overhead

问题 I wrote a video play view, it is a SurfaceView with a MediaPlayer instance. I attached the mediaplayer to the surface holder when surface created then start the play. This is easy and everyone knows the details. But I want to draw a bitmap which is the first frame of the video to the surfaceview.Canvas is not a choice to draw the bitmap, because it will disable the mediaplayer to connect. Since api level 14, we can new a surface with surfacetexture. So we can use opengl es to draw video frame

问题 I know that pointers store the address of the value that they point to, but if you display the value of a pointer directly to the screen, you get a hexadecimal number. If the number is exactly what the pointer stores, then when saying pA = pB; //both are pointers you're copying the address. Then wouldn't there be a bigger overhead to using pointers when working with very small items like int s and bool s? 回答1: A pointer is essentially just a number. It stores the address in RAM where the data

问题 I have a HTTP handler that has 40 loggers that is set to os.Stdout . It works just fine for me as I am the only one testing at the moment. But, when it goes to the production, I'm afraid it will have too much overhead. Currently loggers are set to os.Stdout and os.Stderr . But once it gets to the production, os.Stdout will be set to ioutil.discard . Q1. Will it impact the performance if I still have the logger in set to discard? Q2. For the best practice, is it better to remove loggers

问题 Somewhere I read (rephrased): If we compare a UTF-8 encoded file VS a UTF-16 encoded file, At some times, the UTF-8 file may give a 50% to 100% larger file size Am I right to say that the article is wrong because at all times , text encoded in UTF-8 will never give us more than a +50% file size of the same text encoded in UTF-16? 回答1: The answer is that in UTF-8, ASCII is just 1 byte, but that in general, most Western languages including English use a few characters here and there that

问题 Are there are any performance cost by creating, throwing and catching exceptions in Java? I am planing to add 'exception driven development' into a larger project. I would like to design my own exceptions and include them into my methods, forcing developers to catch and do appropriate work. For example, if you have a method to get a user from the database based on a name. public User getUser(String name); However, it is possible that the user might be null and it is common to forget to check

问题 When measuring elapsed time on a low level, I have the choice of using any of these: System.currentTimeMillis(); System.nanoTime(); Both methods are implemented native . Before digging into any C code, does anyone know if there is any substantial overhead calling one or the other? I mean, if I don't really care about the extra precision, which one would be expected to be less CPU time consuming? N.B: I'm using the standard Java 1.6 JDK, but the question may be valid for any JRE... 回答1: The

问题 A lot of literature talks about using inline functions to "avoid the overhead of a function call". However I haven't seen quantifiable data. What is the actual overhead of a function call i.e. what sort of performance increase do we achieve by inlining functions? 回答1: On most architectures, the cost consists of saving all (or some, or none) of the registers to the stack, pushing the function arguments to the stack (or putting them in registers), incrementing the stack pointer and jumping to

问题 Is there any overhead in Java for using a try/catch block, as opposed to an if block (assuming that the enclosed code otherwise does not request so)? For example, take the following two simple implementations of a "safe trim" method for strings: public String tryTrim(String raw) { try { return raw.trim(); } catch (Exception e) { } return null; } public String ifTrim(String raw) { if (raw == null) { return null; } return raw.trim(); } If the raw input is only rarely null , is there any

问题 I know there's no single hard-and-fast answer, but is there a generic order-of-magnitude estimate approximation for the encryption overhead of SSL versus unencrypted socket communication? I'm talking only about the comm processing and wire time, not counting application-level processing. Update There is a question about HTTPS versus HTTP, but I'm interested in looking lower in the stack. (I replaced the phrase "order of magnitude" to avoid confusion; I was using it as informal jargon rather

问题 I ran the visual profiler on a CUDA application of mine. The application calls a single kernel multiple times if the data is too large. This kernel has no branching. The profiler reports a high instruction replay overhead of 83.6% and a high global memory instruction replay overhead of 83.5% . Here is how the kernel generally looks: // Decryption kernel __global__ void dev_decrypt(uint8_t *in_blk, uint8_t *out_blk){ __shared__ volatile word sdata[256]; register uint32_t data; // Thread ID