I have a quite a big iPad app and when I run the app in xcode debug mode, it shows about 50 MB in the Activity Monitor and memory grows slowly. (About 0.1 MB per 30 seconds approximately.) But when I run the app directly from the simulator(which is already installed in the simulator) , it shows about 10 MB in the activity monitor and memory is not growing.(its constant). I have checked the performance though the instruments and no leaks showing there.
Does anyone know for reason to showing different memory details for above 2 scenarios and which one is correct?
Also is there a way to programatically print the consumed memory by the app in the console?
Activity Monitor is a generally useless way to track memory growth. There are about a zillion different contributors to RPRVT, some of which are entirely non-intuitive. Activity Monitor can certainly be used to figure out "uh, oh, it is growing", but not much beyond that.
Use Instruments to track memory growth.
When you say "run in Debug mode", do you have anything configured like zombie tracking or allocation information tracking? That'll contribute to memory growth.
Beyond that, the Allocation Instrument will generally show you what is contributing to growth.
Also is there a way to programatically print the consumed memory by the app in the console?
An absolute number like this isn't very useful. That an app is growing is bad, but a raw number won't tell you why any more usefully than Activity Monitor.
Use Instruments. :)
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I am developing an Application for iPad & it consumes 5.5 MB at max on RAM of the iPad. I have ensured all this stuff using Instruments number of times. As soon as App uses little bit more memory, It throws memory warnings & app start behaving abnormally.
I have implemented the lines of code for freeing the memory in did-receive memory warning.
I also have ensured that NO LEAKS in the entire app.
I came to know that App needs at-least 6 mb memory.
Here is the general flow of the app.
log in -> 1st-list View -> 2nd-list view -> 3rd-list view -> 4th-Map & listview -> 5.Map&List
brief of each screen.
log-in - simple screen with username-pswd, making a web-service call & authenticating user
based on result of authentication, it will fetch few more data & list it on 1st-list View screen.
based on selection from 1st-list, app will load list on 2nd-list view
based on selection from 2nd-list, app will load list on 3rd-list view
based on selection from 3rd-list, app will load list & map will have pins relatively.
based on annotation from Map, app will navigate to another maps & different pins.
Here, app receives memory warnings on 6th screen. I have ensured all coding standards & all importance of all objects.
In Above case, All screens are very necessary, I am using Navigation Controller & just pushing view-controllers one by one. no duplications - ensured twice.
Now, the point is, App is being tested on iPad-1 with iOS 4.1 & all apps are forcefully closed before starting the testing of the app.
THOUGH, app receives warnings # just 5.5 mb usage.
I tried to convince my project managers that, this amount of memory usage is high & they are asking me - there should some option to set MEMORY. How this kind of High Graphics games & apps are running smoothly ?
I can't find appropriate document from Apple saying LIMIT. I have no answer to them.
If setting Memory limit is not possible, I am requesting you to provide Appropriate PROOF link, so that I can show it to my Project Manager.
If that kind of settings is possible, I am highly eager to know how to make that.
I doubt you will find any positive statement about memory limits for an app under iOS coming from Apple docs.
But if you google "ios app available memory" you will find a lot of information; e.g., this S.O. thread.
In my experience, my apps can sustain a "peak" memory usage of about 20MB (depending on the device state), but then memory use must quickly go well below the 10MB threshold for the app not to be killed (I would say that 6-8MB is more precise figure). Sometimes an app can be killed just because a peak cannot be "undone" fast enough.
One piece of information that might be useful for your managers is the output from the "Memory Monitor" tool in Instruments, specifically the "free physical memory". If you use it, you will invariably see that your app will be killed when the "free physical memory" goes below a given limit (as per Instruments output), approaching zero left memory.
Now, whether that limit is reached because you allocated some memory (which is reported by the Allocations or Leaks tools) or because of other factors (a framework loaded into memory? something in the iOS kernel or that is not tracked by Instruments?) you cannot know. But for sure you can follow how the free physical memory in the device varies over time with the use of your app.
Hope this helps.
The first generation iPad has a total of 256 MB of memory. Of course some of that will be used by the operating system itself.
It's very conservative to assume that at least 64 MB would be available for your application. So 6 MB sounds pretty minimal to me. There must be something your application is doing that causes more memory to be allocated.
There definitely isn't some "I'm a game let me use more memory option". All applications are allowed to use as much memory as they can (though it's always a good practice to minimize memory usage). If memory runs low, the application is notified, and if memory is exhausted, the foreground application is terminated.
If your application is terminated, examine the crash log to see how much memory it was using. My guess is that you'll find you are using more than you think.
This question is NOT about retain/release things in iphone memory management. I understand the routine quite well and there is no memory leak things in my app.
I pop up the question shown in the title, when I use Activity Instruments to monitor the overall memory activity of my app.
