multithreading

问题 I know there is a system call pthread_equal in Linux for comparing 2 thread ids. But why cannot one directly compare 2 thread ids using '==' operator? 回答1: From the pthread_equal man page on Linux: The pthread_equal() function is necessary because thread IDs should be considered opaque: there is no portable way for applications to directly compare two pthread_t values. It might be a struct. It might be a pointer. It might be a pointer to a struct held somewhere. == might, or might not, return

问题 I know there is a system call pthread_equal in Linux for comparing 2 thread ids. But why cannot one directly compare 2 thread ids using '==' operator? 回答1: From the pthread_equal man page on Linux: The pthread_equal() function is necessary because thread IDs should be considered opaque: there is no portable way for applications to directly compare two pthread_t values. It might be a struct. It might be a pointer. It might be a pointer to a struct held somewhere. == might, or might not, return

问题 //... Some annoying getter ExecutorService es = Executors.newSingleThreadExecutor(); Future<Integer> result = es.submit(new Callable<Integer>() { public Integer call() throws Exception { //Get some value from the SQL database. } }); return result; Okay, I've looked all over. I need to know how I can make this wait until it finishes retrieving a value from a database to return this. 回答1: You use result.get() to wait for the task to finish and to retrieve the result. The API documentation is

问题 How does one read and split/chunk a file by the number of lines? I would like to partition a file into separate buffers, while ensuring that a line is not split up between two or more buffers. I plan on passing these buffers into their own pthreads so they can perform some type of simultaneous/asynchronous processing. I've read the answer below reading and writing in chunks on linux using c but I don't think it exactly answers the question about making sure that a line is not split up into

问题 I have 2 threads. I want to tell one of them to run on first cpu and the second one on the second cpu for example in a machine with two cpu. how can I do that? this is my code UCI UCIMain = new UCI(); Thread UCIThread = new Thread(new ThreadStart(UCIMain.main)); UCIThread.Priority = ThreadPriority.BelowNormal; UCIThread.Start(); and for sure the class UCI has a member function named main . I want to set this thread in 1st processor for example 回答1: I wouldn't recommend this, but if you really

问题 Consider the following piece of code: package com.sarvagya; import java.util.Arrays; import java.util.List; import java.util.concurrent.ExecutionException; import java.util.concurrent.ForkJoinPool; import java.util.stream.Collectors; public class Streamer { private static final int LOOP_COUNT = 2000; public static void main(String[] args){ try{ for(int i = 0; i < LOOP_COUNT; ++i){ poolRunner(); System.out.println("done loop " + i); try{ Thread.sleep(50L); } catch (Exception e){ System.out

问题 I am using FileSystemWatcher to monitor any changes in the app.config file. And also, writing to the config file. Here is my code : MyApplication is the main project and DataCache is a clas library referenced in MyApplication. using System; using System.Threading; using System.IO; namespace MyApplication { public class Program { public static string rootFolderPath = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location); public static string configFilePath = Path

问题 I am using FileSystemWatcher to monitor any changes in the app.config file. And also, writing to the config file. Here is my code : MyApplication is the main project and DataCache is a clas library referenced in MyApplication. using System; using System.Threading; using System.IO; namespace MyApplication { public class Program { public static string rootFolderPath = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location); public static string configFilePath = Path

问题 Here is a C++17 snippet where on thread waits for another to reach certain stage: std::condition_variable cv; std::atomic<bool> ready_flag{false}; std::mutex m; // thread 1 ... // start a thread, then wait for it to reach certain stage auto lock = std::unique_lock(m); cv.wait(lock, [&]{ return ready_flag.load(std::memory_order_acquire); }); // thread 2 ... // modify state, etc ready_flag.store(true, std::memory_order_release); std::lock_guard{m}; // NOTE: this is lock immediately followed by

问题 Previously, when I use single-producer mode of disruptor, e.g. new Disruptor<ValueEvent>(ValueEvent.EVENT_FACTORY, 2048, moranContext.getThreadPoolExecutor(), ProducerType.Single, new BlockingWaitStrategy()) the performance is good. Now I am in a situation that multiple threads would write to a single ring buffer. What I found is that ProducerType.Multi make the code several times slower than single producer mode. That poor performance is not going to be accepted by me. So should I use single