问题描述
我想在+ -42Mio记录的数据库上运行许多任务。我想分批运行5000个记录/次（结果850个任务）。
我还想限制线程数（到16）java开始为我做这个并且我使用当前代码来完成这个任务：
I want to launch a lot of tasks to run on a database of +-42Mio records. I want to run this in batches of 5000 records/time (results in 850 tasks).I also want to limit the number of threads (to 16) java starts to do this for me and I am using the current code to accomplish this task:
ExecutorService executorService = Executors.newFixedThreadPool(16);
for (int j = 1; j < 900 + 1; j++) {
int start = (j - 1) * 5000;
int stop = (j) * 5000- 1;
FetcherRunner runner = new FetcherRunner(routes, start, stop);
executorService.submit(runner);
Thread t = new Thread(runner);
threadsList.add(t);
t.start();
}
这是正确的方法吗？特别是因为我的印象是java只会触发所有任务......（ FetcherRunner 实现 runnable ）
Is this the correct way to do this? Particularly as I have the impression that java just fires away all tasks ...(FetcherRunner implements runnable)
推荐答案
使用ExecutorService的第一部分看起来不错：
The first part using ExecutorService looks good:
...
FetcherRunner runner = new FetcherRunner(routes, start, stop);
executorService.submit(runner);
有线程的部分不应该在那里，我假设你在那里只是为了向你展示之前有吗？
The part with Thread should not be there, I am assuming you have it there just to show how you had it before?
更新：
是的，您不需要 executorService之后的代码。提交（跑步者），这最终会产生大量的线程。如果您的目标是在循环之后等待所有提交的任务完成，那么您在提交任务时可以获得对 Future 的引用并等待未来，如下所示：
Update:Yes, you don't require the code after executorService.submit(runner), that is going to end up spawning a huge number of threads. If your objective is to wait for all submitted tasks to complete after the loop, then you can get a reference to Future when submitting tasks and wait on the Future, something like this:
ExecutorService executorService = Executors.newFixedThreadPool(16);
List<Future<Result>> futures = ..;
for (int j = 1; j < 900+ 1; j++) {
int start = (j - 1) * 5000;
int stop = (j) * 5000- 1;
FetcherRunner runner = new FetcherRunner(routes, start, stop);
futures.add(executorService.submit(runner));
}
for (Future<Result> future:futures){
future.get(); //Do something with the results..
}
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