The instrument always shows that the amount of "real memory", which my app is using, keeps being between 21 MB and 30MB, never higher. I think this amount is relatively not big. However, sometimes, my app will give level 1 or 2 memory warning (never crash and I don't do anything for this warning in my code).
so I am wondering what's really behind iphone memory thing. I mean, does real memory the only things that triggers warnings? or there is anything else (such as virtual memory, as shown in the Instruments) inside the whole memory I should take care of?
Although my app never crash due to memory issues, this warning thing (especially level 2 warning) really annoys me and makes me fear of crashing once I release it to public in the future.
Any help?
Thanks
Memory warnings exist to tell your app you're nearing your limit. They are not necessarily a 'bad' thing - plenty of applications simply ignore them.
The actual implementation details about when a memory warning is triggered are not important, and in fact will vary considerably from device to device. An iPhone 4 might have 512MB of RAM to play with, but a 3GS will have half that.
That said, there are some things worth knowing about memory warnings:
A memory warning is triggered when the overall amount of available free memory reaches a certain level
These levels are undocumented. So you don't know what the difference is between a level 1 warning and a level 2 warning, other than the fact 2 is worse (more urgent) than 1
Memory warnings are not application specific. A memory warning is delivered to all applications currently running and not suspended. So you may not be directly responsible for triggering one.
When memory warnings are received the system will try and free up memory on your behalf
Again, the exact implementation details are undocumented, and you shouldn't need to care about them. A memory warning is an opportunity for you to help the system by freeing up any objects you don't need.
I have an iOS 3.2 program running on the iPad that is document-centric. Sometimes, when closing a document, there is a memory spike in Instruments. I'm pretty sure I'm not leaking memory, since the allocations graph stays pretty steady between 5mb and 10mb, except when closing, where it spikes up by about 5mb or so (and the leaks tool is showing very small leaks, a few k total, nothing that I'd expect to cause crashing).
This seems to be leading to iOS getting fed up and jettisoning my app. The memory use never goes about about 12mb, but the error log report displays that it's using 19988 "Count resident pages", which is way, way higher than anything else.
My problem is that I have no idea where the spikes are happening or why. It's the same code, over and over, and sometimes a document will spike, other times it won't. There doesn't seem to be a way to use both the debugger to step through the code and Instruments to see what's going on at the same time, so I'm not sure how to track down this problem.
Is there a way to see the memory use in the debugger?
IIRC, Instruments should have an Allocations tool which would show you what is demanding all that memory. If you open up the right side bar, there'll be extra information which shows the code path it used for that allocation.
I'm reading some people stating that if another (3rd party) app on someone's iPhone has been leaking memory, that this may reduce the (mystery) amount of RAM your app would otherwise have available.
This confuses me -- does not all app memory get released when the app is closed by the user? And only one app is open at a time on iPhone?
Normally, any memory that your application allocates will be freed when it exits. However, many of Apple's applications continue running after they're "closed", so memory leaks in Mail, for instance, can affect available memory.
In addition, there are apps out there that claim to free up allocated memory. They really don't do anything other than force some dirty pages out of the buffer cache, but they appear to do something, so people believe they must be doing something useful.
On a jailbroken phone - yes, third party apps can be running at the same time as yours. Running out of memory is common with people who like to have many apps running at once hence the need for task managers, killing tasks etc.
On an unhacked phone - no. Yours is the only non-apple app that is running, no others can run at the same time.
So what can you do? All you can do is try to use the minimum memory possible which you're probably already doing. Realistically you can only test with a factory, unhacked phone, unless you are going to spend hours trying to please everyone. If you think you are maybe using too much you could identify the larger allocations using the instruments tools ("Run with performance tool >" from within Xcode) and then post that chunk of code here to get ideas of how to reduce it.
You should run Instruments and then add the instrument "Memory Monitor" to see the memory use of all of the other processes on your phone. (Add with Window -> Library , then drag the Memory Monitor instrument to the instrument panel.
What I'm still trying to determine is why is iOS releasing memory from MY app, and not all of the other memory pig apps that are not currently running.
I know this is a subjective question. As far as I know, there are somewhat about 25 MB available for the app, but it depends on what else is going on. Currently playing music, a current phone call or what ever might drop that amount of memory down a lot. I don't know.
Just tell us what you think, or what you have experienced. My app currently consumes about 15 MB at a time, mostly lots of images loaded into views for animation. I have encountered no problems with this. But is there some "border" that can be drawn, to make a simple-to-follow rule like "do not consume more than x MB of memory at any given time", where x stands for the max amount?
This value highly varies per device and per user. For example, I restart my phone every few days, freeing up lost memory claimed by Apple and 3rd party leaks. My mother, has not restarted her phone ever on her own. EVER. She has tons of trouble with apps, gives me a call and I tell her to restart the phone to increase the ram. She does and the apps dont crash anymore.
Moral of the story is: Never plan on having available memory. You should always keep your memory down to the bare minimum you need at any given time.
You can use Instruments and launch some apps and find out for yourself.
Recently I found this awesome tool to find what is the maximum memory capacity of any iOS device.
We can also find at which memory level we received the Low Memory warning.
here is the link: https://github.com/Split82/iOSMemoryBudgetTest