10 int structs would be allocated on the the heap, only pointer to them would be on stack, correct? Yes, correct. How would one make fixed size array to go on stack? What if I’m using stucts I defined? The stackalloc keyword serves this purpose. However, this works in unsafe context only, which is a … Read more
I’ve used tcmalloc and read about Hoard. Both have similar implementations and both achieve roughly linear performance scaling with respect to the number of threads/CPUs (according to the graphs on their respective sites). So: if performance is really that incredibly crucial, then do performance/load testing. Otherwise, just roll a dice and pick one of the … Read more
With this version of java -XX:+DoEscapeAnalysis results in far less gc activity and 14x faster execution. $ java -version java version “1.6.0_14” Java(TM) SE Runtime Environment (build 1.6.0_14-b08) Java HotSpot(TM) Client VM (build 14.0-b16, mixed mode, sharing) $ uname -a Linux xxx 2.6.18-4-686 #1 SMP Mon Mar 26 17:17:36 UTC 2007 i686 GNU/Linux Without escape … Read more
Efficiency should not be your concern. Write clean maintainable code. It bothers me that so many answers indicate that the memcpy() is inefficient. It is designed to be the most efficient way of copy blocks of memory (for C programs). So I wrote the following as a test: #include <algorithm> extern float a[3]; extern float … Read more
The Memory Model The C++ standard has a memory model. It attempts to model the memory in a computer system in a generic way. The standard defines that a byte is a storage unit in the memory model and that memory is made up of bytes (ยง1.7): The fundamental storage unit in the C++ memory … Read more
Your array is way too big to fit into the stack, consider using the heap: int *sieve = malloc(2000000 * sizeof(*sieve)); If you really want to change the stack size, take a look at this document. Tip: – Don’t forget to free your dynamically allocated memory when it’s no-longer needed.
To answer the whys, profiling memory usage is especially important for iOS apps because iPhones and iPads have much less RAM than Macs. The iPhone 4 has 512 MB of RAM, but earlier versions had 256 or 128 MB. Factor in the RAM the OS uses and multitasking, and your app doesn’t have much RAM … Read more
First, read this post from Eric Lippert on The Stack is an Implementation Detail. Follow it with The Truth about Value Types. As for your specific question Are struct instances sometimes allocated on the heap? Yes, they are sometimes allocated on the heap. There are lots of examples of when they could be allocated on … Read more
Alloc: Class method of NSObject. Returns a new instance of the receiving class. Init: Instance method of NSObject. Implemented by subclasses to initialize a new object (the receiver) immediately after memory for it has been allocated. New: Class method of NSObject. Allocates a new instance of the receiving class, sends it an init message, and … Read more
There is no standard way to find this information. However, some implementations provide functions like msize to do this. For example: _msize on Windows malloc_size on MacOS malloc_usable_size on systems with glibc Keep in mind though, that malloc will allocate a minimum of the size requested, so you should check if msize variant for your … Read more