concurrency

问题 I'm getting InvocationTargetException and NullPointerException when attempting to bind to custom class run by Task. I have working examples of binding to library classes ObeservableList, Long, Integer etc but now need to bind to values of custom class. I created TaskOutput class that includes StringProperty for binding purposes as follows: public class TaskOutput { private final StringProperty textValue = new SimpleStringProperty(); public TaskOutput(String textValue) { this.textValue.set

问题 Recently I had a need for a Dictionary that I could update from multiple threads, and the obvious candidate for this job was the build-in ConcurrentDictionary. Unfortunately I ended up not using it, and using instead a normal Dictionary protected with a lock , because of a fatal limitation: the TryRemove does not offer an overload that allows the conditional removal of an element. The available TryRemove method removes and returns the removed element, but in my case it was mandatory to remove

问题 race divides operations on an iterable automatically into threads. For instance, (Bool.roll xx 2000).race.sum would automatically divide the sum of the 2000-long array into 4 threads. However, benchmarks show that this is much slower than if race were not employed. This happens even if you make the array bigger. This happens even as the non-autothreaded version gets faster and faster with each version. (Auto-threading also gets faster, but is still twice as slow as not using it.) So the

问题 race divides operations on an iterable automatically into threads. For instance, (Bool.roll xx 2000).race.sum would automatically divide the sum of the 2000-long array into 4 threads. However, benchmarks show that this is much slower than if race were not employed. This happens even if you make the array bigger. This happens even as the non-autothreaded version gets faster and faster with each version. (Auto-threading also gets faster, but is still twice as slow as not using it.) So the

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 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 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 Given some code which does a bit of math/casting for each number from 1 to 500000, we have options: Simple for loop: for ^500000 -> $i { my $result = ($i ** 2).Str; } . In my unscientific benchmark, this takes 2.8 seconds. The most canonical parallel version does each bit of work in a Promise , then waits for the result. await do for ^500000 -> $i { start { my $result = ($i ** 2).Str; } } takes 19 seconds. This is slow! Creating a new promise must have too much overhead to be worthwhile for

问题 I've been playing around with Dart Isolates and have run into a problem using the isolate.pause(); function. import 'dart:io'; import 'dart:isolate'; main(){ ReceivePort receivePort = new ReceivePort(); Isolate.spawn(isolateEntryPoint, receivePort.sendPort).then((isolate){ isolate.pause(isolate.pauseCapability); }); } void isolateEntryPoint(SendPort sendPort){ while(true){ print("isolate is running"); sleep(new Duration(seconds: 2)); } } In my example the isolate basically just prints

问题 Right now I have some code that does roughly the following def generator(): while True: value = do_some_lengthy_IO() yield value def model(): for datapoint in generator(): do_some_lengthy_computation(datapoint) Right now, the I/O and the computation happen in serial. Ideally the should be running in parallel concurrently (the generator having ready the next value) since they share nothing but the value being passed. I started looking into this and got very confused with the multiprocessing ,