executorservice

问题 In a typical JAVA application, one configures a global ExecutorService for managing a global thread pool. Lets say I configure a fixed thread pool of 100 threads: ExecutorService threadPool = Executors.newFixedThreadPool(100); Now lets say that I have a list of 1000 files to upload to a server, and for each upload I create a callable that will handle the upload of this one file. List<Callable> uploadTasks = new ArrayList<Callable>(); // Fill the list with 1000 upload tasks How can I limit the

问题 I have a multithreaded implementation where i create an ExecutorService and submit tasks to be executed, i want to know when all the threads is submited have finished without blocking the main thread and the UI. I've tried ExecutorService.awaitTermination() but it blocks the main thread and the UI. I've searched alot but i can't seem to find an elegant way of doing this. I'm currently thinking about creating another thread that counts the amount of threads finished and launches an event when

问题 I'm slightly confused by the internal scheduling mechanism of the ExecutorService and the ForkJoinPool. I understood the ExecutorService scheduling is done this way. A bunch of tasks are queued. Once a thread is available it will handle the first available task and so forth. Meanwhile, a ForkJoinPool is presented as distinct because it uses a work-stealing algorithm. If I understand correctly it means a thread can steal some tasks from another thread. Yet, I don't really understand the

问题 Lets assume I'm planning to use one executorservice in my entire application, to which I'm sending new runnable's or callable's to execute/submit, and I ommit to shutdown right after I do that. I just want to throw my "tasks" to the executorservice and let him handle them and execute them giving it's resources (how many threads he has available, and how many he can create if needed and then queue those tasks accordingly). From your experience of using ExecutorService in Android application,

问题 I am pretty new to multithreading, and I am working on a project where I am trying to utilize 4 CPUs in my Java program. I wanted to do something like int numProcessors = Runtime.getRuntime().availableProcessors(); ExecutorService e = Executors.newFixedThreadPool(numProcessors); Will this guarantee that I will have one thread working per CPU? At the time that I create the threads, the system will not be busy, however some time afterwards it will be extremely busy. I thought that the OS will

问题 The Problem I'm running multiple invocations of some external method via an ExecutorService. I would like to be able to interrupt these methods, but unfortunately they do not check the interrupt flag by themselves. Is there any way I can force an exception to be raised from these methods? I am aware that throwing an exception from an arbitrary location is potentially dangerous, in my specific case I am willing to take this chance and prepared to deal with the consequences. Details By

问题 I have the below program which send the mail using java mail api , now this the is the simple program i have developed now i want to modify in terms of parallel execution by using executorframework that i want that 5 different threads independently should trigger my this program but those 5 different threads should trigger simultaneously at the same time lets say there are five different threads t1,t2,t3,t4 and t5 then all of them should independently hit my function which is main(@) is

问题 Are there any java.util.ExecutorService implementations which simply run all executed tasks in the calling thread? If this isn't included in Java by default, is there a library which contains an implementation like this? 回答1: The only existing implementation I could find is SynchronousExecutorService - unfortunately buried somewhere in camel library. Pasting source code (without comments) here for future reference: package org.apache.camel.util.concurrent; import java.util.List; import java

问题 When using the ExecutorService returned by Executors.newSingleThreadExecutor() , how do I interrupt it? 回答1: In order to do this, you need to submit() a task to an ExecutorService , rather than calling execute() . When you do this, a Future is returned that can be used to manipulate the scheduled task. In particular, you can call cancel(true) on the associated Future to interrupt a task that is currently executing (or skip execution altogether if the task hasn't started running yet). By the

问题 import java.util.Arrays; import java.util.Iterator; import java.util.List; import java.util.concurrent.Callable; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Future; import java.util.concurrent.TimeUnit; class Task implements Callable<String> { public String call() throws Exception { String s = "initial"; try { System.out.println("Started.."); /*for (int i=0;i<10000;i++) { if (i % 2 == 0) { System.out.println("Even"); } }*/