synchronization

问题 I have the following class which contains only one field i . Access to this field is guarded by the lock of the object ("this"). When implementing equals() I need to lock this instance (a) and the other (b). If thread 1 calls a.equals(b) and at the same time thread 2 calls b.equals(a), the locking order is reverse in the two implementations and may result in deadlock. How should I implement equals() for a class which has synchronized fields? public class Sync { // @GuardedBy("this") private

问题 Is there a function in pthread library to synchronize threads? Not mutexes, not semaphores, just one call function. It is supposed to lock the threads that get in that point until all the threads reach such function. E.g: function thread_worker(){ //hard working syncThreads(); printf("all threads are sync\n"); } So the printf is called only when all the threads end the hard working. 回答1: The proper way to do this would be with a barrier . pthread supports barriers using pthread_barrier_t .

问题 We have a normalized SQL Server 2008 database designed using generic tables. So, instead of having a separate table for each entity (e.g. Products, Orders, OrderItems, etc), we have generic tables (Entities, Instances, Relationships, Attributes, etc). We have decided to have a separate denormalized database for quick retrieval of data. Could you please advise me of various technologies out there to synchronize these 2 databases, assuming they have different schemas? Cheers, Mosh 回答1: When two

问题 Consider a scenario where a browser has two or more tabs pointing to the same origin. Different event loops of the different tabs can lead to race conditions while accessing local storage and the different tabs can potentially overwrite each other's changes in local storage. I'm writing a web application that would face such race conditions, and so I wanted to know about the different synchronization primitives that could be employed in such a scenario. 回答1: My reading of the relevant W3C

问题 I have started a thread on this at DirectShow.NET's forum, here is the link http://sourceforge.net/projects/directshownet/forums/forum/460697/topic/5194414/index/page/1 but unfortunately the problem still persists... I have an application that captures video from a webcam and audio from the microphone and save it to a file, for some reason the audio and video are never in-sync, i tried the following: 1. Started with ffdshow encoder and changed to AVI Mux - problem persists, audio is delayed

问题 My code: #include <iostream> #include <thread> void function_1() { std::cout << "Thread t1 started!\n"; for (int j=0; j>-100; j--) { std::cout << "t1 says: " << j << "\n"; } } int main() { std::thread t1(function_1); // t1 starts running for (int i=0; i<100; i++) { std::cout << "from main: " << i << "\n"; } t1.join(); // main thread waits for t1 to finish return 0; } I create a thread that prints numbers in decreasing order while main prints in increasing order. Sample output here. Why is my

问题 If we have a method: public void doSomething(){ synchronized(this){ //some code processing here } String temp = "init"; //instead of i++ synchronized(this){ //some other code processing here } } Is this method equivalent to public synchronized void doSomething() ? Is there any reason not to assume that the thread scheduler in some executions would not result in effectively the same flow as synchronizing the whole function? That is: Thread1 enters the first synchronized block. Thread2 blocks.

问题 Are machine word size (or smaller) writes serialized? Only one native opcode is needed to copy register content to RAM. 回答1: Writing data to RAM is atomic. If two CPUs try to write to the same location at the same time, the memory controller will decide on some order for the writes. While one CPU is writing to memory, the other CPU will stall for as many cycles as necessary until the first write is completed; then it will overwrite its value. This is what's known as a race condition. Writes

问题 I am currently working for a Scrum Team that is using a shared git repository with another Scrum Team. For ease, we will call my scrum team Autobot and the other Decepticon . Team Decepticon has full push and pull access to the repository, and are in charge of the framework. Team Autobot is able to pull, but not to push. Generally there is no issue if members of the team work independently. However, cases arise where it would be useful to pull and push to another team members branch. As of

问题 I just found the following OpenGL specification for ARB_map_buffer_range. I'm wondering if it is possible to do non-blocking map calls using this extension? Currently in my application im rendering to an FBO which I then map to a host PBO buffer. glMapBuffer(target_, GL_READ_ONLY); However, the problem with this is that it blocks the rendering thread while transferring the data. I could reduce this issue by pipelining the rendering, but latency is a big issue in my application. My question is