I would like to make an mobile application, what contains a lot of picture
My question how can I dynamically open the picture and delete from memory?
I tested this:
a = Texture.new("a.jpg")
print(Application:getTextureMemoryUsage()) -- write x
a = nil
print(Application:getTextureMemoryUsage()) -- write x again
Thanks for help.
Problem is that garbage is not collected right away and that is why memory is not freed right away.
You could try calling collectgarbage() couple of times to force it as:
print(math.floor(collectgarbage("count")))
collectgarbage()
collectgarbage()
collectgarbage()
print(math.floor(collectgarbage("count")))
Related
I am writing android renderscript code which requires back to back kernel calls (sometimes output of one kernel become input of other). I also have some global pointers, binded to memory from Java layer. Each kernel updates those global pointers and outputs something. I hav e to make sure that execute of kernel1 is finished, before kernel2 starts execution.
I looked at android renderscript docs, but couldn't understand syncAll(Usage) and finish() well. Can anyone clarify how to achieve this behaviour?
Thanks
mScript.forEach_kernel1(mColorImageAllocation, tempAlloc);
// make sure kernel1 finishes, from android rs doc, copyTo should block
tempAlloc.copyTo(testOutputBitmap);
for (short i = 0; i < NUM_DIST; i++) {
mScript.set_gCurrentDistanceIndex(i);
mScript.forEach_kernel2(tempAlloc);
mRS.finish(); // wait till kernel2 finishes
}
In the above example, same kernel2 is called with different global parameters on kernel1's output.
For this code you don't need either. RS is a pipeline model so any work which could impact the result of a later command must be finished first by the driver.
syncAll() is used to sync memory spaces not execution. For example to propagate changes from script memory to graphics memory.
The phenomenon: First do allocation some big memory blocks in the Java side until we catche OutOfMemoryError, then free them all. Now, weird things happen: load even a small picture(e.g. width:200, height:200) by BitmapFactory.decodeXXX(decodeResource, decodeFile, ...) will throw an OutOfMemoryError! But its OK to alloc any pure Java big Object(e.g. new byte[2*1024*1024]) now!
Verifying: I wrote some simple codes to verify the problem that can download here, press "Alloc" button many times and you will got an OOF Error, then press "Free All", now the environment is set up. Now you can press "LoadBitmap" and you will see its not work on most of Android 2.x phone.(But in the emulator its just OK, odd)
Digging deeper: I try to dig into some dalvik code to find out why, and find a possible bug in function externalAllocPossible in HeapSource.c which called by dvmTrackExternalAllocation who print the "xxx-byte external allocation too large for this process" messages in LogCat.
In externalAllocPossible it simply wrote:
if (currentHeapSize + hs->externalBytesAllocated + n <=
heap->absoluteMaxSize)
{
return true;
}
return false;
Which means once if the native Bitmap allocation size plus the currentHeapSize(NOT the actually allocated size as shown below, in this case, it's keeping the max size of the heap we bumped up but then freed them all) exceeds the limits, native Bitmap allocation will always fail, but the currentHeapSize in Java seems NOT decrease even when 91.3% Java objects' memory have been freed(set to null and trigger GC)!
Is there anybody else met this problem too?
I think this is correct. Its forcing the entire app (Java+native) take no more than a certain amount of memory from the OS. To do this it has to use the current heap size, because that amount of memory is still allocated to the app (it is not returned to the OS when freed by GC, only returned to the application's memory pool).
At any rate, 2.x is long dead so they're not going to fix it there. They did change how bitmaps store their memory in 3.x and 4.x. Your best bet is to allocate all the bitmaps you use first, then allocate those large structures. Or better yet- throw those large structures into a fixed size LRUCache, and don't use the grow until out of memory idea, instead load new data only when needed.
The class Bitmap has the recycle() method, described as:
Free the native object associated with this bitmap...
The reason behind this method is that there are two heaps: the Java heap and the heap used by native code. The GC only sees the Java heap sizes; for GC, a bitmap may look as a small object because it's size on the Java heap is small, despite the fact that it references a large memory block in the native heap.
I had a user comment that after viewing a bunch of images in my app, it crashes (he believes that it is due to out of memory error). I have the following relevant code:
int themeID = mNav[mPos];
String icon = getThemeData(DbAdapter.KEY_ICON, themeID);
ImageView viewer = (ImageView)findViewById(R.id.viewer);
Bitmap bMap = null;
try {
bMap = getJPG(icon + ".jpg");
} catch (IOException e) {
e.printStackTrace();
}
viewer.setImageBitmap(bMap);
That gets reran as the user flips between images. From here I see that you should call recycle() on bitmaps. Do i need to call it on bMap after setting the image? Or is there some way to pull it from viwer prior to setting the next one?
According to the documentation for recycle (if I call it on bMap) it appears I don't need to use it: This is an advanced call, and normally need not be called, since the normal GC process will free up this memory when there are no more references to this bitmap.
