it’s inside Parse, as your profile screenshot suggests, that won’t tell you much — but sometimes examining the pegged code in the debugger as it executes reveals info that Instruments does not.

edited Oct 30 '15 at 16:55

answered Oct 30 '15 at 16:27

Paul Cantrell

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Most likely someone is calling Parse much, much, much too often. – gnasher729 Oct 30 '15 at 17:07
Thanks for the advice Paul, I've narrowed it down to a function that when commented out drops the CPU to 0%. I'm still not sure why but it has something to do with pinning objects in Parse. – Jeremiah Oct 30 '15 at 17:20
For anyone who may come across this I fixed it. I was doing a foreach and pinning each object individually. Parse has a function to append an array of objects at once. Seems like a bug in Parse. – Jeremiah Oct 30 '15 at 17:31

Is an iOS app CPU hovering around 100% normal?

1 Answers1