multithreading

问题 ExecutorService executorService = Executors.newSingleThreadExecutor(); Set<Callable<String>> callables = new HashSet<Callable<String>>(); callables.add(new Callable<String>() { public String call() throws Exception { return "Task 1"; } }); callables.add(new Callable<String>() { public String call() throws Exception { return "Task 2"; } }); callables.add(new Callable<String>() { public String call() throws Exception { return "Task 3"; } }); List<Future<String>> futures = executorService

问题 sleep() is a static method of class Thread. How does it work when called from multiple threads. and how does it figure out the current thread of execution. ? or may be a more generic Question would be How are static methods called from different threads ? Won't there be any concurrency problems ? 回答1: how does it figure out the current thread of execution? It doesn't have to. It just calls the operating system, which always sleeps the thread that called it. 回答2: The sleep method sleeps the

问题 sleep() is a static method of class Thread. How does it work when called from multiple threads. and how does it figure out the current thread of execution. ? or may be a more generic Question would be How are static methods called from different threads ? Won't there be any concurrency problems ? 回答1: how does it figure out the current thread of execution? It doesn't have to. It just calls the operating system, which always sleeps the thread that called it. 回答2: The sleep method sleeps the

问题 I have a process where multiple threads open multiple socket connection. I want to view this information and map what thread has opened which socket port. lsof -i and netstat command gives the process ID, but couldn't display thread id. Is there any command which prints this information? 回答1: As MarkR suggested, you need to use strace from startup: strace -fp <pid> The above command will show you per thread system calls like open(), read(), recv() etc, along with the descriptors used: [pid

问题 I run C++ program in Linux. There are several threads pool (for computation, for io, for ... such things). The system call clock() gives me a way to measure the CPU time spent by all the CPU cores for the process. However, I want to measure the CPU time spent only by the threads in the computation threads pool. How can I achieve it? Thanks :D 回答1: To get CPU clock ID of every thread you can use: pthread_getcpuclockid and using this CPU clock ID you can retrieve the current thread CPU time

问题 I have server ServerSocket socketListener = new ServerSocket(Config.PORT); ... client = socketListener.accept(); and client sock = new Socket("127.0.0.1", Config.PORT); I want to transfer between them some serialized data using ObjectInputStream and ObjectOutputStream. When I try to do ObjectInputStream inputStream = new ObjectInputStream(socket.getInputStream()); Nothing happens neither on the server side nor client side. Everything falls on that line. Both the client and the server is

问题 I have server ServerSocket socketListener = new ServerSocket(Config.PORT); ... client = socketListener.accept(); and client sock = new Socket("127.0.0.1", Config.PORT); I want to transfer between them some serialized data using ObjectInputStream and ObjectOutputStream. When I try to do ObjectInputStream inputStream = new ObjectInputStream(socket.getInputStream()); Nothing happens neither on the server side nor client side. Everything falls on that line. Both the client and the server is

问题 I built a simple chat application using nio channels. I am very much new to networking as well as threads. This application is for communicating with server (Server / Client chat application). My problem is that multiple clients are not supported by the server. How do I solve this problem? What's the bug in my code? public class Clientcore extends Thread { SelectionKey selkey=null; Selector sckt_manager=null; public void coreClient() { System.out.println("please enter the text");

问题 I have code that looks something like this: [SVProgressHUD show]; [imageGenerator generateCGImagesAsynchronouslyForTimes:times completionHandler:^(CMTime requestedTime, ...) { dispatch_group_async(queueGroup, queue, ^{ // Do stuff }); }]; dispatch_group_wait(queueGroup, DISPATCH_TIME_FOREVER); [SVProgressHUD dismiss]; Basically, display a loading animation HUD and start generating image thumbnails from an asset, then once it's done hide the HUD. I'm using a dispatch group since i want to make

问题 This question already has answers here : Difference between shutdown and shutdownNow of Executor Service (3 answers) Closed 2 years ago . I am executing a java code where I have an AtomicInteger on which 1000 threads are trying to perform an incrementAndGet() . I was expecting the final value to be 1000. But each run is generating all sorts of different values. The code is as follows : class task implements Runnable { AtomicInteger i ; task(AtomicInteger ai) {i =ai ;} public void run() { i