I am trying to see how much memory my program uses and identify leaks. I have tried looking at the memory page built into xcode and also the Allocation instrument. They get totally different result though (Both simulated on my 6s).
An outline of what I did...
I have a tableview that loads images from firebase. My test was keep pressing "reload all data" button at 3 second interval for a bit (30 seconds) and observe how the memory reflects what I did. Below are the results of the two screen shots.
What is weird is that for xcode result, I see that my memory just continues to climb higher and higher upon every refresh (Which suggests that I have a leak somewhere as the table view should discard the original data and load new ones. So I would expect highs and lows). So I went into the allocation instrument and did the same test. However, what I instead see is that the total persistent byte doesnt grow as crazy as before and remains hovering around 23.36mb with minor highs and lows (As what I might expect for reloading a table?)
Any explanations?
-- Update--
The answer here appears to contradict to what I believe is right
Xcode Memory Graph - showing increasing memory use - what exactly does it show?
Because I have tried hitting the refresh button for an hour to let the memory build up to nearly 1.5GB and I did get a memory warning. So I dont believe Xcode is showing "total bytes".
Related
In my iOS app I am running the instruments tool to see the memory allocated. In the app I call CoreData and use that to create a survey using Apple's ResearchKit. Every time I run a new one I see an increase in the amount of 'persistant bytes' increases. When the app is run, whenever it is run multiple time over and over eventually the app closes.
I can see using Fabric's Crashylitics that a Out of Memory session occurred.
What's the best way to go about finding and fixing the memory that seems to be retained?
Your screenshot is not showing any memory leaks so you should start by using the Allocations instrument, the graph of which is in your screenshot.
Start by setting an inspection range where the memory usage spikes. Click in the graph and drag to set the inspection range. You will notice that the graph color outside the inspection range changes to gray. At this point you have focus on where the memory usage spikes.
To find the place in your code that's causing the increase in memory usage, switch to the call tree view by clicking in the jump bar below the graph and choosing Call Trees. Inverting the call tree and hiding system libraries makes it much easier to find your code in the call tree. Click the Call Tree button at the bottom of the window to invert the call tree and hide system libraries.
If you find a function in the call tree that is allocating a lot of memory, you can double-click it to show the lines of code that are allocating the memory.
Another tool you can use to analyze memory growth is the Allocations instrument's generations. Run your app, pause, and click the Mark Generation button to create a generation. Repeat to create multiple generations. Choose Generations from the jump bar to see how much memory growth you have from generation to generation.
I'm having a memory issue with one specific ViewController and memory. When I launch my app in debug mode, it launches with 40mb memory usage. (I have no idea if this is already a lot or not -- what is common?). Then, when I open this specific view, it spikes up to about 120mb. The issue is, when I pop this view (with the navigationController popViewController), the memory stays up at 120mb. And then, when I re-open it, it spikes to 200mb (a 80mb increase every time).
With other similar ViewController it spikes up to 120mb too, but when I close the view, it goes back down to more or less 40mb.
The problem is that this specific view contains quite a bit of code (about 1000 lines...) and it's impossible for me to post everything here.
What methods should I use to specifically locate the issue in xCode?
For anyone I might be able to help with this:
use the tools in xCode as recommended. There are some great tutorials online.
In my case it was an issue with an [NSTimer] which kept a strong reference to my view, so it never got released afterwards, thus stacking up memory. Make sure to stop your time when you pop a view.
Long story here, so bear with me...
I have a view controller which, when presented more than three times throughout the life of an application session, will hang and lock and freeze my entire application. Even the Springboard locks up until my app's fully backgrounded! In Xcode's inspector, I noticed rather alarmingly that the memory footprint would jump a good 5-8 MB every time I presented that view, and it wouldn't go down again after dismissal. By the time the fourth invocation rolls around, the app's already using 40 MB of memory.
My first thought was, "OMG, itz a memry leek!" The second one told me to hop into Instruments and track it down.
While the Leaks tool did help some, it only told me that the app was leaking like crazy. All it would tell me was that, somewhere in these four second intervals, I had gained between "4 new leaks" and "17 new leaks." They did correspond to my opening that view, though, and once I started commenting random stuff (and following the sometimes helpful guidance of the Allocations tool), I tracked most of them down to three extra lines of code. "Oh well, I don't need those views anyway!" Those three lines no longer exist, and Instruments no longer complains.
