memory-management

问题 I'm using matplotlib to generate many plots of the results of a numerical simulation. The plots are used as frames in a video, and so I'm generating many of them by repeatedly calling a function similar to this one: from pylab import * def plot_density(filename,i,t,psi_Na): figure(figsize=(8,6)) imshow(abs(psi_Na)**2,origin = 'lower') savefig(filename + '_%04d.png'%i) clf() The problem is that the memory usage of the python process grows by a couple of megabytes with every call to this

问题 I am trying to get a handle on proper memory usage and garbage collection in Java. I'm not a novice programmer by any means, but it always seems to me that once Java touches some memory, it will never be released for other applications to use. In that case, you have to make sure your peak memory is never too high, or your application will continually use whatever the peak memory usage was. I wrote a small sample program trying to demonstrate this. It basically has 4 buttons... Fill class

问题 I am a student and pretty new to programming. I am trying to learn Objective-C/Swift in my spare time. I made a game using spriteKit with swift that has multiple menus/scenes. I am trying to transition from one view controller to another. To do this I used this code: @IBAction func PlayButtonPressed(sender: AnyObject) { let playStoryboard : UIStoryboard = UIStoryboard(name: "Main", bundle: nil) let vc : UIViewController = playStoryboard.instantiateViewControllerWithIdentifier("playGame") as

问题 so in c++ it's very easy. you want whatever class/struct to be allocated on the heap, use new. if you want it on the stack, don't use new. in C# we always use the new keyword, and depending on whether it's a struct or a class it's allocated either on the stack or on the heap (structs go to the stack, classes to the heap) - and in some applications there can be a HUGE performance difference when changing the design such that only those objects go to the heap that really belong there. What I

问题 so in c++ it's very easy. you want whatever class/struct to be allocated on the heap, use new. if you want it on the stack, don't use new. in C# we always use the new keyword, and depending on whether it's a struct or a class it's allocated either on the stack or on the heap (structs go to the stack, classes to the heap) - and in some applications there can be a HUGE performance difference when changing the design such that only those objects go to the heap that really belong there. What I

问题 Before ARC I had the following code that retains the delegate while an async operation is in progress: - (void)startAsyncWork { [_delegate retain]; // calls executeAsyncWork asynchronously } - (void)executeAsyncWork { // when finished, calls stopAsyncWork } - (void)stopAsyncWork { [_delegate release]; } What is the equivalent to this pattern with ARC? 回答1: Why not just assign your delegate object to a strong ivar for the duration of the asynchronous task? Or have a local variable in

问题 I've read a few articles, and I understood the following (please correct me and/or edit the question if I'm wrong): The java heap is segmented like this: Young Generation: objects that are created go here, this part is frequently and inexpensively garbage collected Old Generation: objects that survive the garbage collections of the Young generation go here, this area is garbage collected less frequently and using a more CPU demanding process/algorithm (I believe it's called mark-sweep) Edit:

问题 I have some places where implementing some sort of cache might be useful. For example in cases of doing resource lookups based on custom strings, finding names of properties using reflection, or to have only one PropertyChangedEventArgs per property name. A simple example of the last one: public static class Cache { private static Dictionary<string, PropertyChangedEventArgs> cache; static Cache() { cache = new Dictionary<string, PropertyChangedEventArgs>(); } public static

问题 Is it safe in Objective-C to write self.propery = [[SomeClass alloc] init]; instead of SomeClass *tmp = [[SomeClass alloc] init]; self.property = tmp; [tmp release]; or will the first form leak memory? 回答1: The first example leaks unless you provide a custom property setter. You can use: self.propery = [[[SomeClass alloc] init] autorelease]; Instead. 回答2: It depends on how the property is defined. If it's defined with retain or copy then, yes, your first example will leak. 回答3: The first one

问题 We have a page that contains 77 or so video thumbnails. When a video thumbnail is hovered over, video starts playing within the thumbnail space. A problem occurs after many (8 to 60 depending on the system/browser) of them get hovered over. The video starts playing incorrectly, or not playing. Basically the flat/redundant areas turn all dark. In Edge, this corrects itself after a second or two, but for our client this is very undesirable behavior. We made an improvement by pausing each video