multithreading

问题 I am trying to learn about the ForkJoinPool framework and came across the below example: public class ArrayCounter extends RecursiveTask<Integer> { int[] array; int threshold = 100_000; int start; int end; public ArrayCounter(int[] array, int start, int end) { this.array = array; this.start = start; this.end = end; } protected Integer compute() { if (end - start < threshold) { return computeDirectly(); } else { int middle = (end + start) / 2; ArrayCounter subTask1 = new ArrayCounter(array,

问题 I was going through one of the tutorials on memory model of Java and came across this concept of field visibility which happens in multi-threaded programming. I tried to simulate the same using the below code, however , I see in each thread, the latest value is being reflected (in ReaderThread). The below is the complete program. Edit After some suggestion to use while(somevariable), I incorporated, but still getting the same behaviour. I removed sysout on reading the x FieldVisibility.java

问题 I was going through one of the tutorials on memory model of Java and came across this concept of field visibility which happens in multi-threaded programming. I tried to simulate the same using the below code, however , I see in each thread, the latest value is being reflected (in ReaderThread). The below is the complete program. Edit After some suggestion to use while(somevariable), I incorporated, but still getting the same behaviour. I removed sysout on reading the x FieldVisibility.java

问题 I was going through one of the tutorials on memory model of Java and came across this concept of field visibility which happens in multi-threaded programming. I tried to simulate the same using the below code, however , I see in each thread, the latest value is being reflected (in ReaderThread). The below is the complete program. Edit After some suggestion to use while(somevariable), I incorporated, but still getting the same behaviour. I removed sysout on reading the x FieldVisibility.java

问题 Now I am in one of the threads of process A , I need to create new process B in current thread, and run in process B function MyFunc() . How can I do it ? I found how to create a child process from current process: click . But how can I run MyFunc() in this new process ? This 2 processes should run async, and not wait each other like in this example: // Wait until child process exits. WaitForSingleObject( pi.hProcess, INFINITE ); ETA: I work on windows 回答1: I assume you are running under

问题 This question already has answers here : Java ServiceExecutor terminating condition (4 answers) Closed 5 years ago . I don't understand why I have to call executorService.shutdown() explicitly to terminate executorService. If I will not call shutdown() then the JVM will not terminate on its own. What is wrong with my program or what concept I am lacking? public class ExecutorServiceExample { public static class Task1 implements Runnable { @Override public void run() { try { Thread.sleep(1000)

问题 I'm getting what I think are false positives when using helgrind with C++11 futures and packaged tasks. The following is with gcc-6.3.0 and valgrind-3.12 on a CentOS6 system. I've tried to follow the advice in the documentation to provide annotations. Have I done something wrong? What should I do to avoid the false positives, or is there really a race? drdws0134$ cat hthread.cpp #include <valgrind/helgrind.h> #define _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(addr) ANNOTATE_HAPPENS_BEFORE(addr)

问题 I've seen on various mailing lists and forums that people keep mentioning that the print function in Python 3 is thread safe. From my own testing, I see no reason to doubt that. import threading import time import random def worker(letter): print(letter * 50) threads = [threading.Thread(target=worker, args=(let,)) for let in "ABCDEFGHIJ"] for t in threads: t.start() for t in threads: t.join() When I run it with Python 3, even though some of the lines may be out of order, they are still always

问题 I have got the following code: public void Update(Foo foo) { lock(_locker) { UpdateFirstPart(foo.First); UpdateSecondPart(foo.Second); UpdateThirdPart(foo.Third); } } public class Foo { public int Id; public Some1 First; public Some2 Second; public Some3 Third; } Method Update can be performed in two or more threads and I use lock to prevent cuncurency problems with foo . But I would like to lock only those Foo that have similar Id . For instance if one thread executes method Update with Foo

问题 The goal is to achieve full usage of the available cores, in converting floats to strings in a single Delphi application. I think this problem applies to the general processing of string. Yet in my example I am specifically using the FloatToStr method. What I am doing (I've kept this very simple so there is little ambiguity around the implementation): Using Delphi XE6 Create thread objects which inherit from TThread, and start them. In the thread execute procedure it will convert a large