If you need to explicitly call recycle() it probably means that you have memory leak. Calling it is almost never a solution.
Did you try to check your app for potential mmory leak?
To check it you can for example rotate your device a few times and check how the Garbage Collector behaves. You should have something like GC_... freed 211K, 71% free 300K/1024K, external 0K/0K, paused 1ms+1ms in your LogCat nearly every time you rotate. Watch for changes in this part: 300K/1024K. If you don't have memory leaks, the first part should grow and then get smaller after a few GCs. If you have a memory leak, it will grow and grow, to the point of OOM error.
Check out my other answer about a memory leak.
If you're sure you don't have a leak and you're operating on Honeycomb you can increase the heap size accessible for your app like this: android:largeHeap="true" but it's only recommended when you deal with some huuuge bitmaps or videos, so don't overuse it.
i have an Android app that displays alot of images, it works, the images are gatherd from an url, added to a que and gathered by 4 threads,stored in a cache and then displayed in a listview view 4 images for row, there are abot six rows at each time on the screen. There is a total of usually 90 images.
The rows(and imageviews) are always recycled, so the amount of items is always the same and i'm not initializing anything.
This seems to work quite fine, i have always an average used heap size of 13MB.
The problem i have is that at the beginning mi max heap size is quite small and i get GC messages like:
01-20 16:48:39.191: D/dalvikvm(9743): GC_FOR_ALLOC freed <1K, 31% free 12048K/17351K, paused 25ms
but the more i scroll up down the view the heap size grows more and more untile i get things like
01-20 17:02:05.339: D/dalvikvm(11730): GC_FOR_ALLOC freed 544K, 72% free 13871K/49159K, paused 35ms
as you see even if the used is the same the maximum is increased even if i never got to that limit. and the true problem is that at this point i start to get outofmemory errors.
Can someone explain me what's wrong?
Thanks!
What version of Android are you using? If you're testing on pre 3.0 (ie 2.x), the byte arrays that store most of the information in Bitmaps are allocated and stored in native memory. This means that in heap dumps and in the GC notifications, you only see the small amount of memory used for pointers in Bitmaps, rather than the actual size.
For more information check out this google IO talk on memory management and detecting memory leaks: http://www.youtube.com/watch?v=_CruQY55HOk
Also I've worked on several apps doing similar things. My guess is that either your cache size is way too large, or (more likely) the images you're displaying and storing in the cache are much larger than the size you actually want. If you display a bitmap in an image view, the imageview will store the original bitmap in memory, even if it is significantly larger than what would actually fit in the view. Try resizing the images from disk to at least closer to the appropriate size before trying to display them: How do I scale a streaming bitmap in-place without reading the whole image first?
To cache my Images I use Map<String, Drawable> drawableMap. On a OutOfMemoryError I call this function:
private void cacheLeeren()
{
int size = drawableMap.size();
int del = (int) (size * 0.3);
Set<String> s = drawableMap.keySet();
for (String t : s)
{
if (del >= 0)
{
drawableMap.put(t, null);
del--;
}
}
}
I think it's not the best way...but it works ;-)
My guess is that your app reaches a very high peak of memory usage for a short time. It's true that on average you only use 13MB but if your heap grows to as much as 50MB, it means that momentarily you've consumed much more memory than you're thinking.
Let's try to figure out where this is happening. You've mentioned that you're using an LRU cache. This cache frees memory as soon as it fills up. My guess is that you're starting to free memory too late, and this memory isn't freed immediately - since it depends on the system GC. Whenever you're freeing some items from the cache, try to call System.gc() manually.
You've also mentioned that you're calling Bitmap.recycle(). To the best of my knowledge this is useless on Android 3+ because the native heap is no longer used for bitmaps. Since all bitmaps are on the dalvik heap, they will be freed by the GC.. You can't rush this like before unless you call System.GC() yourself.
Another idea for your source of problems is heap fragmentation. See my previous SO answer to a similar issue in this question.
Well, I'm working on an app that loads images from Internet. Everything is OK so far, but I'd like to know how could I calculate how long such images take to be loaded from Internet?
There is any method on Bitmap to make that? Maybe there is any other way that you would suggest me?
Cheers,
Well if you know the filesize b of the image (in bytes), and the speed s at which it's downloading (in bytes per second), then the time t (in seconds) to download the file will be:
t = b / s
Simple math really to convert your units as needed. Don't forget that this value is constantly changing as the download speed changes.
Edit: Now if you're only looking to calculate how long the image took to download and maybe display this information after the fact, then a simple solution would be to start a timer when the download is initiated and stop it when it's done.
HTTP response will contain a Content-Length field this will let you know how much is to be downloaded. If you know the speed of your conection then you can work out the estimated time using time = dataSize / downloadSpeed.
You can also use the knowlege of how much you have downloaded so far to work out how long it will take using linear extrapolation. time = (dataSize * (timeNow - timeStart)) / dataDownloadedNow