My only complaint here is that my UI still behaves the same! On the fourth presentation, the entire app slows down. Upon further inspection of Xcode's instruments, I see that not only is the memory still going up (only to 30 rather than 40 MB this time), but the CPU activity has tanked!
Ok, granted I should have looked there in the first place, but I ain't perfect!
I ran the app again, and found that the overall CPU activity rose consistently the more I presented that view controller. By the third one, it was up to 40-60%. The main thread seemed pretty clear, and most of the activity was spread between eight other background threads (who knows what all those do).
The fourth time I opened that view, I had expected everything to block like crazy. It didn't. The CPU just... stopped. It was running at around 50-ish% when, by the time my finger had left the screen, it was down at 1%. All of the thread graphs shrunk from spiked stalagmites to tiny waves in a puddle. According to the pie chart, the vast majority of the processor was free to do as it liked. It doesn't like me.
I literally have no clue why it does this. I've been stuck in a room for days now trying to figure this out. Any help or advice would be much appreciated.
Does anyone have any idea why this happens, how this happens, or what I can do to make this not happen?? I'm drawing a blank here...
Thank you so much!
It should be noted that I got these by running the app on my iPhone 5s. Yes, I did try on the simulator, but my little MacBook Air took it like a champ, and was no help in figuring this out, except to tell me that the problem happened on iPhones.
I've run into this before, and the following is my general approach that usually allows me to fix these types of memory leaks.
First I would put a print statement into you viewController to see if your VC is being deallocated when it is being popped.
deinit {
print(self.description)
}
The next step, in the case that the ViewController is not being deallocated, I would start by removing core pieces, bottom up, commenting them out chunks one step at a time, yet leaving the back control that hides the view controller visible. Usually you can isolate the memory leak once you see the deInit get called after removing some code, you may have hit the part that made a strong cycle reference.
One more thing, ensure that all your delegates are declared weak, and search through your code for closures, and check that the closures aren't holding hard references within, especially to self.
Also, checkout this article to see the about using unowned or weak, when passing in instances into a closure, could be helpful.
http://krakendev.io/blog/weak-and-unowned-references-in-swift
When will i have running my app in simulator. xCode debug section shows cpu and memory section it will display some graph flow. but i don't know what is that.
My question is,
what is that cpu and memory graph
when i running my app the memory increase towards when ever i navigate to any other viewcontroller and return back same or other viewcontroller etc., it always increase the memory size.
why it occurs. Is that any problem. if yes how to fix that and why i caused.
Here below image i navigated to any other view controller. it is suddenly increase from above image memory size to below image memory size.
Well from overall memory consumption it would seem as if you are handling some images or videos or other heavy content. Many make memory leaks handling those. To test if thats a real leak, you can do so:
Go to some page A (any page), from there go to some other page B, then back to A, back to B.. repeat that and if your memory is really getting high - you have a leak.
BUT bear in mind: These graphs show you how much resources your app use from your device, you SHOULD NOT use that to find leaks. Instead go to profiler, choose memory leaks and use that. If you are using ARC and cannot find any leaks, you can use "mark heap" button in allocations instrument to find memory build ups like this: Repeat the "page A page B" cycle and every time you are in page A, press "mark heap" button. You will now see generations which each show how much memory has increased from last generation. If it always keeps increasing same amount - double clicking generation will show you all the places that you have possible leaks.
Additional info: Easiest way to profile your app is to hold left mouse on "play" button in xcode until more buttons pop-up. Choose profile. When instruments appear - choose "Leaks".
From there - you should be able to see overall statistics of your app. I will not go in detail about profiler, because all the info is already available in the net. For example: https://developer.apple.com/library/mac/documentation/DeveloperTools/Conceptual/InstrumentsUserGuide/Introduction/Introduction.html
I'm doing a screenshot of the allocations in my project. I've simulated a memory warning at 50 seconds, but the allocations never go back down. Maybe I don't understand this one correctly?
I think the graph is displaying the overall bytes, ie all the memory consumed by the application during her running time
It turns out that NONE of my big objects (UIViews / Controllers) were ever being released. After diving in I'm seeing some up and down like I should be.