memory-management

问题 I have a C/C++ program that might be hanging when it runs out of memory. We discovered this by running many copies at the same time. I want to debug the program without completely destroying performance on the development machine. Is there a way to limit the memory available so that a new or malloc will return a NULL pointer after, say, 500K of memory has been requested? 回答1: Try turning the question on its head and asking how to limit the amount of memory an OS will allow your process to use

问题 When I read some values from the user and I need to create an array of the specific size I do it somehow like this: #include <iostream> using namespace std; unsigned* numbers; int main() { int a; cin >> a; numbers = new unsigned[a]; } How can I do it with a 2d array(sized a*b read from the user)? 回答1: Anything that would look like a 2D-Array in code will not be a physical 2D array in memory, but either one plain block of memory or scattered, depending on how you allocate it. You can torture

问题 Suppose two ffdf files: library(ff) ff1 <- as.ffdf(data.frame(matrix(rnorm(10*10),ncol=10))) ff2 <- ff1 colnames(ff2) <- 1:10 How can I column bind these without loading them into memory? cbind doesn't work. There is the same question http://stackoverflow.com/questions/18355686/columnbind-ff-data-frames-in-r but it does not have an MWE and the author abandoned it so I reposted. 回答1: You can use the following construct cbind.ffdf2 , making sure the column names of the two input ffdf 's are not

问题 Say, "run myApp.jar with cpu=800 and memory=1024" Ive been doing java programming for many years and it is an embarrasment to ask this question. I don't even know whether this is possible or not. And if so, how? What I just want know is if it is possible to set a java program's maximum memory and cpu usage. I suddenly thought of this because of I recently started developing mobile apps. I want to know how the app will behave on the device which has very limited memory and processor. I saw

问题 Say, "run myApp.jar with cpu=800 and memory=1024" Ive been doing java programming for many years and it is an embarrasment to ask this question. I don't even know whether this is possible or not. And if so, how? What I just want know is if it is possible to set a java program's maximum memory and cpu usage. I suddenly thought of this because of I recently started developing mobile apps. I want to know how the app will behave on the device which has very limited memory and processor. I saw

问题 I've developed my application using my 3G device to test with. Upon giving this to a friend to test, he's noticed that it crashes..I've had a look at the crash log, but it's not much use except for the "EXC_BAD_ACCESS" statement after a few memory warnings. On my device, I can use the imagePicker lots, and each time a photo is taken I get a memory warning, but this doesn't cause any problems. On my friend's device (also a 3G), after a couple of images chosen from the camera, the app crashes.

问题 It may surprise some coders and, as surprising as it can be, it is not possible to implement std::vector without non-standard support of the compilers. The problem essentially resides on the ability to perform pointer arithmetic on a raw storage region. The paper, p0593: Implicit creation of objects for low-level object manipulation, that appears in @ShafikYaghmour answer, exposes clearly the problematic and proposes modification of the standard in order to make implementation of vector like

问题 I noticed that using an NSDateFormatter can be quite costly. I figured out that allocating and initializing the object already consumes a lot of time. Further, it seems that using an NSDateFormatter in multiple threads increases the costs. Can there be a blocking where the threads have to wait for each other? I created a small test application to illustrate the problem. Please check it out. http://github.com/johnjohndoe/TestNSDateFormatter git://github.com/johnjohndoe/TestNSDateFormatter.git

问题 I'm trying to write a size function like this: size(void *p,int size); Which would return the size of an array which is pointed to by p. For example: Int *a = malloc((sizeof(int)*100)); size(a,sizeof(int)); // this should return 100 I think this is possible because if I recall, malloc keeps track of the space allocated in some header bytes. Here's what I have so far: int size(void *p, int size) { p = (unsigned int *)p - 1; unsigned int elements = (*(unsigned int *)p); return elements/size; }

问题 i want do memory management in my project. i do not want operator global new/delete so i implement a simple memory alloctor. this is my code: class IAllocator { public: void* Alloc( unsigned int size ) { 1. alloc memory. 2. trace alloc. } void Dealloc( void* ptr ) { 1. free memory. 2. erase trace info. } template< typename T > void Destructor( T* ptr ) { if ( ptr ) ptr->~T(); } }; // macro for use easy. # define MYNEW( T ) new ( g_Allocator->Alloc( sizeof( T ) ) ) T # define MYDEL( ptr ) if