在一個播放框架項目控制器中，我正在使用 forEach() 處理一個對象列表，它工作正常。List<Post> posts = repository.getPosts();posts.forEach(post -> { //...some processing anyFunc(); //<-- internally uses HttpExecutionContext //...further processing});但是當我嘗試使用 parallelStream() 并行處理這些對象列表以提高性能時，我在并行流中丟失了 HttpExecutionContext 實例。List<Post> posts = repository.getPosts();posts.parallelStream().forEach(post -> { //...some processing anyFunc(); //<-- not able to use HttpExecutionContext now //...further processing});我無法將 HttpExecutionContext 作為參數傳遞給anyFunc. 有什么方法可以在 parallelStream() 中傳遞/設置 HttpExecutionContext 嗎？
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TA貢獻1883條經驗 獲得超3個贊
使用HttpExecutionContext.execute
public class HomeController extends Controller {
@Inject HttpExecutionContext ec;
public Result index() {
// The data to parallel processing
List<String> list = List.of("Item 1", "Item 2", "Item 3","Item 4", "Item 5", "Item 6", "Item 7", "Item 8");
// Make a Stream. The `parallelStream` is not used because
// `current.execute` will make it run in parallel.
Stream<String> listInParralel = list.stream();
// The current executor with the HTTP context.
Executor current = ec.current();
System.out.println("START");
listInParralel.forEach(item -> {
current.execute(()-> {
// request().uri() internally uses HttpExecutionContext
System.out.println("item: " + item + " in " + request().uri() + "(" + Thread.currentThread().getName() + ")");
});
});
// Results
/*
START
item: Item 7 in /(application-akka.actor.default-dispatcher-9)
item: Item 5 in /(application-akka.actor.default-dispatcher-7)
item: Item 3 in /(application-akka.actor.default-dispatcher-5)
item: Item 1 in /(application-akka.actor.default-dispatcher-6)
item: Item 6 in /(application-akka.actor.default-dispatcher-8)
item: Item 4 in /(application-akka.actor.default-dispatcher-2)
item: Item 2 in /(application-akka.actor.default-dispatcher-4)
item: Item 8 in /(application-akka.actor.default-dispatcher-9)
*/
return ok("Done");
}
}
不過，我更喜歡緩存 HTTP 數據，然后在并行處理中使用它們。不喜歡打擾HttpExecutionContext：
public class HomeController extends Controller {
@Inject HttpExecutionContext ec;
public Result index() {
// The data to parallel processing
List<String> list = List.of("Item 1", "Item 2", "Item 3","Item 4", "Item 5", "Item 6", "Item 7", "Item 8");
Stream<String> listInParralel = list.parallelStream();
// Take all that you need from the HttpExecutionContext.
String uri = request().uri();
System.out.println("START");
listInParralel.forEach(item -> {
// use pre cached HTTP context data, liek `uri`
System.out.println("item: " + item + " in " + uri + "(" + Thread.currentThread().getName() + ")");
});
// Results
/*
START
item: Item 1 in /(ForkJoinPool.commonPool-worker-7)
item: Item 8 in /(ForkJoinPool.commonPool-worker-3)
item: Item 7 in /(ForkJoinPool.commonPool-worker-15)
item: Item 4 in /(ForkJoinPool.commonPool-worker-9)
item: Item 3 in /(ForkJoinPool.commonPool-worker-13)
item: Item 2 in /(ForkJoinPool.commonPool-worker-5)
item: Item 5 in /(ForkJoinPool.commonPool-worker-11)
item: Item 6 in /(application-akka.actor.default-dispatcher-4)
*/
return ok("Done");
}
}
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